Synthesis and biological activity of a novel class of small molecular weight peptidomimetic competitive inhibitors of protein tyrosine phosphatase 1B

Article abstract of DOI:10.1021/jm010393s

Protein tyrosine phosphatase 1B (PTP1B) negatively regulates insulin signaling in part by dephosphorylating key tyrosine residues within the regulatory domain of the β-subunit of the insulin receptor (IR), thereby attenuating receptor tyrosine kinase acti

Full text of DOI:10.1021/jm010393s

598
J . Med. Chem. 2002, 45, 598-622
Syn th esis a n d Biologica l Activity of a Novel Cla ss of Sm a ll Molecu la r Weigh t
P ep tid om im etic Com p etitive In h ibitor s of P r otein Tyr osin e P h osp h a ta se 1B
Scott D. Larsen,*,† Tjeerd Barf,‡ Charlotta Liljebris‡, Paul D. May†, Derek Ogg,§ Theresa J . O’Sullivan,†
Barbara J . Palazuk,| Heinrich J . Schostarez†, F. Craig Stevens†, and J ohn E. Bleasdale|
Departments of Medicinal Chemistry and Cell & Molecular Biology, Pharmacia Corporation, Kalamazoo, Michigan 49007;
Department of Medicinal Chemistry, Biovitrum AB, SE-75182 Uppsala, Sweden; and Department of Structural Chemistry,
Biovitrum AB, SE-112 87 Stockholm, Sweden
Received August 17, 2001
Protein tyrosine phosphatase 1B (PTP1B) negatively regulates insulin signaling in part by
dephosphorylating key tyrosine residues within the regulatory domain of the â-subunit of the
insulin receptor (IR), thereby attenuating receptor tyrosine kinase activity. Inhibition of PTP1B
is therefore anticipated to improve insulin resistance and has recently become the focus of
discovery efforts aimed at identifying new drugs to treat type II diabetes. We previously reported
that the tripeptide Ac-Asp-Tyr(SO3H)-Nle-NH2 is a surprisingly effective inhibitor of PTP1B
(Ki ) 5 µM). With the goal of improving the stability and potency of this lead, as well as
attenuating its peptidic character, an analogue program was undertaken. Specific elements of
the initial phase of this program included replacement of the N- and C-termini with non-amino
acid components, modification of the tyrosine subunit, and replacement of the tyrosine sulfate
with other potential phosphate mimics. The most potent analogue arising from this effort was
triacid 71, which inhibits PTP1B competitively with a Ki ) 0.22 µM without inhibiting SHP-2
or LAR at concentrations up to 100 µM. Overall, the inhibitors generated in this work showed
little or no enhancement of insulin signaling in cellular assays. However, potential prodrug
triester 70 did induce enhancements in 2-deoxyglucose uptake into two different cell lines with
concomitant augmentation of the tyrosine phosphorylation levels of insulin-signaling molecules.
Key elements of the overall SAR reported herein include confirmation of the effectiveness and
remarkable PTP1B-specificity of the novel tyrosine phosphate bioisostere, O-carboxymethyl
salicylic acid; demonstration that the tyrosine skeleton is optimal relative to closely related
structures; replacement of the p-1 aspartic acid with phenylalanine with little effect on activity;
and demonstration that inhibitory activity can be maintained in the absence of an N-terminal
carboxylic acid. An X-ray cocrystal structure of an analogue bearing a neutral N-terminus (69)
bound to PTP1B is reported that confirms a mode of binding similar to that of peptidic
substrates.
In tr od u ction
receptor substrate-1 (IRS-1). Following multiple tyrosyl
phosphorylations, IRS-1 propagates the insulin signal
by docking with and subsequently activating a number
of effector proteins. The insulin signal branches at this
point, eventually leading to the multiple observed
responses to insulin that occur within minutes (e.g.,
glucose uptake) or many hours (e.g., mitogenesis).2b The
underlying defect in type II diabetes is an attenuation
of this insulin-signaling cascade, apparently originating
at or near the level of the IR itself.3
An important component of the current therapy for
type II diabetes has been the administration of agents
that augment secretion of insulin from the pancreas.
While this effectively reduces circulating plasma glucose
levels in some patients, it does not address the underly-
ing factor responsible for the hyperglycemia, namely the
insulin resistance of the peripheral tissues.1 Under
normal physiological conditions, insulin exerts its effects
via initially binding to the extracellular domain (R-
subunit) of the insulin receptor (IR), thereby effecting
a conformational change in the intracellular domain (â-
subunit) of the IR. This in turn activates an intrinsic
tyrosine kinase present on the â-subunit, resulting in
the phosphorylation of key tyrosine residues within the
â-subunit (autophosphorylation).2a In this phosphoryl-
ated state, the IR possesses high tyrosine kinase activity
toward proximal signaling molecules such as insulin
One strategy to combat this insulin resistance thera-
peutically may be to maintain insulin receptors (IR) in
the active tyrosine-phosphorylated form by inhibiting
enzymes that catalyze IR dephosphorylation. There is
evidence that protein tyrosine phosphatase 1B (PTP1B)
catalyzes IR dephosphorylation and is involved physi-
ologically and pathologically in terminating insulin
signaling. This evidence includes descriptions of both
in vitro4,5 and in vivo6 interactions between PTP1B and
IR. Purified PTP1B dephosphorylates IR, apparently in
the sequence observed in vivo, and dephosphorylation
results in loss of IR tyrosine kinase activity.7 Intracel-
lular delivery of neutralizing antibodies against PTP1B
was found to augment IR and IRS-1 phosphorylation,8
* To whom correspondence should be addressed. Tel: 616-833-7713.
Fax: 616-833-2516. E-mail: scott.d.larsen@pharmacia.com.
† Department of Medicinal Chemistry, Pharmacia Corp.
‡ Department of Medicinal Chemistry, Biovitrum AB.
§ Department of Structural Chemistry, Biovitrum AB.
|| Department of Cell and Molecular Biology, Pharmacia Corp.
10.1021/jm010393s CCC: $22.00 © 2002 American Chemical Society
Published on Web 12/29/2001

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 599
Sch em e 1
while conversely, overexpression of PTP1B in trans-
fected cells inhibited IR and IRS-1 phosphorylation.9
Furthermore, PTP1B activity is increased in some
tissues of obese insulin-resistant patients10 and is
reduced in parallel with the increased insulin sensitivity
that accompanies weight loss.10,11 Experimentally in-
duced insulin resistance in a variety of cell models is
accompanied by an increase in PTP1B activity.12,13 In
addition, correction of glucose-induced insulin resistance
in Rat1 fibroblasts with a thiazolidinedione insulin
sensitizer also corrects the elevation of PTP1B activity
in the insulin-resistant cells.13 Recently, it was reported
that PTP1B null mice have increased insulin sensitivity
and decreased susceptibility to diet-induced obesity, but
otherwise appear normal.14
Reagents: (a) n-C5H11NH2, EDC; (b) HCl/dioxane; (c) succinic
anhydride, TEA, CH2Cl2; (d) SO3-pyridine, DMF.
Sch em e 2
Inhibition of PTP1B may thus be an effective means
by which to treat type II diabetes, and research in this
field has accelerated dramatically in recent years.
Because the catalytic activity of PTP1B relies on the
viability of an active site cysteine thiol (Cys215), inhibi-
tion of the enzyme can be readily achieved by simple
complexation with metals, chemical oxidation, or cap-
ture with electrophiles.15 It is unlikely, however, that
any of these approaches will provide inhibitors with
specificity for PTP1B over the many other PTP enzymes
present in cells, a requirement that would be expected
for a safe drug with minimal side effects. An alternative
approach, which is more likely to be selective, is to
develop reversible competitive inhibitors that mimic the
natural substrate, a phosphotyrosine-containing polypep-
tide. Because tyrosine phosphates are chemically labile,
intensive research has been undertaken to develop
chemically and enzymatically stable mimics that main-
tain high affinity for the enzyme active site.16,17 Ex-
amples of functional groups successfully employed as
phosphate mimics in PTP1B inhibitors include meth-
ylenephosphonate, difluoromethylenephosphonate, sul-
fate, malonate, and carboxylate.17
At the outset of the present work, it was generally
accepted that a minimum of six amino acid residues was
required for peptidic substrates or inhibitors to possess
high affinity for PTP1B.18 We were, therefore, surprised
to discover that the simple tripeptide Ac-NH-Asp-Tyr-
(SO3H)-Nle-NH2 (1) is a highly effective inhibitor of
PTP1B (Ki ) 5 µM).19 A similar result was recently
obtained by Ramachandran et al., who reported that the
simple sulfotyrosyl-containing tetrapeptide AcDE(sY)-
Nle inhibits PTP1B with an IC50 of 2 µM.20 Because of
the relatively low molecular weight of our tripeptide
inhibitor, we were encouraged to embark on an analogue
program aimed at developing peptidomimetic inhibitors
based on this peptide lead, an endeavor that ultimately
led to the identification of submicromolar inhibitors of
relatively low molecular weight (<600 Da) and the
achievement of insulin-sensitizing effects in cells.19 In
this report, we provide details of the design, synthesis,
and structure-activity relationships of this novel class
of PTP1B inhibitors.
Reagents: (a) (i) HCl/dioxane, (ii) benzyl succinate, EDC, TEA;
(b) di-tert-butyl diazomalonate, Rh2(OAc)4, benzene; (c) TFA,
CH2Cl2; (d) H2, Pd/C, MeOH.
anhydride afforded succinamide 4. Sulfation of the
phenolic oxygen with sulfur trioxide-pyridine then
generated sulfotyrosine analogue 5.
Preparation of an O-malonate analogue of 5 is de-
scribed in Scheme 2. Deprotection of 3 and acylation
with monobenzyl succinate provided benzyl ester 6.
Rhodium-catalyzed alkylation of the phenol with di-tert-
butyl diazomalonate21 afforded triester 7, which was
sequentially deprotected with TFA and catalytic hydro-
genation to provide the desired triacid 8. Basic hydroly-
sis of the esters was avoided at this point to minimize
the chances of racemization at the chiral center.
The route in Scheme 2 had to be modified to allow
facile generation of analogues with varying substituents
at the N- and C-termini. Two different routes to N-
terminal analogues are depicted in Scheme 3. Alkylation
of protected tyrosines 3 and 10 with 2-halomalonate
esters afforded the O-malonates 11. We consistently
observed the generation of small amounts of haloge-
nated byproducts in these alkylations (e.g., 15) that
could not be easily removed chromatographically.22
Fortunately, subsequent catalytic hydrogenations ef-
fectively converted these side products into the desired
products, presumably via facile reduction of the halo-
gens. Urethanes 11 were deprotected with either HCl
or catalytic hydrogenation to afford amines 12. Acyla-
tion of the free amines could be effected either directly
Ch em istr y
A simplified version of tripeptide 1 lacking the
terminal amides was prepared as in Scheme 1. Amida-
tion of N-Boc-L-tyrosine 2 with n-pentylamine followed
by amine deprotection and acylation with succinic

600 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
Sch em e 3
Sch em e 5
Reagents: (a) n-C5H11NH2, EDC; (b) dibenzyl bromomalonate
or diethyl chloromalonate, K2CO3, acetone; (c) HCl/HOAc or H2,
Pd/C; (d) R3CO2H, EDC or (R3CO)2O, TEA; (e) H2, Pd/C or LiOH,
THF/MeOH.
Reagents: (a) Boc-Asp(OBn)OSu, TEA; (b) (i) HCl/HOAc, ii.
succinic anhydride, TEA; (c) H2, Pd/C.
Sch em e 6
Sch em e 4
Reagents: (a) (i) HCl/HOAc, (ii) n-C5H11COCl, (iii) H2, Pd/C.
a modified or substituted tyrosine core. Thus, starting
with racemic N-Boc-homotyrosine, o-fluorotyrosine, and
pentafluorotyrosine, analogues 19, 20, and 21 (Table 1)
were obtained, respectively.
Scheme 4 similarly outlines two alternate routes to
analogues modified at the C-terminus. Tyrosine ester
25 was acylated with monosuccinate esters as previ-
ously described. Alkylation with halomalonate esters
proceeded as before to provide the desired malonate
ethers 27 in good yields. Selective deprotection of the
C-terminal ester was effected with either TFA or via
catalytic hydrogenation, and the free acid could be
converted to various amides 29 with EDC and the
appropriate amine. Final deprotection via hydrogena-
tion or saponification afforded the desired triacids 30,
specific examples of which are compiled in Table 2.
Insertion of an aspartic acid residue is outlined in
Scheme 5. Coupling of amine 12a with N-Boc-aspartic
acid benzyl ester provided bis(amide) 31, which could
be directly deprotected to triacid 32 via hydrogenation.
Alternatively, the Boc group could be removed and the
reslulting free amine could be acylated with succinic
anhydride to afford mono acid 33. Hydrogenolytic
removal of the benzyl esters then afforded tetraacid 34.
The N-terminal amine could be capped with other acyl
groups, as exemplified in Scheme 6.
Reagents: (a) benzyl or methyl succinate, EDC, CH2Cl2; (b)
dienzyl bromomalonate or diethyl chloromalonate, K2CO3, acetone;
(c) TFA/CH2Cl2 or H2, Pd/C; (d) R4NH2, EDC, CH2Cl2; (e) H2, Pd/C
or LiOH, THF/MeOH.
with various anhydrides or with carboxylic acids under
the influence of EDC to give amides 13. Final removal
of the malonate esters was then accomplished either by
catalytic hydrogenation or saponification with LiOH,
affording malonic acids 14 (specific analogues are
compiled in Table 2). The latter conditions have been
frequently reported to successfully effect ester hydroly-
ses without racemization of amino acid chiral centers.
We confirmed this in our own work with later diaster-
eomeric analogues (vide infra). Synthetic routes analo-
gous to that depicted for the conversion of 2 to 14 in
Scheme 3 were used to prepare analogues incorporating
A route analogous to Scheme 5 was employed to insert
phenylalanine-derived amino acids, although here the
malonate was protected as the corresponding diethyl
ester (exemplified in Scheme 7). After amide coupling

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 601
Ta ble 1. Modifications of the Tyrosine Nucleus and Phosphate Bioisosteres
% inhibition of phosphatasesa(K i)
PTP1 PTP1B
cmpd
R1
R2
R3
n
LAR
SHP-2
5
8
OSO2OH
H
H
H
F
H
H
H
H
Fd
H
H
H
H
H
H
H
H
H
H
H
H
H
H
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
80 (30 µM)
51
5
2
0
4
12
6
8
10
9
23
0
0
OCH(CO2H)2
OCH(CO2H)2
OCH(CO2H)2
OCH(CO2H)2
OCOCH2CO2H
OCH2CO2H
76 (12 µM)
80 (11 µM)
19b
20b
21c
40
18
78
85
2
14
0
50
34
F
H
H
H
H
H
H
H
41
42
45
46
50
51
57
59
63
67
72 (R)
73
74
0
OSO2CH3
OC(CO2H)dC HCO2H
OCH(CO2H)CH2CO2H
CHdC(CO2H)2
CH2CH(CO2H)2
OCH2CO2H
5
4
52
3
5
3
2
1
4
0
33
34
2
3
0
0
0
0
1
CO2H
CO2H
CO2H
CONH2
H
93 (2.8 µM)
0
16
11
39
1
87 (6.5 µM)
OH
OCH2CONH2
OCH2CO2H
OCH(CO2H)2
OCH(CO2Et)2
OSO2CF3
5
H
H
0
a
b
d
Assayed at 100 µM. Racemate. c Most active enantiomer (undetermined). Tyrosine ring perfluorinated
Sch em e 7
Sch em e 8
Reagents: () L-Boc-Bpa-OH, EDC, TEA; (b) HCl/HOAc; (c)
succinic anhydride, TEA; (d) LiOH, THF/H2O.
Reagents: (a) Benzyl bromoacetate, KHCO3, acetone or
BnO2CCH2COCl, pyridine or Ms2O, pyridine; (b) H2, Pd/C or LiOH,
THF/MeOH; (c) Dimethyl acetylenedicarboxylate or dibenzyl
acetylenedicarboxylate, TEA, THF, 50 °C; (d) LiOH, MeOH; (e)
H2, Pd/C.
to generate 36, the esters could be directly removed via
saponification to afford diacid 37, or the amine could
be capped with succininc anhydride, leading to triacid
38 after final saponification. Careful comparison of the
13C NMR spectrum of 38 with the corresponding dias-
tereromer 110 prepared from (R)-p-benzoylphenylala-
nine established that only a single diastereomer was
present within the limits of detection. This important
observation confirmed that no racemization of either
chiral center was occurring under the saponification
conditions.
Scheme 8 summarizes the preparation of several
additional tyrosine phoshate bioisostere analogues of 5.
The phenol of 6 could be acylated with benzyl malonyl
chloride and subsequently hydrogenated to provide the
acyl malonate derivative 40. Simple alkylation of phenol
6 with benzyl bromoacetate followed by hydrogenation
gave the carboxymethyl analogue 41. Sulfonylation of
the phenol with methanesulfonic anhydride was em-
ployed to obtain the methylsulfonyl analogue 42. Ho-
mologated malonate analogues were prepared by con-
jugate addition of phenol 6 or 39 to either dimethyl or
dibenzyl acetylenedicarboxylate. The dimethyl maleate
44 was directly saponified to the unsaturated analogue
45, whereas the dibenzyl maleate 43 was hydrogenated
to afford the saturated analogue 46.
Replacement of the phenolic oxygen of malonate
analogue 8 with carbon is outlined in Scheme 9. Pal-
ladium-catalyzed olefination of the triflate derived from
phenol 3 followed by ozonolysis afforded aldehyde 47.23
Knoevenagel condensation installed the unsaturated
malonate moiety of 48. Following amine deprotection
and acylation with succinic anhydride, diester 49 could

602 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Ta ble 2. N- and C-Terminal Analogues
Larsen et al.
a
Assayed at 100 µM.

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 603
Sch em e 9
Sch em e 11
Reagents: (a) TFA/CH2Cl2; (b) succinic anhydride, TEA; (c)
LiOH, THF/MeOH.
Sch em e 12
Reagents: (a) Tf2O, pyridine; (b) vinyl tributyltin, (Ph3P)2PdCl2,
LiCl, DMF, 90 °C; (c) O3, Me2S; (d) dibenzyl malonate, piperidine,
HOAc; (e) HCl/HOAc; (f) succinic anhydride, TEA, (g) LiOH, THF,
MeOH; (h) H2, Pd/C.
Sch em e 10
Reagents: For top, 53-63: (a) CO, Pd(OAc)2, DPPF, BnOH,
80 °C; (b) 2-bromoacetamide, K2CO3, acetone, 40 °C; (c) (i) TFA/
CH2Cl2, (ii) benzyl hydrogen succinate, EDC, DMF; (d) H2, Pd/C,
MeOH. For bottom 53-67: (a) (i) CO, Pd(OAc)2, DPPP, (Me3Si)2NH,
DIPEA, DMF, 90 °C, (ii) HCl/H2O; (b) methyl bromoacetate,
K2CO3, acetone; (c) (i) TFA/CH2Cl2, (ii) succinic anhydride, TEA;
(d) LiOH, THF/MeOH.
Reagents: (a) Boc2O, aq NaOH, dioxane; (b) C5H11NH2, EDC;
(c) CO, Pd(OAc)2, DPPF, TEA, DMF/MeOH, 70 °C; (d) methyl
bromoacetate, K2CO3, acetone; (e) TFA/CH2Cl2; (f) succinic anhy-
dride, TEA; (g) LiOH, THF/MeOH.
moacetamide gave monoamide 61, which was N-depro-
tected and N-acylated with monobenzyl succinate, af-
fording diester 62. Hydrogenolysis then provided the
target acetamido diacid 63. Benzamide analogue 67 was
obtained by a similar route. Carbonylation of iodide 53
in the presence of hexamethyldisilazane followed by
hydrolysis with aq HCl gave benzamide 64.24 Phenol
alkylation with methyl bromoacetate, N-deprotection,
and N-acylation as before gave benzamide monoester
66. Final saponification then afforded benzamide diacid
67.
Insertion of an amino acid residue into 57 is sum-
marized in Scheme 13. The overall route is analogous
to that presented in Schemes 5 and 7. Diester 55 was
N-deprotected prior to coupling with Boc-L-phenylala-
nine to generate 68. Direct saponification provided
diacid 69. Alternatively, the amine could be deprotected
and acylated with monomethyl succinate. The resulting
triester 70 was then saponified to afford the target
triacid 71.
be directly saponified to unsaturated triacid 50 or
hydrogenated to saturated triacid 51.
Salicylate analogue 57 was prepared as illustrated in
Scheme 10. Commercially available m-iodotyrosine 52
was Boc-protected and converted to the n-pentylamide
53 under standard conditions. Palladium-catalyzed car-
boxylation of the iodide in methanol afforded methyl
ester 54. The phenol was alkylated with methyl bro-
moacetate under basic conditions, and the resulting
diester 55 was N-acylated with succinic anhydride after
cleavage of the Boc group. Monoacid 56 was then
saponified to afford triacid 57. A simpler salicylate
analogue 59 could be obtained from 54 by omitting the
phenol alkylation step (Scheme 11).
Monoamide analogues of 57 were prepared as il-
lustrated in Scheme 12. Palladium-catalyzed carboxy-
lation of 53 in the presence of benzyl alcohol provided
benzyl ester 60. Alkylation of the phenol with 2-bro-

604 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Ta ble 3. Dipeptide Analogues
Larsen et al.
% inhibition of phosphatasesa (Ki)
cmpd
R1
R2
PTP1
PTP1B
LAR
SHP-2
32
34
35
37
38
107
108
109
110
111
112
113
114
115
116
117
118
CH2CO2H
CH2CO2H
CH2CO2H
CH2(4-Bz-Ph)
CH2(4-Bz-Ph)
CH2CH2CO2H
CH2CH2CO2H
CH2CO2H
(R)-CH2(4-Bz-Ph)
CH2(4-BnOPh)
CH2(4-(2,5-Cl2Bn)OPh)
CH2(4-MeOPh)
CH2Ph
CH2(4-(2,5-Cl2Bn)OPh)
CH2(4-MeOPh)
CH2Ph
O-tBu
CH2CH2CO2H
n-C5H11
90 (6.0 µM)
10
7
12
25
37
11
71
28
14
50
11
33
28
33
44
45
9
96 (2.0 µM)
95
91
10
24
26
10
11
6
O-tBu
91 (20 µM)
98 (1.2 µM)
96
83
90
54
98 (1.6 µM)
98
98
97 (1.2 µM)
85
90
CH2CH2CO2H
CH2CH2CO2H
O-tBu
98 (0.7 µM)
OCH2Ph
CH2CH2CO2H
CH2CH2CO2H
CH2CH2CO2H
CH2CH2CO2H
CH2CH2CO2H
O-tBu
O-tBu
O-tBu
O-tBu
6
28
33
22
23
27
30
27
0
99
88 (11 µM)
76 (21 µM)
91 (9.0 µM)
83
10
3
CH3
a
Assayed at 100 µM.
Sch em e 13
activity.19 Activity of compounds against TC-PTP, the
known PTP that is structurally most similar to PTP1B,
was also determined. For clarity, only inhibition data
for LAR and SHP-2 are presented here. In general,
however, all the PTP1B inhibitors tested inhibited
cdc25b activity <30% at 100 µM, and none exhibited
significant selectivity between PTP1B and TC-PTP.
Where inhibition kinetics were determined, plots of V
versus S at various concentration of inhibitor were
generated and Ki values were computed using the direct
linear method of Cornish-Bowden. These data are
summarized in Tables 1-4.
We reported recently the discovery that the simple
sulfotyrosyl-containing tripeptide 1 retains essentially
all of the activity (Ki ) 5 µM) of related octapeptidic
PTP1B inhibitors.19 This encouraged us to embark on
a peptidomimetic program wherein the peptidic char-
acteristics of 1 would be attenuated and its chemical
stability bolstered by replacement of the labile sulfate
with a suitable bioisostere. A logical first step was the
removal of the terminal amides, resulting in simple bis-
(amide) tyrosine sulfate 5 that retained significant,
albeit reduced, activity (Ki ) 30 µM, Table 1) against
PTP1. Subsequent replacement of the tyrosine sulfate
moiety of 5 with an O-malonate (8) was based on the
pioneering work of Sikorski,25 who first demonstrated
that O-malonate could serve as a surrogate for phos-
phate, and that of Burke,26 who had already demon-
strated that O-malonyltyrosine could be successfully
incorporated as a tyrosine phosphate mimic into hexapep-
tidic inhibitors of PTP1B. In fact, malonate 8 proved to
be an even more effective inhibitor than 5 and continued
to display competitive inhibition kinetics with a Ki of
11 µM against PTP1B. Of particular interest was the
observation that this simple low molecular weight bis-
(amide) malonate inhibited PTP1B with approximately
10-fold greater potency than it inhibited either LAR or
SHP-2. As anticipated, the corresponding diester 73 was
Reagents: (a) HCl/dioxane; (b) Boc-L-Phe-OH, EDC, HOBt,
TEA, CH2Cl2; (c) LiOH, THF/H2O; (d) methyl succinate, EDC,
HOBt, TEA, CH2Cl2.
Resu lts a n d Discu ssion
All new compounds were tested for their ability to
inhibit a C-terminal truncated, soluble form of recom-
binant rat PTP1 and/or the equivalent soluble form of
recombinant human PTP1B, using p-nitrophenyl phos-
phate (pNPP) as substrate, as previously described.19
Compounds were also tested for inhibition of other
recombinant, purified PTP enzymes as an initial as-
sessment of their specificity. Two PTP enzymes that are
structurally dissimilar to PTP1B (LAR, a membrane-
spanning PTP, and SHP-2, an SH2 domain-containing
PTP involved in insulin signaling36) and a dual specific-
ity phosphatase, cdc25b, were utilized as representa-
tives of three major classes of enzymes with PTP

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 605
Ta ble 4. O-Carboxymethyl Salicylic Acid Analogues
% inhibition of phosphatases (Ki)
% ctrl 2-DOG uptakeb,c
cmpd
R1
R2
PTP1a
PTP1Ba
LARb
SHP-2b
basal
+ins
68 (S,S)
69 (S,S)
70 (S,S)
71 (S,S)
119 (S,R)
CH3
H
CH3
H
OtBu
OtBu
CH2CH2CO2CH3
CH2CH2CO2H
OtBu
0
78
0
0
0
3
0
0
1
2
0
10
0
114
81
225
105
107
72
108
77
83
89
84 (1.1 µM)
93 (0.22 µM)
19
H
a
b
Assayed at 10 µM. Assayed at 100 µM. c Uptake of 2-deoxyglucose into L-6 myocytes expressed as a percent of the control.
Measurements were taken in the absence of insulin (basal) or in the presence of submaximal concentrations of insulin (+ins).
devoid of inhibitory activity, suggesting that the mode
of binding was very similar to that of larger peptides.
A survey of other potential sulfate or malonate
bioisosteres is presented in Table 1. Deleting one of the
malonate carboxyl groups (41) or attaching the mal-
onate to the tyrosine through one of the acyl groups (40)
obliterated activity. Homologation of the malonate (45
and 46) was less deleterious but attenuated activity
nonetheless. Attempted replacement of the phenolic
oxygen with methylene or methine (51 and 50) also
reduced inhibitory activity. This latter observation was
further support for a peptidic binding mode, as it is
known that the phenolic oxygen of tyrosine phosphate
in a peptidic substrate participates in key hydrogen-
bonding interactions with an ordered water molecule.27
Overall, our results are consistent with those of Burke
et al., who have recently reported that related mono-
carboxy analogues and analogues replacing the phenolic
oxygen with carbon are relatively ineffective inhibitors
of PTP1B.16a Installation of a fluorine ortho to the
O-malonate was undertaken to possibly enhance hy-
drogen-bonding interactions with ordered water (20);
however, no augmentation of activity was observed. In
fact, even perfluorination of the O-malonyltyrosine
aromatic ring (21) was ineffective at significantly im-
proving inhibitory potency. Methanesulfonate and tri-
fluoromethanesulfonate analogues 42 and 74 represent
attempts to mimic the sulfate of 5 with neutral func-
tionality. Neither had any significant activity, reinforc-
ing the widely accepted belief that the active site of
PTP1B will only recognize negatively charged molecules.
An investigation of analogues incorporating a modi-
fied tyrosine scaffold was also undertaken to determine
if the natural tyrosine template was optimal (Table 1).
As expected, the configuration of the chiral center was
critical, as indicated by the significantly lower activity
of the enantiomeric analogue 72. Lengthening the
benzyl tether between the aromatic ring and the bis-
(amide) backbone (19) by a single methylene abolished
activity. This is an intriguing finding in light of a recent
observation by Burke that peptidomimetic inhibitors of
PTP1B may be somewhat limited in potential by the
depth to which they can insert into the phosphotyrosine
binding pocket.16a In our case, homologating the tyrosine
moiety by one methylene unit was not beneficial,
although in principle it should have allowed greater
access of the aromatic ring and carboxyl groups to the
phosphate binding pocket.
The most productive modification of the tyrosine ring
entailed transference of one of the malonate carboxyl
groups onto the meta position of the aromatic ring (57),
which resulted in a marked improvement in potency,
particularly against PTP1 (Ki ) 2.8 µM) (Table 1). The
Burke group28 independently reported incorporation of
this novel tyrosine phosphate bioisostere into hexapep-
tides at about the same time as our discovery,29 and
Iversen and Andersen et al.30 have recently reported a
similar tyrosine phosphate bioisostere, 2-(oxalylamino)-
benzoic acid. We found that the new aromatic carboxylic
acid moiety itself was not sufficient for inhibitory
activity, since removal of the O-carboxymethyl group
obliterated activity (59). In fact, simple masking of
either carboxyl of 57 as the corresponding primary
carboxamide (63, 67) was similarly detrimental, estab-
lishing the critical importance of having both carboxyl
groups present.
Although it was expected that the bis(amide) back-
bone would eventually need to be modified to achieve
acceptable pharmacokinetic properties, we decided to
initially retain this functionality to facilitate rapid
modification of the N- and C-termini. Table 2 sum-
marizes our initial work in this area. On the basis of
the prevailing peptidic SAR, it was assumed that the
carboxyl group of the N-terminus would be required,
since it corresponded to the P-1 aspartic acid present
in the best peptidic PTP1B inhibitors. This was con-
firmed with ester and amide analogues 75 and 76, each
of which had substantially attenuated activity relative
to acid 8. A series of carboxylic acids was thus generated
off the N-terminus (77-86) to investigate the effect of
chain length, substitution, and conformational restric-
tion. Unfortunately, none of the new analogues exhib-
ited improved activity relative to the simple succinic
acid of 8. Attention was then focused on the C-terminal
n-pentyl amide. Chain length, simple substitution, and
incorporation of heteroatoms or aromatic rings were all
investigated (87-106). To our surprise, although re-
moval of a single methylene unit was quite detrimental
to activity (88), larger groups were not more effective
(e.g., 87, 89, 90), suggesting that a shallow pocket of
defined length was being accessed. Consistent with this
hypothesis was the lack of improvement with the

606 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
addition of aromatic ring(s), both substituted and un-
substituted. Preliminary attempts to add hydrophilic
functionality (e.g., 96, 102-104) were even less encour-
aging.
116), and that is consistent with the known preference
of SHP-2 for peptidic substrates with lipophilic residues
N-terminal to the phosphotyrosine.37 The corresponding
N-Boc derivatives again retained activity (37, 115-118),
demonstrating for the first time in this series that
effective inhibition of PTP1 could be achieved in the
absence of an N-terminal carboxyl group, a finding of
obvious importance from a drug development stand-
point.
It was of considerable interest to us to confirm that
our small malonate PTP1B inhibitors bound in a mode
similar to that of larger peptidic tyrosine phosphate
substrates, because enzyme/substrate structural infor-
mation was available that might guide further analogue
design. Barford had recently published an X-ray struc-
ture of a catalytically inactive C215-S mutant of PTP1B
bound to the hexapeptidic substrate DADEpYL-NH2.27
Recognizing that 8 was highly analogous to the central
tripeptide (EpYL) of this substrate, it was logical to
assume that introduction to 8 of either a C-terminal
carboxamide or a second N-terminal carboxylic acid
analogous to the hexapeptidic P-2 aspartic acid ought
to augment binding, as both of these functionalities were
reported by Barford to make hydrogen-bonding interac-
tions with the enzyme. Analogues 105 (Table 2) and 34
(Table 3) were prepared to test these assumptions, and
each of these analogues indeed proved to be significantly
more active (Ki ) 2 µM) than 8 (Ki ) 12 µM). Although
these analogues were now the most active to date and
useful for supporting the proposed mode of binding,
neither could be considered a step forward toward a
viable drug. An attempt to replace the C-terminal
primary carboxamide of 105 with hydroxyl (106) unfor-
tunately attenuated activity. Fortunately, we subse-
quently noted that the terminal carboxylic acid moiety
of 34 was not absolutely required for effective inhibition
of PTP1. The simple N-Boc derivative 32 remained more
active than 8, suggesting that the new amide moiety
was in part responsible for the improved binding affin-
ity. N-Cbz and N-alkanoyl derivatives 109 and 35
indeed were similarly active (Table 3).
Table 4 summarizes biological data for analogues that
combine the most active tyrosine phosphate bioisostere
(from 57) with the “optimized” N-terminus of 114. The
two elements proved to be complementary, as the
resulting analogue 71 inhibited PTP1B with a potency
exceeding either of the forerunners (Ki ) 0.22 µM). Of
particular interest was the observation that this im-
proved potency vs PTP1B was associated with an es-
sentially complete loss of activity against LAR and SHP-
2. The simple (S,S)-N-Boc derivative 69 also benefited
from the new tyrosine phosphate bioisostere, achieving
a Ki of 1.1 µM, the most potent analogue of this series
lacking any N-terminal carboxyl group. The relative
configuration of the chiral centers was again confirmed
to be important by the markedly lower potency of the
analogue 119 prepared from (R)-Boc-Phe.
Unfortunately, none of the new analogues exhibited
reproducible augmentation of insulin-stimulated 2-deox-
yglucose (2-DOG) uptake into intact cells (L6 myocytes,
3T3-L1 adipocytes, primary rat adipocytes) (representa-
tive data presented in Table 4). This is not altogether
surprising, considering the impediment to cell penetra-
tion that would be expected to result from the charge
associated with multiple carboxyl groups. In fact, it was
demonstrated that a number of analogues from this
series are extremely poor at penetrating a Caco-2 cell
monolayer,32 with permeability coefficients generally
less than 5 nm/s (data not shown). Prodrug esters were
investigated as a logical recourse, two of which (68 and
70) indeed exhibited greatly enhanced penetration
(permeability coefficients of 680 and 136 nm/s, respec-
tively). Although 68 remained inactive at stimulating
2-DOG uptake into L-6 myocytes, 70 elicited an ap-
proximate doubling of 2-DOG uptake at a concentration
of 100 µM (Table 4). Compound 70 caused a large
increase in basal 2-DOG uptake by L6 myocytes, and
this is consistent with the hypothesis that, in the
absence of insulin, the insulin receptor tyrosine kinase
is not entirely quiescent and PTP1B is required to
dampen spontaneous signaling. The large effect of 70
on basal 2-DOG uptake was subtracted when the effect
of 70 on insulin-dependent 2-DOG uptake was com-
puted, and this results in an apparent lack of effect of
70 in the presence of insulin. In fact, in a typical
experiment (n ) 3) in which 70 was tested in this way,
uptake in the presence of insulin (10 nM) but absence
of 70 [50.6 ( 0.5 pmol min-1 (mg of protein)-1] was
increased by 70 to a value [72.7 ( 0.3 pmol min-1 (mg
of protein)-1] that was similar to the maximal observed
with insulin (300 nM) alone [79.5 ( 1.3 pmol min-1 (mg
of protein)-1].
A second literature report provided a clue toward
further improving the physical properties of 34 without
sacrificing activity. Zhang reported that replacement of
the P-1 glutamic acid residue of PTP1B substrate
AcDADEpYLIPQQG with the photolabile amino acid
p-benzoylphenylalanine (Bpa) did not significantly alter
its susceptibility to dephosphorylation by PTP1, a
surprising observation in light of the markedly different
physical properties of the Bpa residue relative to
glutamic acid.31 Therefore, analogue 38 was prepared
to test whether a similar replacement of the aspartic
acid of 34 with L-Bpa would be viable. Importantly, we
observed an increase in potency, achieving for the first
time submicromolar activity against PTP1B (Ki ) 0.7
µM) (Table 3). As expected, the configuration of the new
chiral center was important, as the corresponding
analogue prepared from D-Bpa (110) was approximately
2 orders of magnitude less active. Subsequent SAR
quickly determined that simple phenylalanine analogue
114 was just as effective as 38 and had the advantage
of substantially lower molecular weight. Paring further
down to the alanine derivative 118 eroded activity. Of
particular interest was the improvement in specificity
for PTP1 vs SHP-2 of 114 relative to 38 (Table 3). This
at least suggests that higher lipophilicity may be
detrimental to selectivity, a conclusion that is supported
by other comparisons in this work (e.g., 109 is less
specific for PTP1 than is 32; 115 is less specific than
The effect of 70 on 2-DOG uptake was accompanied
by increased levels of IR and IRS-1 and -2 phosphory-
lation,19 evidence that inhibition of PTP1B was occur-
ring within the cell, even though 70 itself is devoid of

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 607
F igu r e 1. X-ray structure (2.2 Å resolution) of 69 (white) bound to PTP1B (green). The enzyme backbone is shown as a ribbon
diagram with key residues presented in detail and labeled. Heteroatoms are colored by type (O, red; N, blue). Bound water molecules
are presented as red spheres. Selected hydrogen-bonding interactions with enzyme are depicted with dashed lines (distances in
angstroms).
inhibitory activity. Triester 70 also augmented 2-DOG
uptake into and IR and IRS-1 phosphorylation of an
insulin-resistant 3T3-L1 adipocyte model.19 The triester
is likely cleaved enzymatically in cells to an active
component(s), because we demonstrated time-dependent
hydrolysis of 70 to a mixture of mono- and diacids by
porcine hepatic esterase (no triacid 71 was detected).
Although not all of the components of this mixture could
be identified unambiguously without independent syn-
theses, the mixture itself was shown to be active at
inhibiting PTP1B, and inhibition was proportional to
the amount of diacid product.19
The mode of binding of triacid 71 was eventually
confirmed by solving an X-ray cocrystal structure with
a C-terminal-truncated form of PTP1B.19 Since dissec-
tion of the N-terminal carboxyl group was likely to be a
requirement for further development of this series, it
was important to determine what effect, if any, this
structural modification would have on the binding mode.
Thus, 69 was selected for cocrystallization studies with
PTP1B. The overall structure of the PTP1B compound
F igu r e 2. Schematic representation of the hydrogen-bonding
interactions between 69 (red) and PTP1B (black). Bound water
69 complex proved to be very similar to the previously
reported structure of PTP1B with compound 7119 (Fig-
ures 1 and 2; coordinates have been deposited with the
PDB under the file name 1J F7). This was not unex-
pected, as these two compounds only differ in the nature
of their N-terminal substituent. As with 71, the binding
of compound 69 is accompanied by closure of the WPD
loop (comprising of residues 179-189) of the enzymes
catalytic site. The peptide backbone portion of both
bound inhibitors forms an extended â-strand conforma-
tion closely resembling that seen previously for peptidic
substrates.27 These compounds maintain two conserved
hydrogen bonds between the Asp48 side chain and the
main chain nitrogens on either side of the central
O-carboxymethyl salicylic acid tyrosine phosphate mimic
(P and P + 1 positions) and a third between the main
chain nitrogen of Arg47 and the Boc carbonyl of the
inhibitor at the P-1 position. The phenyl ring of the
phosphotyrosine (pTyr) mimic also makes hydrophobic
molecules are labeled as W. All distances are in angstroms,
and only interactions of 3.1 Å or less are shown.
packing interactions with the side chains of Tyr46,
Val49, Ala217, Ile219, Gln262, and Phe181. In addition,
the C-terminal pentyl chains (P + 1) of both compounds
lay in a shallow hydrophobic pocket and form hydro-
phobic contacts with the side chains of Val49, Ile219,
and Gln262.
In the PTP1B-pTyr peptide crystal structures, two of
the phosphate oxygen atoms of the pTyr residue make
two hydrogen bonds, each to the main chain amides of
Ser216, Ala217 and Ile219, Gly220, respectively.27 The
phosphate mimic headgroups of both compounds 69 and
71 are positioned somewhat closer to the WPD loop than
the phosphate group of the substrate, resulting in the
loss of all four hydrogen bonds. These interactions with
the backbone amides are instead formed by new struc-
turally bound water molecules. These solvent molecules

608 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
Sch em e 14. Key Analogues in the Evolution of the
form a network of hydrogen bonds between residues of
the phosphate binding site (the amides of Ser216,
Ile219, and Gly220, the NH1 of Arg221) and the ether
oxygen of O-carboxymethyl salicylic acid headgroup
itself (Figure 2). The positioning of the headgroup closer
to the WPD loop also results in the displacement of a
bound water molecule hydrogen bonded to Gln266 in
the PTP1B-substrate structures with compensatory
hydrogen bonds being formed by headgroup oxygens
(Figure 2).
Tripeptide PTP1B Inhibitor 1
The terminal carboxylate of the O-carboxymethyl
salicylic acid headgroup makes a series of five hydrogen
bonds to the main chain nitrogen of Phe182, the side
chain amide of Gln266, the side chain NE1 and main
chain nitrogen of Arg221, and to one of the ordered
waters located in the phosphate binding site. The
o-carboxyl substituent of the inhibitor in turn forms
hydrogen bonds to the side chain of Lys120 (3.1 Å) and
to two water molecules, including the one mentioned
above. However, there is no significant interaction
observed between the o-carboxylate and the side cain
of Asp181 as was apparent in the PTP1B-71 complex,
where they share a proton. This difference is probably
due to the fact that the crystals of the PTP1B-69
complex were grown at a somewhat higher pH (8.0 vs
6.5), resulting in the Asp181 side chain carboxylate
being unprotonated and thus unable to interact with
the inhibitor.
The only other significant difference in binding be-
tween compounds 69 and 71 is observed at the N-
terminus, where the P-2 carboxylic acid function of
compound 71 is replaced by a hydrophobic N-Boc group.
As a consequence of the loss of a hydrogen bond between
the terminal carboxylate of compound 71 and the Arg47
side chain, there is observed a concerted repositioning
of both Arg47 and P-1 Phe side chains by about 3 Å.
Yet despite this movement, both the hydrophobic in-
teractions between these two side chains and the
hydrogen bond between the P-1 carbonyl and the Arg47
main chain amide are maintained. This again demon-
strates, as has been previously observed,19,34 the con-
formational plasticity of the Arg47 side chain to accom-
modate a variety of N-terminal ligand structures.
Although there are two PTP1B molecules in the
crystal unit cell, only one was seen to have a bound
inhibitor. The binding site of the other PTP1B molecule
is effectively blocked by crystal contacts from a sym-
metry-related PTP1B molecule. In particular, amino
acids 236-240 in the symmetry-related enzyme make
similar contacts with the binding site to those seen in
the peptide substrate crystal structures. The symmetry
related Lys233 is positioned equivalently to a substrate
phosphotyrosine and is held in place by hydrogen bonds
from the binding site Asp48 to the backbone amides of
Lys233 and Asp240. The lysine, however, does not
extend down to the phosphate cradle, which is occupied
by a sulfate ion, but instead hydrogen bonds to the side
chain of Gln262.
with Ki values in the range of 5 µM. Inhibitory activity
was subsequently determined to reside unexpectedly
within the N-terminal tripeptidic sequence Ac-Asp-Tyr-
(SO3H)-Nle-NH2 (Ki ) 5 µM). An analogue program was
launched to attenuate the peptidic character of this lead
and to enhance its potency. Modifications in the early
phase of this work included a survey of phosphate
mimics, alteration of the core tyrosine template, N- and
C-terminal replacements with non-amino acid compo-
nents, and insertion of specific amino acids at the P-1
position to evaluate the mode of binding. Key analogues
that guided the evolution of the SAR are summarized
in Scheme 14. The most significant analogue arising
from this work was 71, which possesses submicromolar
affinity for PTP1B (Ki ) 0.22 µM) without significantly
inhibiting LAR or SHP-2 at concentrations up to 100
µM. Furthermore, it was demonstrated that a triester
prodrug of this molecule (70) enhances insulin signaling
in two different cell lines. Key elements of our SAR
study that could guide future inhibitor design in this
area include the following: confirmation of the remark-
able effectiveness and PTP1B specificity of the novel
tyrosine phosphate mimic O-carboxymethyl salicylic
acid, demonstration that the tyrosine template is opti-
mal relative to a number of closely related structures,
successful replacement of the P-1 aspartic acid present
in peptidic inhibitors with the neutral and lipophilic
phenylalanine residue, and the observation that the
N-terminal carboxyl group can be jettisoned altogether
with retention of significant activity. Solution of the
X-ray cocrystal structure of the neutral N-terminal
analogue 69 bound to PTP1B revealed that the (Boc)-
Phe N-terminus interacts with the enzyme primarily
through the urethane carbonyl group and through
hydrophobic interactions with the aromatic ring. Ad-
ditional SAR studies encompassing more potent neutral
Con clu sion s
Directed screening of the Pharmacia compound col-
lection for reversible competitive inhibitors of PTP1B
bearing potential phosphotyrosine mimics resulted in
the identification of sulfotyrosyl-containing octapeptides

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 609
leaving a solid that was purified by preparative reverse phase
HPLC on a Vydac C-18 column (27.5 × 250 mm) using a water/
acetonitrile gradient, each phase containing 0.1% TFA. Clean
fractions, as determined by analytical HPLC, were pooled, and
the acetonitrile was evaporated under reduced pressure. The
aqueous solution was then lyophilized: 1H NMR (DMSO) δ
8.03 (d, J ) 8 Hz, 1 H), 7.79 (t, J ) 7 Hz, 1 H), 7.06 (d, J ) 7
Hz), 7.01 (d, J ) 7 Hz, 2 H), 4.33 (m, 1 H), 2.99 (m, 2 H), 2.87
(dd, J ) 6, 13 Hz, 1 H), 2.68 (dd, J ) 8, 13 Hz, 1 H), 2.3 (m, 4
H), 1.1-1.3 (m, 6 H), 0.83 (t, J ) 7 Hz, 3 H); ES MS m/z
(negative ion, rel intens) 429 (100), 214 (20); HRMS (FAB)
calcd for C18H26N2O8S + H 431.1488, found 431.1473.
Ben zyl 4-{[(1S)-1-(4-H yd r oxyb en zyl)-2-oxo-2-(p en t yl-
a m in o)eth yl]a m in o}-4-oxobu ta n oa te (6). The Boc group of
3 was removed as described in the preparation of 4. EDC (368
mg, 1.92 mmol) was added to a 0 °C solution of the crude amine
hydrochloride (500 mg, 1.74 mmol), monobenzyl succinate (368
mg, 1.92 mmol), and triethylamine (270 uL, 1.92 mmol) in
methylene chloride (7 mL). The reaction was stirred at room
temperature for 24 h. After dilution with ethyl acetate (40 mL),
the mixture was washed successively with 0.5 M HCl, water,
and sat. aq sodium bicarbonate (20 mL each). The organic
phase was dried over magnesium sulfate and concentrated to
a white amorphous solid (694 mg, 91%) that was analytically
pure. [R]25D -5.4° (c 0.017, methanol); 1H NMR (CDCl3) δ 7.33
(m, 5 H), 7.05 (d, J ) 8 Hz, 2 H), 6.74 (d, J ) 8 Hz, 2 H), 6.21
(d, J ) 8 Hz, 1 H), 5.90 (bt, J ) 7 Hz, 1 H), 5.68 (bs, 1 H),
5.13, 5.09 (ABq, J ) 14 Hz, 2 H), 4.54 (m, 1 H), 3.12 (q, J ) 7
Hz, 2 H), 3.06, 2.90 (ABqd, J ) 7, 14 Hz, 2 H), 2.4-2.85 (m, 4
H), 1.1-1.4 (m, 6 H), 0.86 (t, J ) 7 Hz, 3 H).
Di-ter t-bu tyl 2-{4-[(2S)-2-{[4-(Ben zyloxy)-4-oxobu tan oyl]-
a m in o}-3-oxo-3-(p e n t yla m in o)p r op yl]p h e n oxy}m a lo-
n a te (7). A solution of di-tert-butyl diazomalonate21 (396 mg,
1.63 mmol) in benzene (2 mL) was added over 6 h to an 80 °C
mixture of 6 (342 mg, 0.776 mmol) and rhodium(II) acetate (7
mg) in benzene (33 mL) via syringe pump, during which time
most of the starting material went into solution. The blue-
green solution was stirred at that temperature for an ad-
ditional hour and then overnight at room temperature. The
reaction was filtered through a medium frit and then concen-
trated in vacuo. Flash chromatography (80 g silica, 70% ethyl
acetate/hexane) provided the title material (232 mg, 46%) as
a foam: 1H NMR (CDCl3) δ 7.33 (m, 5 H), 7.12 (d, J ) 9 Hz,
2 H), 6.89 (d, J ) 9 Hz, 2 H), 6.10 (bd, J ) 8 Hz, 1 H), 5.81 (bt,
J ) 7 Hz, 1 H), 5.12, 5.08 (ABq, J ) 12 Hz, 2 H), 4.94 (s, 1 H),
4.52 (m, 1 H), 3.1 (m, 3 H), 2.6-2.95 (m, 3 H), 2.45 (m, 2 H),
1.49 (s, 18 H), 1.1-1.4 (m, 6 H), 0.86 (t, J ) 7 Hz, 3 H).
N-terminal analogues, bioisosteric replacement of the
O-carboxymethyl salicylic acid carboxyl groups, and
alteration of the bis(amide) backbone will be the subject
of future reports.
Exp er im en ta l Section
All melting points (mp) were obtained on a capillary melting
point apparatus and are uncorrected. Proton magnetic reso-
nance spectra were recorded on a Bruker AM-300 or AM-400
spectrometer in the deuterated solvents indicated. Chemical
shifts were recorded in parts per million (δ scale) and are
reported relative to internal tetramethylsilane. 13C NMR
spectra were recorded on a Bruker AM-300 spectrometer at
75.4 MHz. Flash column chromatography separations were
carried out using EM Science silica (mesh 230-400). Electron
impact (EI) mass spectra were obtained with an ionization
voltage of 70 eV. Alternatively, ionization was achieved by fast
atom bombardment (FAB) or electrospray (ES+ or ES-).
Reagents and solvents were purchased from common suppliers
and were used as received. All nonaqueous reactions were run
under a nitrogen atmosphere. All starting materials were
commercially available unless otherwise noted.
ter t-Bu t yl (1S)-1-(4-H yd r oxyb en zyl)-2-oxo-2-(p en t yl-
a m in o)eth ylca r ba m a te (3). To a 0 °C mixture of Boc-L-
tyrosine (2.04 g, 7.25 mmol) and amylamine (0.93 mL, 7.98
mmol) in methylene chloride (30 mL) was added 1-[3-(dim-
ethylamino)propyl]-3-ethylcarbodiimide (EDC) (1.53 g, 7.98
mmol). The white mixture was stirred at 0 °C for 5 min and
at room temperature for 23 h. The resulting solution was
diluted with methylene chloride (30 mL) and washed succes-
sively with 0.5 M HCl (40 mL), water (20 mL), and sat. aq
sodium bicarbonate (25 mL). The organic phase was dried over
magnesium sulfate and concentrated to a foam (1.84 g, 73%)
that was sufficiently pure to carry into the next step. An
analytical sample could be obtained by flash chromatography
(1/1 ethyl acetate/hexane) as a glass: 1H NMR (CDCl3) δ 7.01
(d, J ) 7 Hz, 2 H), 6.74 (d, J ) 7 Hz, 2 H), 5.90 (bt, 1 H), 5.17
(bd, 1 H), 4.21 (bq, J ) 7 Hz, 1 H), 3.13 (m, 2 H), 2.93 (m, 2
H), 1.41 (s, 9 H), 1.1-1.4 (m, 6 H), 0.85 (t, J ) 7 Hz, 3 H).
4-{[(1S)-1-(4-H yd r oxyb en zyl)-2-oxo-2-(p en t yla m in o)-
et h yl]a m in o}-4-oxob u t a n oic Acid (4). To a solution of 3
(5.28 g, 15.1 mmol) in dioxane (40 mL) chilled in an ice bath
was added a freshly prepared solution of HCl in dioxane (about
3 M, 25 mL). The solution was then stirred at rt for 1.5 h. The
solution was diluted rapidly with ether (350 mL) until no
further precipitation was evident. The mixture was stirred
vigorously until all insoluble material was adhering to the
sides of the flask. After decanting the supernatant, the crude
material was taken up in more ether (200 mL) and sonicated
until it was a fine solid (required about 1 h). Filtration gave
the amine hydrochloride as a hygroscopic white powder (4.32
g, approximately 100%).
2-{4-[(2S )-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-oxo-3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon ic Acid (8). Trifluo-
roacetic acid (5 mL) was added to a solution of 7 (225 mg, 0.344
mmol) in methylene chloride (5 mL) with ice-bath chilling. The
solution was stirred at room temperature for 2 h. Concentra-
tion in vacuo afforded a light amber foam. This was dissolved
in ethyl acetate and concentrated in vacuo three times to get
rid of traces of trifluoroacetic acid. The residue was then
dissolved in methanol (10 mL) and subjected to three cycles
of evacuation and nitrogen purge at 0 °C before the introduc-
tion of 10% Pd/C (20 mg). The mixture was then hydrogenated
at 1 atm for 1.5 h. The mixture was filtered through Celite
and concentrated in vacuo. The crude glass was taken up in
methylene chloride (40 mL) and sonicated until it was all
suspended. Filtration gave a brittle white amorphous solid
Triethylamine (307 µL, 2.2 mmol) was added to a 0 °C
mixture of the crude amine hydrochloride from above (287 mg,
1.0 mmol) in methylene chloride (4 mL), causing rapid dis-
solution. To this solution was added succinic anhydride (100
mg, 1.0 mmol), and the reaction was stirred at room temper-
ature for 25 h. The reaction was then diluted with ethyl acetate
(20 mL) and washed successively with 0.5 M HCl (10 mL) and
brine (10 mL). The organic phase was dried over magnesium
sulfate and concentrated to a viscous oil (350 mg, approx 100%)
that solidified on standing: 1H NMR (DMSO) δ 9.1 (s, 1 H),
7.98 (d, J ) 7 Hz, 1 H), 7.74 (t, J ) 6 Hz, 1 H), 6.96 (d, J ) 7
Hz, 2 H), 6.60 (d, J ) 7 Hz, 2 H), 4.30 (m, 1 H), 2.9-3.1 (m, 2
H), 2.8 (dd, J ) 7, 14 Hz, 1 H), 2.60 (dd, J ) 8, 14 Hz, 1 H),
2.3 (m, 4 H), 1.1-1.4 (m, 6 H), 0.83 (t, J ) 7 Hz, 3 H). Anal.
(C18H26N2O5)·0.44H2O) C, H, N.
(116 mg, 88% overall from 7): mp 117-120 °C, dec; [R]25
)
D
-0.7° (c 0.0058, methanol); 1H NMR (CD3OD) δ 8.13 (bd, J )
8 Hz, 1 H), 7.81 (bt, J ) 7 Hz, 1 H), 7.17 (d, J ) 8 Hz, 2 H),
6.90 (d, J ) 8 Hz, 2 H), 5.23 (s, 1 H), 4.48 (m, 1 H), 3.1 (m, 3
H), 2.81 (dd, J ) 8, 14 Hz, 1 H), 2.3-2.6 (m, 4 H), 1.2-1.5 (m,
6 H), 0.89 (t, J ) 7 Hz, 3 H); MS (FAB) m/z (rel intensity) 453
(M + H, 47), 453 (47), 238 (15), 194 (17), 136 (12), 133 (17),
101 (12), 88 (99), 86 (30), 55 (15), 43 (22). Anal. (C21H28N2O9·
0.6H2O) C, H, N.
4-Oxo-4-({(1S)-2-oxo-2-(p en t yla m in o)-1-[4-(su lfooxy)-
ben zyl]eth yl}a m in o)bu ta n oic Acid (5). A solution of 4 (100
mg, 0.29 mmol) and pyridine-sulfur trioxide complex (500 mg)
in DMF:pyridine (1:1, 10 mL) was stirred under nitrogen at
rt for 20 h. NMR analysis of an aliquot indicated complete
conversion to product. Solvent was removed under vacuum,
Ben zyl (1S)-1-(4-Hyd r oxyben zyl)-2-oxo-2-(p en tyla m i-
n o)eth ylca r ba m a te (10b). To a mixture of Cbz-Try-OH (9b)-
(2 g, 6.3 mmol) in CH2Cl2 (75 mL) and DMF (5 mL) at 0 °C

610 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
was added EDC (1.21 g, 6.3 mmol). After a few minutes,
amylamine (0.74 mL, 6.3 mmol) was added, and the mixture
was warmed to room temperature and stirred for 4.5 h. HCl
(10%, 50 mL) was added, and the phases were separated. The
organic phase was washed with sat. NaCl (30 mL), dried
(MgSO4), and concentrated. The residue was purified by flash
chromatography (75 g SiO2, 50% EtOAc/hexane) to give 1.7 g
(68%) of a white solid: 1H NMR (CDCl3) δ 7.34 (m, 5 H), 7.06
(d, 2 H), 6.74 (d, 2 H), 5.53 (br s, 1 H), 5.35 (br s, 1 H), 5.09 (s,
2 H), 5.05 (br s, 1 H), 4.25 (q, 1 H), 3.14 (q, 2 H), 3.15 (dd, 1
H), 2.92 (dd, 1 H), 1.14-1.35 (m, 6 H), 0.86 (t, 3 H).
Diben zyl 2-{4-[(2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-
oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon a te (11a ). To
a stirring solution of 3 (2.0 g, 5.71 mmol) in acetone (50 mL)
was added K2CO3 (1.57 g, 11.42 mmol) at ambient tempera-
ture. To the resulting heterogeneous mixture was added
dibenzyl bromomalonate (2.89 g, 6.28 mmol), and the mixture
was stirred at ambient temperature overnight. The resulting
amber suspension was diluted with H2O (100 mL) and
extracted with EtOAc (2 × 100 mL). The combined organic
layers were dried over MgSO4, and the solvent was removed
in vacuo. The residue was purified via flash chromatography
(2: 1 EtOAc/hexane) to afford 1.26 g (35%) of a white solid:
1H NMR (CDCl3) δ 0.84 (t, 3 H), 1.16-1.38 (m, 8 H), 1.39 (s,
9 H), 2.96 (m, 2 H), 3.13 (dd, 2 H), 4.21 (q, 1 H), 5.20 (s, 4 H),
5.08 (m, 1 H), 5.23 (s, 1 H), 5.85 (t, 1 H), 6.83 (d, 2 H), 7.07 (d,
2 H), 7.25 (m, 10 H).
Dieth yl 2-{4-[(2S)-2-{[(Ben zyloxy)ca r bon yl]a m in o}-3-
oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon a te (11b). To
a mixture of 10b (200 mg, 0.5 mmol) and K2CO3 (146 mg, 1.0
mmol) in acetone (1.5 mL) was added diethyl chloromalonate
(0.17 mL, 1.0 mmol). The mixture was stirred vigorously for
18 h. The mixture was partitioned between EtOAc (10 mL)
and H2O (5 mL). The organic phase was washed with H2O and
sat. NaCl. After drying (MgSO4), the solvent was removed
under reduced pressure. The residue was purified by flash
chromatography (40% EtOAc/hexane) to provide 140 mg (49%)
of a white solid: 1H NMR (CDCl3) δ 7.33 (m, 5 H), 7.10 (d, 2
H), 6.88 (d, 2 H), 5.55 (t, 1 H), 5.31 (br s, 1 H), 5.14 (s, 1 H),
5.08 (s, 2 H), 4.30 (m, 5 H), 3.12 (m, 3 H), 2.93 (ab q, 1 H),
1.30 (m, 12 H), 0.86 (t, 3 H); MS (ES-) 541. Also obtained off
the column was a small amount of the R-chloromalonate 15
(10 mg): 1H NMR (CDCl3) δ 7.33 (m, 5 H), 7.11 (m, 4 H), 5.55
(br s, 1 H), 5.25 (m, 1 H), 5.08 (s, 2 H), 4.31 (m, 4 H), 3.12 (q,
2 H), 2.98 (m, 2 H), 1.10-1.40 (m, 12 H), 0.86 (t, 3 H); MS
(ESI+) for C29H37ClN2O8 m/z 577 (M + H)+; MS (ES-) for
C29H37ClN2O8 m/z 575 (M - H)-.
Dib en zyl 2-{4-[(2S)-2-Am in o-3-oxo-3-(p en t yla m in o)-
p r op yl]p h en oxy}m a lon a te Hyd r och lor id e (12a ). To a
stirring solution of 11a (2.85 g, 4.5 mmol) in HOAc (25 mL) at
ambient temperature was added 1.5 N HCl/HOAc (20 mL),
and the resulting solution was stirred at ambient temperature
for 2 h. The solvent was evaporated to 30 mL, and the solution
was triturated with Et2O (400 mL). The resulting turbid
suspension was stirred at ambient temperature for 30 min,
sonicated, and filtered to afford 2.50 g (98%) of 12a as a white
solid: 1H NMR (DMSO) δ 0.80 (t, 3 H), 1.18 (m, 8 H), 2.93 (m,
3 H), 3.04 (m, 1 H), 3.87 (t, 1 H), 5.20 (s, 4 H), 5.83 (s, 1 H),
6.91 (d, 2 H), 7.13 (d, 2 H), 7.32 (m, 10 H), 8.39 (t, 1 H) (NH2
not observed).
collected to provide 2.0 g (83%) of 12b as an off-white solid:
1H NMR (DMSO) δ 8.39 (t, J ) 7 Hz, 1 H), 8.23 (bs, 3 H), 7.14
(d, J ) 9 Hz, 2 H), 6.90 (d, J ) 9 Hz, 2 H), 5.63 (s, 1 H), 4.20
(m, 4 H), 3.88 (t, J ) 7 Hz, 1 H), 3.05 (m, 1 H), 2.93 (m, 3 H),
1.19 (t, J ) 7 Hz, 6 H), 1.1-1.4 (m, 6 H), 0.82 (t, J ) 7 Hz,
3 H).
Gen er a l P r oced u r e for Rea ction of 12a w ith An h y-
d r id es To Affor d Am id es 13a . To a stirring solution of 12a
(0.20 g, 0.35 mmol) in CH2Cl2 (10 mL) was added triethylamine
(78 mg, 0.77 mmol) at 0 °C. The requisite anhydride (0.35
mmol) was added in one portion and the resulting solution
was allowed to stir for 16 h while warming to ambient
temperature. The solution was diluted with CH2Cl2 (50 mL)
and washed with 10% HCl/H2O (2 × 50 mL). The combined
organic phases were dried over MgSO4 and solvent removed
in vacuo to afford material suitable for subsequent transfor-
mations.
Gen er a l P r oced u r e for H yd r ogen a t ion of Ben zyl
Ester s 13a To Affor d Acid s 14. To a solution of the requisite
ester in MeOH (∼0.02 M) at ambient temperature was added
10% Pd/C (10 wt %), and the resulting mixture was hydroge-
nated at atmospheric pressure for 3 h. The mixture was filtered
through Celite and solvent removed to afford analytically pure
material.
Rep r esen ta tive P r oced u r e for Con ver sion of 12b to
14. See procedure for compound 76.
2-{4-[3-[(3-Ca r b oxyp r op a n oyl)a m in o]-4-oxo-4-(p e n -
tyla m in o)bu tyl]p h en oxy}m a lon ic a cid (19) was prepared
from racemic N-Boc-homotyrosine35 by procedures analogous
to those described for the transformation of 2 to 14 (Scheme
3). Preparative reverse phase HPLC, using the same conditions
as reported for the purification of 20, afforded 19 as a white
solid: 1H NMR (400 MHz, DMSO-d6) δ 8.07 (d, J ) 8 Hz, 1
H), 7.76 (t, J ) 6 Hz, 1 H), 7.06 (d, J ) 9 Hz, 2 H), 6.80 (d, J
) 9 Hz, 2 H), 4.61 (s, 1 H), 4.16-4.15 (m, 1 H), 3.06-2.98 (m,
2 H), 2.49-2.37 (m, 6 H), 1.92-1.82 (m, 1 H), 1.77-1.66 (m, 1
H), 1.40-1.35 (m, 2 H), 1.27-1.20 (m, 4 H), 0.84 (t, J ) 7 Hz,
3 H); MS (ESI-) for C23H31NO9
retention time ) 27 min.
CO2 m/z 421.2; HPLC
-
2-{4-[2-[(3-Ca r boxyp r op a n oyl)a m in o]-3-oxo-3-(p en tyl-
a m in o)p r op yl]-2-flu or op h en oxy}m a lon ic a cid (20) was
prepared from racemic N-Boc-3-fluorotyrosine by procedures
analogous to those described for the transformation of 2 to 14
(Scheme 3). Following preparative reverse phase HPLC, 20
was obtained as a hygroscopic white solid after lyophiliza-
tion: 1H NMR (300 MHz, DMSO-d6) δ 8.08 (d, J ) 8 Hz, 1 H),
7.82 (br t, 1 H), 7.07 (d, J ) 12 Hz, 1 H), 6.96-6.89 (m, 2 H),
5.33 (s, 1 H), 4.39-4.32 (m, 1 H), 3.06-2.94 (m, 2 H), 2.90-
2.84 (m, 1 H), 2.99-2.63 (m, 1 H), 2.35-2.21 (m, 4 H), 1.46-
1.11 (m, 6 H), 0.82 (t, J ) 7 Hz, 3 H); MS (FAB) m/z 471 (MH+),
471, 193, 171, 167, 153, 135, 133, 121, 103, 89; HRMS (FAB)
calcd for C21H27FN2O9 + H 471.1779, found 471.1797. Anal.
(C21H27FN2O9·3.0H2O) C, N; H: calcd, 6.34; found, 5.45.
P r ep a r a tive RP HP LC Con d ition s.
Column: Rainin Dynamax C8, 8 µm particle size, 60 Å pore
size, 21.4 × 250 mm.
Solvent: isocratic with 20% MeCN/H2O/0.1% TFA, 6 mL/
min
. λ ) 210 nm.
Injection volume ) 2000 µL.
Dieth yl 2-{4-[(2S)-2-Am in o-3-oxo-3-(p en tyla m in o)p r o-
p yl]p h en oxy}m a lon a te Hyd r och lor id e (12b). To a solution
of 11b (2.9 g, 5.3 mmol) in absolute EtOH (100 mL) and THF
(10 mL) was added 10% Pd/C (0.29 g, moistened with absolute
EtOH). The mixture was hydrogenated (40 psi) for 1 h. The
mixture was filtered through Celite and concentrated under
reduced pressure. The residue was dissolved in a 1 M solution
of HCl in HOAc (10 mL). After stirring for several minutes,
the mixture was concentrated to 2-3 mL. A large amount of
Et2O was added, and the mixture was cooled to 0 °C. The Et2O
was decanted from the oil, which had settled on the flask. The
oil was washed with Et2O, and the Et2O was decanted again.
To the oil was added Et2O again, and the mixture was
sonicated. The oil gradually crystallized, and the solid was
Sample prepared by dissolving crude material into 2 mL of
mobile phase.
tR of major peak ) 134 min.
2-{4-[2-[(3-Ca r boxyp r op a n oyl)a m in o]-3-oxo-3-(p en tyl-
a m in o)p r op yl]-2,3,5,6-tetr a flu or op h en oxy}m a lon ic a cid
(21) was prepared from N-Boc-L-2,3,5,6-tetrafluorotyrosine33
by procedures analogous to those described for the transforma-
tion of 2 to 14 (Scheme 3). 21 was obtained as an off-white
1
solid: mp 122 °C dec; [R]25 ) -6°(c 0.54, ethanol); H NMR
D
(300 MHz, DMSO-d6) δ 8.15 (br d, J ) 8 Hz, 1 H), 7.91 (br t,
1 H), 5.32 (s, 1 H), 4.47 (q, J ) 8 Hz, 1 H), 3.07-2.97 (m, 2 H),
2.92-2.82 (m, 2 H), 2.33-2.30 (m, 4 H), 1.27-1.07 (m, 6 H),
0.82 (t, J ) 7 Hz, 3 H); MS (FAB) m/z 525 (MH+), 525, 177,

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 611
133, 101, 88, 86, 74, 55, 43, 23; HRMS (FAB) calcd for
Dieth yl 2-(4-{(2S)-3-(Ben zyloxy)-2-[(4-m eth oxy-4-oxo-
bu ta n oyl)a m in o]-3-oxop r op yl}p h en oxy)m a lon a te (27b).
To a mixture of 26b (2.64 g, 6.85 mmol) and K2CO3 (1.9 mmol,
13.7 mmol) in acetone (20 mL) was added diethyl chloroma-
lonate (2.2 mL, 13.7 mmol). The mixture was stirred vigorously
for 18 h. The mixture was partitioned between EtOAc and
H2O. The organic phase was washed with sat. NaHCO3 and
sat. NaCl. After drying (MgSO4), the solvent was removed
under reduced pressure. The residue was purified by flash
chromatography (50% EtOAc/hexane) to provide 2.9 g of 27b
as a colorless oil (contaminated with approximately 10% of the
corresponding R-chloromalonate): 1H NMR (CDCl3) δ 7.37 (m,
3 H), 7.29 (m, 2 H), 6.90 (d, 2 H), 6.80 (d, 2 H), 6.06 (d, 1 H),
5.12 (m, 3 H), 4.86 (q, 1 H), 4.31 (q, 4 H), 3.67 (s, 3 H), 3.05
(m, 2 H), 2.62 (m, 2 H), 2.48 (t, 2 H), 1.30 (t, 6 H).
(2S)-3-{4-[2-Eth oxy-1-(eth oxyca r bon yl)-2-oxoeth oxy]-
p h en yl}-2-[(4-m et h oxy-4-oxob u t a n oyl)a m in o]p r op a n o-
ic Acid (28b). A Parr flask was charged with 27b (150 mg,
0.28 mmol), 10% Pd/C (25 mg), and abs. EtOH (25 mL), and
the mixture was hydrogenated (35 psi) for 45 min. The mixture
was filtered through Celite and concentrated to provide 110
mg (87%) of 28b as a colorless oil: 1H NMR (CDCl3) δ 7.11 (d,
2 H), 6.88 (d, 2 H), 6.23 (d, 1 H), 5.17 (s, 1 H), 4.79 (q, 1 H),
4.30 (q, 4 H), 3.67 (s, 3 H), 3.15 (ab q, 1 H), 3.06 (ab q, 1 H),
2.63 (t, 2 H), 2.28 (t, 2 H), 1.30 (t, 6 H).
Gen er a l P r oced u r e for th e P r ep a r a tion of 30 fr om 28b
(Sch em e 4). To a mixture of 28b (1 equiv) in CH2Cl2 (0.2 M)
at 0 °C was added EDC (1 equiv) followed by the requisite
amine. The reaction was warmed to room temperature and
stirred for 18 h. The mixture was diluted with EtOAc and
washed with 1 M HCl, sat. NaHCO3, and sat. NaCl. The
organic phase was dried (MgSO4) and concentrated under
reduced pressure to give the crude ester 29b. The residue was
dissolved in THF (3 mL), and a solution of LiOH·H2O (6-8
equiv) in H2O (1 mL) was added. The mixture was stirred for
2-4 h. The mixture was acidified with 1M HCl and extracted
with EtOAc (3×). The combined organic phase was washed
with sat. NaCl and dried (MgSO4). The solvent was removed
in vacuo to provide 30.
Diben zyl 2-{4-[(2S)-2-({(2S)-4-(Ben zyloxy)-2-[(ter t-bu t-
oxyca r b on yl)a m in o]-4-oxob u t a n oyl}a m in o)-3-oxo-3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon a te (31). To a stir-
ring solution of 12a (0.25 g, 0.44 mmol) and triethylamine
(0.044 g, 0.44 mmol) was added Boc-Asp(OBn)OSu (0.185 g,
0.44 mmol) at 0 °C. The resulting solution was stirred for 16
h, and the mixture was allowed to warm to ambient temper-
ature. The resulting solution was diluted with CH2Cl2 (50 mL)
and washed with 10% aqueous HCl. The organic layer was
dried over MgSO4 and solvent removed to afford 0.33 g (87%)
of 31 as a white solid: 1H NMR (CDCl3) δ 0.84 (t, 3 H), 1.15-
1.43 (m, 15 H), 2.76 (m, 1 H), 2.93 (m, 2 H), 3.09 (m, 3 H),
4.41 (m, 1 H), 4.48 (m, 1 H), 5.10 (s, 2 H), 5.23 (s, 4 H), 5.29 (s,
1 H), 5.44 (d, 1 H), 5.91 (m, 1 H), 6.89 (d, 1 H), 6.85 (d, 2 H),
7.10 (d, 2 H), 7.30 (m, 15 H).
C
21H24F4N2O9 + H 525.1496, found 525.1495.
Ben zyl 4-{[(1S)-2-(ter t-Bu toxy)-1-(4-h yd r oxyben zyl)-2-
oxoeth yl]a m in o}-4-oxobu ta n oa te (26a ). To a stirring solu-
tion of H-Tyr-OBut (25a ) (3.0 g, 12.64 mmol) in CH2Cl2 (150
mL) at 0 °C was added EDC (2.42 g, 12.64 mmol) and
monobenzyl succinate (2.62 g, 12.64 mmol). The mixture was
stirred for 16 h, the solution being allowed to warm to ambient
temperature. The resulting solution was washed with 10%
HCl/H2O (150 mL), and the organic phase was dried over Na2-
SO4 and evaporated in vacuo. The residue was purified via
flash column chromatography (2:1 hexane/EtOAc) to afford
5.06 g (94%): 1H NMR (CDCl3) δ 1.41 (s, 9 H), 2.50 (m, 2 H),
2.67 (m, 2 H), 2.99 (m, 2 H), 4.68 (m, 1 H), 5.11 (s, 2 H), 5.54
(brs, 1 H), 6.12 (d, 1 H), 6.71 (d, 2 H), 6.98 (d, 2 H), 7.33
(m, 5 H).
Diben zyl 2-{4-[(2S)-2-{[4-(Ben zyloxy)-4-oxobu ta n oyl]-
a m in o}-3-(ter t-bu toxy)-3-oxop r op yl]p h en oxy}m a lon a te
(27a ). To a stirring solution of 26a (3.55 g, 8.31 mmol) in
acetone (175 mL) at ambient temperature was added K2CO3
(2.29 g, 16.62 mmol). Dibenzyl bromomalonate (3.31 g, 9.14
mmol) was added, and the mixture was stirred at ambient
temperature overnight. The solvent was removed in vacuo, and
the residue was suspended between EtOAc/H2O (100 mL each).
The layers were shaken, and the organic layer was separated
and dried over Na2SO4, and the solvent was removed. The
residue was purified via flash chromatography to afford 1.72
g (29%) title compound as a yellow oil: 1H NMR (CDCl3) δ
1.39 (s, 9 H), 2.49 (m, 2 H), 2.68 (m, 2 H), 3.00 (d, 2 H), 4.66
(m, 1 H), 5.11 (s, 2 H), 5.23 (s, 4 H), 5.24 (s, 1 H), 6.05 (d, 1 H),
6.82 (d, 2 H), 7.03 (d, 2 H), 7.33 (m, 15 H).
(2S )-3-(4-{2-(Be n zyloxy)-1-[(b e n zyloxy)ca r b on yl]-2-
oxoe t h oxy}p h e n yl)-2-{[4-(b e n zyloxy)-4-oxob u t a n oyl]-
a m in o}p r op a n oic Acid (28a ). To a stirring solution of 27a
(1.56 g, 2.20 mmol) in CH2Cl2 (40 mL) was added trifluoroacetic
acid (100 mL). The resulting solution was stirred for 2 h and
solvent removed in vacuo to afford 1.42 g (quant) of 28a as a
slightly pink oil: 1H NMR (CDCl3) δ 2.52 (m, 2 H), 2.67 (t, 2
H), 3.07 (ddd, 2 H), 4.81 (q, 1 H), 5.10 (s, 2 H), 5.20 (s, 4 H),
5.25 (s, 1 H), 6.43 (d, 1 H), 6.83 (d, 2 H), 7.40 (d, 2 H), 7.31 (M,
15 H), 7.80 (brs, 1 H).
Gen er a l P r oced u r e for Cou p lin g of Am in es w ith 28a
To Affor d Am id es 29a . To a stirring solution of 28a in
CH2Cl2 (0.035 M) at 0 °C was added EDC (1 equiv), followed
by the requisite amine. The mixture was stirred for 16 h,
allowing the solution to warm to ambient temperature. The
mixture was diluted with CH2Cl2 (50 mL) and then washed
with 10% HCl/H2O and then saturated NaHCO3. The solvent
was dried over Na2SO4 and removed in vacuo. Purification by
SiO2 flash column chromatography (eluant 1:1 EtOAc/hexane)
afforded the desired amide.
Gen er a l P r oced u r e for H yd r ogen a t ion of Ben zyl
Ester s 29a to Acid s 30. To a stirring solution of the requisite
ester in MeOH (0.03 M) was added 10% Pd-C (10% w/w). The
resulting mixture was hydrogenated at atmospheric pressure
for 3 h and filtered through Celite. The solvent was removed
in vacuo to afford the desired triacids.
2-{4-[(2S)-2-({(2S)-2-[(ter t-Bu t oxyca r b on yl)a m in o]-3-
ca r boxyp r op a n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic Acid (32). To a solution of 31 (0.317 g,
0.38 mmol) in MeOH (15 mL) at ambient temperature was
added 10% Pd-C (50 mg), and the resulting mixture was
hydrogenated at atmospheric pressure for 2 h. The mixture
was filtered through Celite and the solvent removed to afford
0.208 g (97%) of 31 as a white solid: 1H NMR (DMSO) δ 0.82
(t, 3 H), 1.12-1.40 (m, 15 H), 2.30-2.52 (m, 2 H), 2.70-3.06
(m, 4 H), 4.16 (m, 1 H), 4.32 (m, 1 H), 5.20 (s, 1 H), 6.76 (d, 2
H), 7.60 (m, 2 H), 7.12 (d, 1 H), 7.69 (d, 1 H), 7.78 (t, 1 H)
(3-CO2H absent); MS (FAB) m/z (rel intensity) 568 (MH+, 9),
512 (31), 468 (23), 88 (99), 88 (25), 86 (20), 57 (95), 43 (21), 41
(28), 29 (26), 23 (27). Anal. (C26H37N3O11·1.48H2O) C, H, N.
4-{[(1S)-3-(Ben zyloxy)-1-({[(1S)-1-(4-{2-(b en zyloxy)-1-
[(b e n zyloxy)ca r b on yl]-2-oxoe t h oxy}b e n zyl)-2-oxo-2-
(pen tylam in o)eth yl]am in o}car bon yl)-3-oxopr opyl]am in o}-
4-oxobu ta n oic Acid (33). To a solution of 31 (0.263 g, 0.31
mmol) in HOAc (5 mL) was added 1.5 M HCl/HOAc (5 mL),
and the resulting solution was allowed to stand for 2 h. The
Meth yl 4-{[(1S)-2-(Ben zyloxy)-1-(4-h yd r oxyben zyl)-2-
oxoet h yl]a m in o}-4-oxob u t a n oa t e (26b ). To a mixture of
L-tyrosine benzyl ester p-toluenesulfonate salt (25b)(5.0 g, 11.3
mmol) and triethylamine in CH2Cl2 (25 mL) at 0 °C were added
EDC (2.2 g, 11.3 mmol) and monomethyl succinate (1.5 g, 11.3
mmol). The mixture was warmed to room temperature and
stirred overnight. The mixture was diluted with EtOAc (150
mL) and washed with 1 M HCl (50 mL), sat. NaHCO3 (50 mL),
and sat. NaCl (50 mL). The organic phase was dried (MgSO4),
and the solvent was removed under reduced pressure. The
residue was purified by flash chromatography (SiO2, 60%
EtOAc/hexane) to provide 3.4 g (78%) of 26b as a colorless oil
that slowly solidified to a white solid: 1H NMR (CDCl3) δ 7.33
(m, 5 H), 6.84 (d, 2 H), 6.65 (d, 2 H), 6.15 (d, 1 H), 5.62 (br s,
1 H), 5.14 (q, 2 H), 4.87 (m, 1 H), 3.67 (s, 3 H), 3.01 (m, 2 H),
2.64 (m, 2 H), 2.47 (m, 2 H).

612 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
solvent was removed in vacuo to afford 0.24 g (quant) of the
amine hydrochloride as a white solid. To a stirring solution of
this crude amine (0.10 g, 0.13 mmol) and triethylamine (0.028
g, 0.28 mmol) in CH2Cl2 (8 mL) at 0 °C was added succinic
anhydride (0.015 g, 0.13 mmol). The resulting solution was
stirred for 16 h, the solution being allowed to warm to ambient
temperature. The mixture was diluted with CH2Cl2 (50 mL)
and washed with 10% aqueous HCl. The organic layer was
dried over MgSO4 and concentrated to afford 0.076 g (70%) of
as described for 38, affording 37: 1H NMR (DMSO-d6) δ 8.00
(d, 1 H), 7.88 (t, 1 H), 7.66 (m, 5 H), 7.53 (t, 2 H), 7.12 (d, 2 H),
7.00 (d, 1 H), 6.80 (d, 2 H), 5.23 (s, 1 H), 4.40 (m, 1 H), 4.30
(m, 1 H), 2.70-3.05 (m, 6 H), 1.10-1.30 (m, 15 H), 0.80 (t, 3
H); MS (FAB) m/z (rel intensity) 704 (MH+, 6), 648 (30), 238
(23), 224 (49), 194 (30), 136 (20), 105 (33), 88 (99), 57 (88), 43
(24), 41 (22); HRMS (FAB) calcd for C38H45N3O10 + H 704.3183,
found 704.3171. Anal. (C38H45N3O10·0.80H2O) C, H, N.
2-{4-[(2S )-2-({(2S )-3-(4-B e n zo y lp h e n y l)-2-[(3-c a r -
b o x y p r o p a n o y l)a m i n o ]p r o p a n o y l}a m i n o )-3-o x o -3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon ic Acid (38). Com-
pound 36 (0.34 mmol) was dissolved in a 1 M solution of HCl
in acetic acid (4 mL) and stirred at room temperature for 3 h.
The solvent was removed under reduced pressure, and the
residue was dissolved in a mixture of triethylamine (0.75
mmol) in CH2Cl2 (1.5 mL). The mixture was cooled to 0 °C,
and succinic anhydride (0.34 mmol) was added. The mixture
was warmed to room temperature and stirred overnight. The
mixture was partitioned between EtOAc and 1 M HCl, and
the organic phase was washed with sat. NaCl and dried
(MgSO4). After the solvent was removed, the residue was
dissolved in THF (3 mL), and a solution of LiOH·H2O (1-2
mmol) in H2O (1 mL) was added. The mixture was stirred for
2-5 h. The mixture was neutralized with 1 M HCl and
extracted with EtOAc (2×). The combined organic phases were
washed with sat. NaCl and dried (MgSO4). The solvent was
removed in vacuo to provide 38 (169 mg, 70%) as an off-white
solid: 1H NMR (DMSO) δ 8.12 (d, 1 H), 8.05 (d, 1 H), 7.75 (t,
1 H), 7.70-7.75 (m, 7 H), 7.35 (d, 2 H), 7.11 (d, 2 H), 6.81 (d,
2 H), 5.25 (s, 1 H), 4.51 (m, 1 H), 4.35 (m, 1 H), 2.70-3.05 (m,
6 H), 2.32 (m, 4 H), 1.10-1.35 (m, 6 H), 0.80 (t, 3 H); MS (FAB)
m/z (rel intensity) 704 (MH+, 88), 705 (39), 704 (88), 353 (30),
238 (36), 224 (99), 194 (25), 136 (23), 107 (14), 105 (29), 88
(40); HRMS (FAB) calcd for C37H41N3O11 + H 704.2819, found
704.2804. Anal. (C37H41N3O11·0.63H2O) C, H, N.
Met h yl 4-{[(1S)-1-(4-h yd r oxyb en zyl)-2-oxo-2-(p en t yl-
a m in o)eth yl]a m in o}-4-oxobu ta n oa te (39) was prepared as
described for 6 using (mono)methyl succinate: 1H NMR
(CDCl3) 7.04 (d, J ) 8 Hz, 2 H), 6.74 (d, J ) 8 Hz, 2 H), 6.40
(bs, 1 H), 6.32 (d, J ) 8 Hz, 1 H), 6.04 (bt, J ) 8 Hz, 1 H), 4.55
(q, J ) 7 Hz, 1 H), 3.66 (s, 3 H), 3.13 (q, J ) 7 Hz, 2 H), 3.03,
2.92 (ABqd, J ) 7, 14 Hz, 2 H), 2.5-2.8 (m, 2 H), 2.45 (m, 2
H), 1.1-1.4 (m, 6 H), 0.86 (t, J ) 7 Hz, 3 H).
4-{[(1S)-1-{4-[(2-Ca r b oxya cet yl)oxy]b en zyl}-2-oxo-2-
(p en tyla m in o)eth yl]a m in o}-4-oxobu ta n oic Acid (40). To
a mixture of 6 (100 mg, 0.227 mmol) and benzyl malonyl
chloride (72 mg, 0.34 mmol) in methylene chloride (1 mL) was
added pyridine (40 µL). The mixture immediately went into
solution. After 1 h, the solution was diluted with ethyl acetate
and washed successively with dilute HCl, water, and sat.
sodium bicarbonate. Drying of the organic phase and concen-
tration left a yellow viscous oil (158 mg). NMR analysis showed
some starting material left, so the reaction was repeated for
19 h. The two crude reaction products were combined and flash
chromatographed (30 g, 80% ethyl acetate/hexane), providing
the desired ester (90 mg, 32%) as the highest Rf material: 1H
NMR (CDCl3) 7.35 (m, 5H), 7.20 (d, 2H, J ) 8 Hz), 6.98 (d,
2H, J ) 8 Hz), 6.12 (d, 1H, J ) 8 Hz), 5.88 (bt, 1H, J ) 6 Hz),
5.23 (s, 2H), 5.11 (s, 2H), 4.57 (m, 1H), 3.64 (s, 2H), 3.12 (m,
3H), 2.98 (dd, 1H, J ) 8, 14 Hz), 2.6-2.9 (m, 2H), 2.45 (m,
2H), 1.1-1.4 (m, 6H), 0.86 (t, 3H, J ) 7 Hz).
1
33 as a white solid: H NMR (CDCl3) δ 0.85 (t, 3 H), 1.23 (m,
4 H), 1.40 (m, 2 H), 2.37 (m, 2 H), 2.68 (m, 2 H), 3.14 (m, 6 H),
4.57 (m, 1 H), 4.72 (m, 1 H), 5.01 (dd, 2 H), 5.16 (s, 4 H), 5.21
(s, 1 H), 6.36 (t, 1 H), 6.80 (m, 2 H), 7.05 (d, 2 H), 7.25 (m, 17
H) (CO2H absent).
2-{4-[(2S)-2-({(2S)-3-Ca r boxy-2-[(3-ca r boxyp r op a n oyl)-
a m in o]p r op a n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic Acid (34). To a stirring solution of 33 (0.07
g, 0.08 mmol) in MeOH (5 mL) was added 10% Pd-C (10 mg).
The resulting mixture was hydrogenated at atmospheric
pressure for 2 h and filtered through Celite. The solvent was
removed to afford 0.044 g (94%) of 34 as a white amorphous
solid: 1H NMR (DMSO) δ 0.82 (t, 3 H), 1.20 (m, 6 H), 2.33 (m,
3 H), 2.43 (m, 3 H), 2.72 (m, 1 H), 2.96 (m, 3 H), 4.27 (m, 1 H),
4.42 (m, 1 H), 5.2 (s, 1 H), 6.74 (d, 2 H), 7.06 (d, 2 H), 7.60 (t,
1 H), 7.70 (d, 1 H), 8.30 (d, 1 H) (4-CO2H absent); MS (FAB)
m/z (rel intensity) 568 (MH+, 99), 582 (26), 569 (32), 568 (99),
238 (40), 177 (42), 102 (37), 88 (56), 88 (53), 39 (24), 23 (26).
Anal. (C25H33N3O12·1.1H2O) C, H, N.
2-{4-[(2S)-2-{[(2S)-3-Ca r b oxy-2-(h exa n oyla m in o)p r o-
p a n oyl]a m in o}-3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}-
m a lon ic Acid (35). To a stirring solution of the amine
hydrochloride derived from deprotection of 31 (as described
for preparation of 33) (0.25 g, 0.32 mmol) in CH2Cl2 (8 mL) at
0 °C was added hexanoyl chloride (0.043 g, 0.32 mmol). The
resulting solution was stirred for 16 h, the mixture being
allowed to warm to ambient temperature. The solution was
diluted with CH2Cl2 (20 mL) and washed with 10% HCl/H2O
(3 × 50 mL). The organic layer was dried over Na2SO4 and
concentrated to afford 0.164 g (61%) of the amide as a white
solid. To a stirring solution of crude amide (0.175 g, 0.22 mmol)
in MeOH (15 mL) was added 10% Pd-C (25 mg). The mixture
was hydrogenated at atmospheric pressure for 3 h and filtered
through Celite. The solvent was removed to afford 0.113 g
1
(87%) 35 as a white solid: H NMR (DMSO) δ 0.82 (m, 6 H),
1.22 (m, 10 H), 1.44 (m, 2 H), 2.04 (t, 2 H), 2.38 (m, 1 H), 2.62
(m, 1 H), 2.63-3.10 (m, 4 H), 4.32 (m, 1 H), 4.51 (m, 1 H),
5.19 (s, 1 H), 6.75 (d, 2 H), 7.04 (d, 2 H), 7.74 (m, 2 H), 8.10 (d,
1 H) (3-CO2H absent); MS (FAB) m/z (rel intensity) 566 (MH+,
37), 588 (24), 566 (37), 177 (38), 99 (26), 88 (56), 88 (88), 71
(29), 43 (99), 39 (54), 23 (89). Anal. (C27H39N3O10·0.78H2O) C,
H, N.
Dieth yl 2-{4-[(2S)-2-({(2S)-3-(4-Ben zoylp h en yl)-2-[(ter t-
b u t o x y c a r b o n y l)a m in o ]p r o p a n o y l}a m in o )-3-o x o -3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon a te (36). To a mix-
ture of L-Boc-Bpa-OH (0.93 g, 2.5 mmol) in CH2Cl2 (5 mL) at
0 °C was added EDC (0.48 g, 2.5 mmol) and HOBT (0.34 g,
2.5 mmol). After stirring for a few minutes, 12b (1.12 g, 2.5
mmol) and triethylamine (0.39 mL, 2.8 mmol) were added. The
mixture was warmed to room temperature and stirred over-
night. The mixture was partitioned between 1 M HCl and
EtOAc. The organic phase was washed with sat. NaHCO3 and
sat. NaCl and dried (MgSO4). The solvent was removed under
reduced pressure, and the residue was purified by flash
chromatography (85 g of SiO2, 25% EtOAc/hexane) to provide
1.0 g (58%) of 36 as a white solid: 1H NMR (DMSO-d6) δ 8.00
(d, 1 H), 7.91 (t, 1 H), 7.60-7.70 (m, 5 H), 7.54 (t, 2 H), 7.13
(d, 2 H), 6.97 (d, 1 H), 6.83 (d, 2 H), 5.58 (s, 1 H), 4.40 (m, 1
H), 4.16 (m, 5 H), 2.80-3.00 (m, 4 H), 2.75 (m, 2 H), 1.28 (m,
10 H), 1.68 (m, 11 H), 0.81 (t, 3 H).
A mixture of the ester from above (84 mg, 0.14 mmol) and
10% Pd/C (20 mg) in methanol (7 mL) was hydrogenated at 1
atm for 1 h. Concentration in vacuo left a colorless glass (58
mg, 95%). NMR analysis indicated the desired product con-
taminated with 5-10% of the corresponding free phenol: 1H
NMR (DMSO) 8.09 (d, 1H, J ) 7 Hz), 7.81 (bt, 1H, J ) 6 Hz),
7.23 (d, 2H, J ) 8 Hz), 6.98 (d, 2H, J ) 8 Hz), 4.4 (m, 1H),
3.61 (s, 2H), 2.95 (m, 3H), 2.7 (m, 1H), 2.3 (m, 4H), 1.1-1.4
(m, 6H), 0.82 (t, 3H, J ) 7 Hz); HRMS (FAB) calcd for
2-{4-[(2S )-2-({(2S )-3-(4-B e n z o y lp h e n y l)-2-[(t er t -
b u t o x y c a r b o n y l)a m in o ]p r o p a n o y l}a m in o )-3-o x o -3-
(p en t yla m in o)p r op yl]p h en oxy}m a lon ic a cid (37) was
prepared by direct LiOH saponification of 36 with isolation
C
21H28N2O8 + H 437.1924, found 437.1924.
4-{[(1S)-1-[4-(Car boxym eth oxy)ben zyl]-2-oxo-2-(pen tyl-
a m in o)eth yl]a m in o}-4-oxobu ta n oic Acid (41). A mixture

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 613
of 6 (300 mg, 0.681 mmol), potassium bicarbonate (136 mg,
1.36 mmol), and benzyl bromoacetate (216 µL, 1.36 mmol) in
acetone (5 mL) was stirred at 50-55 °C for 3 days. TLC
analysis showed some starting material left, so another 1 equiv
of bromide was added, and the mixture was stirred a further
24 h. Aqueous workup (ethyl acetate/water/brine) gave a solid
and oil. Flash chromatography (60 g silica, 1/1 ethyl acetate:
methylene chloride) gave a colorless oil (Rf ) 0.45, 285 mg)
that was impure product. This material was left standing in
methylene chloride:hexane at 0 °C overnight, producing some
crystals in an oil. After sonication, all of the material became
a white solid. Filtration gave 166 mg of the ether diester (41%)
after washing with hexane and drying (mp 102-103 °C): 1H
NMR (CDCl3) 7.34 (m, 5H), 7.12 (d, 2H, J ) 9 Hz), 6.82 (d,
2H, J ) 9 Hz), 6.10 (d, 1H, J ) 8 Hz), 5.81 (bt, 1H, J ) 7 Hz),
5.23 (s, 2H), 5.12 and 5.08 (Abq, 2H, J ) 12 Hz), 4.63 (s, 2H),
4.52 (m, 1H), 3.1 (m, 2H), 2.90 (dd, 1H, J ) 8, 14 Hz), 2.6-
2.85 (m, 2H), 2.45 (m, 2H), 1.1-1.4 (m, 6H), 0.86 (t, 3H, J )
7 Hz).
Dim eth yl (Z)-2-{4-[(2S)-2-[(4-Meth oxy-4-oxobu ta n oyl)-
am in o]-3-oxo-3-(pen tylam in o)pr opyl]ph en oxy}-2-bu ten e-
d ioa te (44). To a mixture of 39 (0.37 g, 1.0 mmol) and
triethylamine (0.17 mmol, 1.2 mmol) in THF (5 mL) was added
dimethyl acetylenedicarboxylate (0.25 mL, 2.0 mmol), and the
mixture was heated at 50 °C overnight. The mixture was
diluted with Et2O and washed with 1 M HCl and sat. NaCl.
The organic phase was dried (Na2SO4) and concentrated. The
residue was purified by flash chromatography (SiO2, 90%
EtOAc/hexane) to yield 0.41 g (79%) of 44 as a 1:1 mixture of
isomers: 1H NMR (CDCl3) δ (all peaks overlap except aromatic
and olefin) nonoverlapping peaks, 7.26 (d, 2 H), 7.15 (d, 2 H),
7.04 (d, 2 H), 6.89 (d, 2 H) 6.58 (s,1 H, fumarate), 5.12 (s, 1 H,
maleate), 3.91 (s, 3 H, methyl ester); overlapping peaks, 6.16
(t, 1 H, NH), 5.94 (m, 1 H, NH), 4.56 (m, 1 H), 3.73, 3.70, 3.67
(s, methyl ester), 2.92-3.20 (m, 4 H), 2.55-3.80 (m, 2 H), 2.43
(m, 2 H), 1.38 (m, 2 H), 1.25 (m, 4 H), 0.87 (t, 3 H).
(Z)-2-{4-[(2S)-2-[(4-H yd r oxy-4-oxob u t a n oyl)a m in o]-3-
oxo-3-(pen tylam in o)pr opyl]ph en oxy}-2-bu ten edioic Acid
(45). To a mixture of 44 (100 mg, 0.20 mmol) in MeOH (5 mL)
was added a solution of LiOH·H2O (50 mg, 1.2 mmol) in H2O
(1.5 mL), and the mixture was stirred at room temperature
overnight. The reaction mixture was concentrated in vacuo,
and the residue was dissolved in H2O. After cooling to 0 °C, 1
M HCl was added until pH ) 1. The solid that slowly
precipitated over several hours at 0 °C was collected and dried
to provide 30 mg (32%) of 45 (6:1 mixture of isomers) as a
slightly yellow solid: 1H NMR (MeOH) δ 7.18 (d, 2 H, major
isomer), 6.86 (d, 2 H, major isomer), 6.55 (s, 1 H, major isomer),
5.10 (s, 1 H, minor isomer), 4.49 (m, 1 H), 3.10 (m, 3 H), 2.87
(m, 1 H), 2.39-2.54 (m, 4 H), 1.27-1.45 (m, 6 H), 0.90 (t,
3 H); the major isomer was assigned as E on the basis of
the relative chemical shifts of olefinic protons; HRMS (FAB)
calcd for C22H28N2O9 + H 465.1873, found 465.1856. Anal.
(C22H28N2O9·1.28H2O) C, H, N.
2-{4-[(2S )-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-oxo-3-
(p en tyla m in o)p r op yl]p h en oxy}su ccin ic Acid (46). To a
suspension of 6 (50 mg, 0.11 mmol) and triethylamine (18 mL,
0.13 mmol) in THF (0.3 mL) was added a solution of dibenzyl
acetylenedicarboxylate (35 mg, 0.12 mmol) in THF (0.2 mL).
The reaction mixture was heated at 50 °C for 20 h. The
mixture was diluted with Et2O and washed with 1 M HCl and
sat. NaCl. The organic phase was dried (Na2SO4), and the
solvent was removed in vacuo. The residue was purified by
flash chromatography (9 g SiO2, 60% EtOAc/hexane) to provide
48 mg (59%) of 43 as a 1:1 mixture of isomers: 1H NMR
(CDCl3) δ (all peaks overlap except aromatic and olefin)
nonoverlapping, 7.21 (d, 2 H), 7.10 (d, 2 H), 7.02 (d, 2 H), 6.86
(d, 2 H), 6.62 (s, 1 H, fumarate), 5.30 (s, 1 H, maleate);
overlapping, 7.30-7.40 (m, 5 H, Ph benzyl ester), 6.11 (m, 1
H, NH), 5.90 (m, 1 H, NH), 5.06-5.21 (complex, CH2 benzyl
esters), 4.55 (m, 1 H), 3.10 (m, 3 H), 2.90-3.00 (dd, 1 H), 2.60-
2.85 (m, 2 H), 2.43 (m, 2 H), 1.10-1.40 (m, 6 H), 0.84 (m, 3
H); MS (ESI+) for C43H46N2O9 m/z 735 (M +H)+, 757 (M +
Na).
A mixture of 43 (48 mg) and 10% Pd/C (5 mg) in MeOH (2
mL) was stirred under a hydrogen atmosphere (balloon) for 1
h. The mixture was filtered through Celite and concentrated
to provide 27 mg (90%) of 46 as a glass: 1H NMR (DMSO) 8.02
(d, 1 H), 7.78 (m, 1 H), 7.08 (d, 2 H), 6.76 (d, 2 H), 4.92 (m, 1
H), 4.32 (m, 1 H), 2.6-3.0 (m, 6 H), 2.25-2.35 (m, 4 H), 1.1-
1.4 (m, 6 H), 0.83 (t, 3 H); MS (FAB) m/z (rel intensity) 467
(MH+, 71), 489 (22), 468 (17), 467 (71), 349 (11), 252 (38), 136
(13), 107 (11), 88 (99), 86 (17), 43 (20); HRMS (FAB) calcd for
A mixture of the diester from above (100 mg, 0.170 mmol)
and 10% Pd/C (20 mg) in methanol (10 mL) was hydrogenated
at 1 atm for 1.5 h. The mixture was filtered through Celite
and concentrated in vacuo to a colorless glass (69 mg, ap-
proximately 100%). Sonication in methylene chloride and
evaporation of the solvent left a white powdery solid (mp 106-
109 °C): 1H NMR (MeOD) 7.81 (t, 1H, J ) 6 Hz), 7.15 (d, 2H,
J ) 9 Hz), 6.84 (d, 2H, J ) 9 Hz), 4.60 (s, 2H), 4.49 (dd, 1H,
J ) 6.3, 8.5 Hz), 3.1 (m, 3H), 2.81 (dd, 1H, J ) 8.6, 14 Hz),
2.3-2.7 (m, 4H), 1.1-1.4 (m, 6H), 0.88 (t, 3H, J ) 7 Hz); 13C
NMR (MeOD) 175.0, 173.1, 172.0, 171.4, 156.9, 130.1, 129.9,
114.2, 64.6, 55.1, 39.2, 39.1, 36.7, 30.0, 28.7, 28.5, 22.0, 12.9;
MS (ESI-) for C20H28N2O7 m/z 407.0 (M - H)-; MS (FAB) m/z
(rel intensity) 409 (MH+, 99), 432 (17), 431 (40), 410 (45), 409
(99), 291 (16), 194 (73), 89 (22), 88 (97), 86 (16), 43 (20); HRMS
(FAB) calcd for C20H28N2O7 + H 409.1974, found 409.1985.
Anal. (C20H28N2O7·0.3H2O) C, H, N.
4-{[(1S)-1-{4-[(Meth ylsu lfon yl)oxy]ben zyl}-2-oxo-2-(pen -
tyla m in o)eth yl]a m in o}-4-oxobu ta n oic Acid (42). A mag-
netically stirred suspension of 6 (320 mg, 0.73 mmol) in
dichloromethane (5 mL) was cooled to 0 °C and treated
dropwise with triethylamine (0.5 mL) and mesyl chloride (70
uL, 1.2 equiv) under N2 atmosphere. The reaction mixture was
allowed to warm to ambient temperature and after 1 h. TLC
showed complete conversion. Dichloromethane (30 mL) was
added and the organic layer was washed with aqueous HCl
(10%, 25 mL) and dried over MgSO4. Filtration and removal
of the solvent in vacuo gave 0.40 g of an off-white solid.
Recrystallization from acetonitrile gave a first crop of mesylate
ester (0.24 g crystalline white solid). A second crop gave an
additional 50 mg. The total yield amounted to 0.29 g (77%):
1
mp 167.1-168.3 °C; H NMR (CDCl3) δ 0.86 (t, J ) 7.1, 3H),
1.15-1.30 (m, 4H), 1.35-1.43 (m, 2H), 2.43-2.50 (m, 2H),
2.61-2.79 (m, 2H), 3.07-3.17 (m, 4H), 3.12 (s, 3H), 4.65 (dt,
J 1 ) 8.1, J 2 ) 6.9, 1H), 5.10 (s, 2H), 6.23 (t, J ) 5.6, 1H), 6.38
(d, J ) 8.2, 1H), 7.19 (d, J ) 8.7, 2H), 7.25 (d, J ) 8.7, 2H),
7.30-7.37 (m, 5H).
To a stirred solution of the above ester (233 mg, 449 µmol)
in THF (6 mL) were added aqueous LiOH (2.5 M, 400 µL, 2.2
equiv) and methanol (1.5 mL). After 30 min the reaction
mixture was taken up in sat. aq NaHCO3 (30 mL) and washed
with diethyl ether (25 mL). The aqueous layer was then
acidified until pH 3 with 10% HCl and extracted with ethyl
acetate (3 × 20 mL). The combined organic layers were dried
(Na2SO4) and evaporated in vacuo, giving 194 mg of a white
solid that was recrystallized from acetone. This afforded 128
mg of 42 (67%) as white yellow crystals: mp 165.0-166.2 °C;
1H NMR (CD3OD) δ 0.91 (t, J ) 7.0, 3H), 1.21-1.37 (m, 4H),
1.41-1.48 (m, 2H), 2.37-2.64 (m, 4H), 2.92 (dd, J 1,2 ) 8.8, 1H),
3.10-3.22 (m, 3H), 3.20 (s, 3H), 4.58 (dd, J 1 ) 8.7, J 2 ) 8.6,
1H), 7.25 (d, J ) 8.6, 2H), 7.35 (d, J ) 8.6, 2H); 13C NMR (CD3-
OD) δ 14.78, 23.79, 30.36, 30.52, 31.75, 37.82, 38.62, 40.88,
41.01, 56.50, 123.59, 132.28, 138.61, 150.20, 173.50, 174.97,
176.75; MS (ionspray, [M - H]-) m/z 427.2. Anal. (C19H28N2O7S)
C, H, N.
C
22H30N2O9 + H 467.2029, found 467.2040.
ter t-Bu tyl (1S)-1-(4-F or m ylben zyl)-2-oxo-2-(p en tyla m i-
n o)eth ylca r ba m a te (47). To a stirring solution of 3 (5.0 g,
14.27 mmol) and pyridine (2.58 g, 71.38 mmol) in CH2Cl2 (50
mL) at 0 °C was added trifluoromethanesulfonic anhydride
(4.42 g, 15.70 mmol) dropwise over 15 min. After addition, the
mixture was stirred for 1 h at 0 °C and diluted with CH2Cl2
(50 mL). The organics were washed with 10% HCl/H2O (2 ×
50 mL), separated, and dried over Na2SO4. The solvent was
filtered through a pad of SiO2 (50 g) and washed with CH2Cl2

614 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
(75 mL). The solvent was removed to afford 2.54 g (37%) of
the triflate as a yellow solid: 1H NMR (CDCl3) δ 0.86 (t, 3 H),
1.18-1.50 (m, 6 H), 1.40 (s, 9 H), 3.09 (m, 4 H), 4.27 (m, 1 H),
5.07 (m, 1 H), 5.90 (t, 1 H), 7.19 (d, 2 H), 7.28 (d, 2 H).
a stirring solution of 49 (0.15 g, 0.23 mmol) in THF/MeOH
(3:1 v/v, 5 mL) at ambient temperature was added LiOH/H2O
(2.5 M, 0.52 mL, 1.38 mmol). The mixture was stirred for 3 h
and then acidified to pH ∼ 4 with 10% HCl/H2O. The aqueous
layer was extracted with EtOAc (2 × 50 mL), and the organic
layers were combined and dried over Na2SO4. The solvent was
removed to afford 0.062 g (61%) of 50 as a waxy solid: 1H NMR
(DMSO) δ 0.82 (m, 3 H), 1.13-1.17 (m, 6 H), 2.30 (m, 4 H),
2.78 (m, 1 H), 2.96 (m, 3 H), 7.20 (m, 1 H), 7.29 (m, 4 H), 7.45
(m, 1 H), 7.81 (m, 1 H), 8.10 (m, 1 H) (3-CO2H absent); MS
(FAB) m/z (rel intensity) 449 (MH+, 99), 481 (13), 450 (21),
449 (99), 363 (14), 177 (7), 133 (15), 118 (36), 88 (72), 86 (8),
43 (10).
2-{4-[(2S)-2-[(3-Car boxypr opan oyl)am in o]-3-oxo-3-(pen -
tyla m in o)p r op yl]be n zyl}m a lon ic Acid (51). To a stirring
solution of 49 (0.15 g, 0.23 mmol) in MeOH (20 mL) was added
10% Pd-C (15 mg), and the mixture was hydrogenated at
atmospheric pressure for 3 h. The solvent was filtered through
Celite and removed in vacuo to afford 0.105 g (98%) 51 as an
amorphous solid: 1H NMR (DMSO) δ 0.82 (t, 3 H), 1.15-1.30
(m, 6 H), 2.31 (m, 4 H), 2.71 (m, 1 H), 2.96 (m, 5 H), 3.09 (s, 1
H), 4.35 (m, 1 H), 7.07 (s, 4 H), 7.77 (t, 1 H), 8.06 (d, 1 H)
(3-CO2H absent); MS (FAB) m/z (rel intensity) 451 (MH+, 99),
604 (8), 452 (26), 451 (99), 407 (10), 236 (17), 192 (9), 102 (9),
88 (45), 86 (9), 43 (9). Anal. (C22H30N2O8·0.72H2O) C, H, N.
ter t-Bu t yl (1S)-1-(4-H yd r oxy-3-iod ob en zyl)-2-oxo-2-
(p en tyla m in o)eth ylca r ba m a te (53). To a stirring mixture
of 3-iodo-L-tyrosine 52 (10.0 g, 32.6 mmol) in dioxane (100 mL),
H2O (50 mL) and 1 M aqueous NaOH (50 mL) was added di-
tert-butyl dicarbonate (7.8 g, 35.8 mmol) at 0 °C. The mixture
was stirred for 2 h, and the solution, being allowed to warm
to ambient temperature, was then washed with EtOAc (2 ×
50 mL). The water layer was separated and carefully acidified
with 4 M NaHSO4·H2O in a beaker and was then extracted
with EtOAc (2 × 100 mL). The organic layer was dried (NaSO4)
and concentrated to afford 15.1 g (>100%) of the crude acid
as a yellow oil. The acid was suspended in CH2Cl2 (200 mL)
and cooled with ice to 0 °C. EDC (6.2 g, 32.6 mmol) was added
and the mixture was stirred for 10 min at 0 °C. 1-Pentylamine
(3.8 mL, 32.6 mmol) was added, and the mixture was stirred
for 16 h, the solution being allowed to warm to ambient
temperature. The mixture was washed with 10% aqueous HCl
(2 × 100 mL) and the organic layer dried (MgSO4) and
concentrated. The residue was purified by flash chromatog-
raphy (SiO2, EtOAc/n-hexane 1:1), which furnished 10.0 g
(64%) of 53 as a white solid: 1H NMR 400 MHz (CDCl3) δ 0.87
(t, 3H, J ) 7.1, 14.4), 1.21 (m, 2H),1.30 (m, 2H), 1.41 (m, 2H),
1.43 (s, 9H), 2.93 (m, 2H), 3.09-3.20 (m, 2H), 4.17 (m, 1H),
5.20 (br m, 1H), 6.00 (m, 1H), 6.85 (d, 1H, J ) 8.2), 7.05 (dd,
1H, J ) 8.2, 2.0), 7.50 (d, 1H, J ) 2.0).
Meth yl 5-[(2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-oxo-
3-(p en tyla m in o)p r op yl]-2-h yd r oxyben zoa te (54). Triethy-
lamine (0.61 mL, 4.41 mmol) was added to a stirring suspen-
sion of 53 (1.05 g, 2.20 mmol), palladium(II) acetate (14 mg,
0.066 mmol), and 1,1′-bis(diphenylphosphino)ferrocene (DPPF,
73 mg, 0.13 mmol) in DMF/MeOH 4:1 (5 mL). A carbon
monoxide atmosphere was established in the reaction vessel,
and the mixture was stirred at 70 °C for 16 h. After cooling to
ambient temperature, the mixture was extracted with EtOAc
(5 mL), and the organic layer was washed with 10% aqueous
HCl (2 × 2 mL), dried (MgSO4), and concentrated. The residue
was purified by flash chromatography (SiO2, EtOAc/n-hexane
1:2), which furnished 0.54 g (60%) of 54 as a white solid: 1H
NMR 500 MHz (CDCl3) δ 0.86 (t, 3H, J ) 7.2, 14.6), 1.17 (m,
2H), 1.25 (m, 2H), 1.36 (m, 2H), 1.41 (s, 9H), 2.97 (d, 2H, J )
7.2), 3.12-3.21 (m, 2H), 3.92 (s, 3H), 4.21 (dd, 1H, J ) 14.7,
7.2), 5.11 (br s, 1H), 5.81 (br m, 1H), 6.91 (d, 1H, J ) 8.5),
7.30 (dd, 1H, J ) 8.5, 2.1), 7.67 (d, 1H, J ) 2.1).
To the stirring mixture of crude triflate from above (0.60 g,
1.24 mmol), LiCl (0.158 g, 3.73 mmol), and vinyltributyltin
(0.591 g, 1.86 mmol) in DMF (10 mL) at ambient temperature
was added dichlorobis(triphenylphosphine)palladium(II) (0.087
g, 0.12 mmol). The mixture was heated to 90 °C and stirred
for 16 h. The resulting black mixture was cooled to ambient
temperature, poured into ice/H2O, and extracted with EtOAc
(3 × 75 mL). The organic layers were combined and dried over
Na2SO4, and the solvent was removed. The residue was
purified via SiO2 flash column chromatography (eluant 2:1
hexane/EtOAc) to afford 0.365 g (82%) of the aryl vinyl
compound as a white solid: 1H NMR (CDCl3) δ 0.84 (t, 3 H),
1.13-1.40 (m, 6 H), 1.36 (s, 9 H), 3.06 (m, 4 H), 4.23 (m, 1 H),
5.06 (brs, 1 H), 5.22 (d, 1 H), 5.68 (brs, 1 H), 5.70 (d, 1 H),
6.67 (dd, 1 H), 7.15 (d, 2 H), 7.33 (d, 2 H).
O3(g) was bubbled through a stirring solution of the vinyl
compound from above (0.30 g, 0.83 mmol) in CH2Cl2 (50 mL)
at -78 °C until the blue endpoint was observed. The reaction
mixture was capped with a septum and stirred an additional
1.5 h at -78 °C. Dimethyl sulfide (0.78 g, 0.12 mmol) was
added at -78 °C and the mixture was allowed to warm to
ambient temperature (over 1 h). The solvent was removed, and
the residue was taken up in Et2O (50 mL) and washed with
H2O (2 × 50 mL). The organic layer was dried over Na2SO4,
the solvent removed in vacuo, and the residue purified via SiO2
flash column chromatography (eluant 2:1 hexane/EtOAc) to
afford 0.172 g (57%) 47 as a white solid: 1H NMR (CDCl3) δ
0.85 (t, 3 H), 1.15-1.36 (m, 6 H), 1.39 (s, 9 H), 3.14 (m, 4 H),
4.30 (m, 1 H), 5.05 (brs, 1 H), 5.08 (brs, 1 H), 7.38 (d, 2 H),
7.81 (d, 2 H), 10.00 (s, 1 H).
Diben zyl 2-{4-[(2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-
oxo-3-(p en tyla m in o)p r op yl]ben zylid en e}m a lon a te (48).
Compound 47 (0.50 g, 1.38 mmol), dibenzyl malonate (0.47 g,
1.65 mmol), piperidine (0.023 g, 0.27 mmol), and HOAc (3
drops) in benzene (15 mL) were heated to reflux for 2 h. The
mixture was cooled to ambient temperature, diluted with
EtOAc (50 mL), and washed with 10% HCl/H2O (2 × 50 mL).
The organic layer was dried over Na2SO4, the solvent removed,
and the residue purified via SiO2 flash column chromatography
(eluant 2:1 hexane/EtOAc) to afford 0.060 g (70%) of 48 as a
slightly yellow oil: 1H NMR (CDCl3) δ 0.84 (t, 3 H), 1.17-
1.39 (m, 6 H), 1.40 (s, 9 H), 3.02 (m, 2 H), 3.13 (m, 2 H), 4.21
(m, 1 H), 5.00 (brs, 1 H), 5.28 (m, 4 H), 5.67 (brt, 1 H), 7.09 (d,
2 H), 7.32 (m, 12 H), 7.72 (s, 1 H).
4-{[(1S)-1-(4-{3-(Ben zyloxy)-2-[(ben zyloxy)ca r bon yl]-3-
oxo-1-p r op en yl}ben zyl)-2-oxo-2-(p en tyla m in o)eth yl]a m i-
n o}-4-oxobu ta n oic Acid (49). To a stirring solution of 48
(0.65 g, 1.03 mmol) in HOAc (10 mL) was added 1.5 M HCl/
HOAc (10 mL). The mixture was allowed to stand at ambient
temperature for 2 h and the solvent removed to afford 0.58 g
(quantitative) of the amine hydrochloride as a slightly yellow
amorphous solid: 1H NMR (DMSO) δ 0.76 (t, 3 H), 1.03 (m, 2
H), 1.17 (m, 4 H), 2.89 (m, 1 H), 3.02 (m, 3 H), 3.94 (m, 1 H),
5.25 (s, 2 H), 5.29 (s, 2 H), 7.22 (d, 2 H), 7.36 (m, 12 H), 7.73
(s, 1 H), 8.34 (brs, 2 H), 8.41 (t, 1 H).
To a stirring solution of the amine hydrochloride from above
(0.507 g, 0.89 mmol) in CH2Cl2 (15 mL) at 0 °C was added
triethylamine (0.20 g, 1.97 mmol), followed by succinic anhy-
dride (0.089 g, 0.89 mmol). The mixture was stirred for 16 h,
being allowed to warm to ambient temperature. The mixture
was diluted with CH2Cl2 (50 mL) and washed with 10% HCl/
H2O (2 × 50 mL). The organic layer was dried over Na2SO4
and solvent removed to afford 0.557 (99%) of 49 as a yellow
amorphous solid: 1H NMR (CDCl3) δ 0.83 (t, 3 H), 1.11-1.28
(m, 6 H), 2.47 (m, 2 H), 2.63 (m, 2 H), 3.03 (m, 4 H), 4.57 (q,
1 H), 5.25 (s, 2 H), 5.27 (m, 2 H), 5.93 (t, 1 H), 6.88 (d, 1 H),
7.09 (d, 2 H), 7.27 (m, 12 H), 7.70 (s, 1 H) (CO2H absent). Anal.-
(C36H40N2O8) C, H, N.
Meth yl 5-[(2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-oxo-
3-(p en tyla m in o)p r op yl]-2-(2-m eth oxy-2-oxoeth oxy)ben -
zoa te (55). A mixture of 54 (178 mg, 0.44 mmol), methyl
bromoacetate (124 µL, 1.31 mmol), and freshly ground K2CO3
(181 mg, 1.31 mmol) was suspended in acetone (4 mL). The
mixture was heated to 50 °C for 16 h. H2O (5 mL) was added
2-{4-[(2S )-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-oxo-3-
(p en tyla m in o)p r op yl]ben zylid en e}m a lon ic Acid (50). To

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 615
and the mixture was extracted with EtOAc (3 mL). The organic
layer was dried (MgSO4) and concentrated. The residue was
purified by flash chromatography (SiO2, EtOAc/n-hexane 1:1),
which furnished 192 mg (91%) of 55 as a white solid: 1H NMR
500 MHz (CDCl3) δ 0.87 (t, 3H, J ) 7.1, 14.6), 1.21 (m, 2H),
1.28 (m, 2H), 1.38 (m, 2H), 1.41 (s, 9H), 3.00 (m, 2H), 3.16
(dd, 2H, J ) 13.0, 6.6), 3.79 (s, 3H), 3.88 (s, 3H), 4.23 (dd, 1H,
J ) 14.1, 6.8), 4.70 (s, 2H), 5.10 (br t, 1H), 6.81 (d, 1H, J )
8.5), 7.29 (dd, 1H, J ) 8.5, 2.2), 7.66 (d, 1H, J ) 2.2).
500 MHz (DMSO) δ 0.83 (t, 3H, J ) 7.2, 15.0), 1.17 (m, 2H),
1.24 (m, 2H) 1.30 (m, 2H), 2.25-2.38 (m, 2H), 2.69 (dd, 1H),
2.88 (dd, 1H), 2.93 (m, 1H), 3.06 (m, 1H), 3.90 (s, 3H), 4.37
(m, 1H), 6.88 (d, 1H, J ) 8.5), 7.36 (dd, 1H, J ) 2.1, 8.5), 7.64
(d, 1H, J ) 2.1), 7.83 (t, 1H, J ) 5.5, 11.2), 8.06 (d, 1H, J )
8.4), 10.35 (s, 1H).
5-[(2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-oxo-3-(p en -
tyla m in o)p r op yl]-2-h yd r oxyben zoic Acid (59). A solution
of 58 (101 mg, 0.25 mmol) and 2.5 M aqueous LiOH (395 µL,
0.99 mmol) in THF/MeOH/H2O 3:1:1 (3 mL) was stirred at
ambient temperature for 16 h. The reaction mixture was
acidified with 10% aqueous HCl and extracted with EtOAc (4
× 2 mL). The organic layer was dried (MgSO4) and concen-
trated to dryness, which furnished 93 mg (96%) of 59 as a
white solid: 1H NMR 400 MHz (MeOH-d4) δ 0.89 (t, 3H, J )
7.1, 14.5), 1.19 (m, 2H), 1.29 (m, 2H), 1.41 (m, 2H), 2.43-2.60
(m, 4H), 2.86 (dd, 1H), 3.07 (m, 2H), 3.17 (m, 1H), 4.50 (m,
1H), 6.86 (d, 1H, J ) 8.5), 7.38 (dd, 1H, J ) 2.0, 8.5), 7.75 (d,
1H, J ) 2.0), 7.92 (br m, 1H), 8,25 (br d, 1H); 13C NMR (MeOH-
d4) δ 14.3, 23.3, 29.9, 30.0, 30.05, 31.3, 37.9, 40.4, 56.3, 114.1,
118.6, 129.5, 132.5, 138.0, 162.5, 173.5, 173.8, 174.9, 176.8.
MS (ESI) m/z 395 (M + H). Anal. (C21H28O9N2·1/3H2O) C, H.
Ben zyl 5-[(2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-oxo-
3-(p en tyla m in o)p r op yl]-2-h yd r oxyben zoa te (60) Triethy-
lamine (1.71 mL, 12.5 mmol) and benzyl alcohol (6.45 mL, 62
mmol) were added to a suspension of 53 (2.97 g, 6.23 mmol),
palladium(II)acetate (42 mg, 0.19 mmol), and 1,1′-bis(diphe-
nylphosphino)ferrocene (dppf, 207 mg, 0.37 mmol) in DMF (15
mL). The mixture was saturated with carbon monoxide (1 atm)
and stirred at 70 °C for 16 h. The mixture was allowed to reach
room temperature and extracted with EtOAc (40 mL). The
organic layer was washed with 10% aqueous HCl (20 mL) and
brine (20 mL), dried (Na2SO4), and concentrated. The residue
was purified by column chromatography (SiO2, EtOAc/n-
hexane 1:2), which furnished 5.7 g of a yellow oil. Crystalliza-
tion in EtOAc/n-hexane gave 0.82 g (27%) of pure 60 as a white
solid: 1H NMR 400 MHz (CDCl3) δ 0.84 (t, 3H, J ) 7.1, 14.4),
1.13 (m, 2H), 1.23 (m, 2H,), 1.35 (m, 2H), 1.39 (s, 9H), 2.95 (d,
2H, J ) 6.7), 3.11 (m, 2H), 4.18 (m, 1H), 5.07 (br m, 1H), 5.37
(d, 2H, J ) 1,7), 5.77 (br m, 1H), 6.91 (d, 1H, J ) 8.5), 7.30
(dd, 1H, J ) 2.2, 8.5), 7.35-7.47 (m, 5H), 7.69 (d, 1H, J )
2.2), 10.69 (1H, s).
Ben zyl 2-(2-Am in o-2-oxoeth oxy)-5-[(2S)-2-[(ter t-bu toxy-
ca r bon yl)a m in o]-3-oxo-3-(p en tyla m in o)p r op yl]ben zoa te
(61). A mixture of 60 (295 mg, 0.61 mmol), 2-bromoacetamide
(168 mg, 1.22 mmol), and freshly ground K2CO3 (168 mg, 1.22
mmol) was suspended in acetone (3 mL). The mixture was
stirred at 40 °C for 16 h, after which time H2O (5 mL) was
added and the mixture was extracted with EtOAc (2 × 5 mL).
The organic layer was washed with brine (4 mL), dried
(MgSO4), and concentrated in vacuo, which afforded 273 mg
(83%) of 61 as a white solid: 1H NMR 400 MHz (MeOH-d4) δ
0.88 (t, 3H, J ) 7.1, 14.4), 1.18 (m, 2H), 1.27 (m, 2H), 1.37 (s,
9H), 1.40 (m, 2H, partly obscured), 2.82 (dd, 1H, J ) 8.4, 13.5),
3.00-3.09 (m, 2H), 3.13 (m, 1H), 3.85 (s, 0.5H), 4.21 (br m,
1H), 4.56 (s, 2H), 5.36 (s, 2H), 7.07 (d, 1H, J ) 8.5), 7.36-7.49
(m, 6H), 7.81 (s, 1H).
Ben zyl 2-(2-Am in o-2-oxoeth oxy)-5-[(2S)-2-{[4-(ben z-
yloxy)-4-oxobu ta n oyl]a m in o}-3-oxo-3-(p en tyla m in o)p r o-
p yl]ben zoa te (62). Trifluoroacetic acid (0.55 mL, 7.12 mmol)
was carefully added to a stirring solution of 61 (257 mg, 0.47
mmol) in CH2Cl2 (4 mL) at 0 °C. The mixture was stirred for
4 h, the solution being allowed to warm to ambient tempera-
ture. The volatiles were removed in vacuo, and the residue
was partitioned between EtOAc (3 mL) and saturated aqueous
NaHCO3 (3 mL). The organic layer was dried (MgSO4) and
concentrated to dryness to afford 276 mg (>100%) of the crude
amine as a colorless oil. The amine was dissolved in DMF (3
mL) and cooled with ice. Benzyl hydrogen succinate (109 mg,
0.52 mmol) and EDC (100 mg, 0.52 mmol) were added, and
the mixture was stirred for 16 h, the solution being allowed
to warm to ambient temperature. The mixture was concen-
trated and partitioned between EtOAc (3 mL) and 10%
aqueous HCl (2 · 3 mL). The water layer was saturated with
4-{[(1S)-1-[3-(Met h oxyca r b on yl)-4-(2-m et h oxy-2-oxo-
eth oxy)ben zyl]-2-oxo-2-(p en tyla m in o)eth yl]a m in o}-4-ox-
obu ta n oic Acid (56). Trifluoroacetic acid (0.38 mL, 4.98
mmol) was carefully added to a stirring solution of 55 (159
mg, 0.33 mmol) in CH2Cl2 (3 mL) at 0 °C. The mixture was
stirred for 4 h, the solution being allowed to warm to ambient
temperature. The volatiles were removed in vacuo, and the
residue was partitioned between EtOAc (3 mL) and saturated
aqueous NaHCO3 (3 mL). The organic layer was dried (Mg-
SO4), and concentrated to dryness to afford 130 mg (quantita-
tive) of the crude amine as a colorless oil. The amine was
dissolved in CH2Cl2 (3 mL) and cooled with ice to 0 °C. Succinic
anhydride (33 mg, 0.33 mmol) and triethylamine (101 µL, 0.73
mmol) were added, and the mixture was stirred for 16 h, the
solution being allowed to warm to ambient temperature. The
mixture was diluted with CH2Cl2 (3 mL), and the organic phase
was washed with 10% aqueous HCl (2 × 3 mL), dried (MgSO4),
and concentrated. The residue was purified by flash chroma-
tography (SiO2, 5% MeOH in CH2Cl2, then 5% MeOH/1%
HOAc in CH2Cl2). The collected fractions were concentrated,
and the remaining HOAc was removed by azeotroping with
toluene on a rotavapor and then drying overnight under high
vacuum, which furnished 109 mg (69%) of 56 as a white solid:
1H NMR 400 MHz (MeOH-d4) δ 0.95 (t, 3H, J ) 7.1, 14.4),
1.29 (m, 2H), 1.38 (m, 2H), 1.48 (m, 2H), 2.43-2.64 (m, 4H),
2.91 (dd, 1H, J ) 13.8, 8.6), 3.13-3.22 (m, 3H), 3.82 (s, 3H),
3.92 (s, 3H), 4.55 (m, 1H), 4.83 (s, 2H), 7.00 (d, 1H, J ) 8.6),
7.43 (dd, 1H, J ) 8.6, 2.3), 7.72 (d, 1H, J ) 2.3), 7.97 (br t,
1H).
2-(Ca r boxym eth oxy)-5-[(2S)-2-[(3-ca r boxyp r op a n oyl)-
a m in o]-3-oxo-3-(p en tyla m in o)p r op yl]ben zoic Acid (57).
A solution of 56 (87 mg, 0.18 mmol) and 2.5 M aqueous LiOH
(435 µL, 1.1 mmol) in THF/MeOH/H2O 3:1:1 (3 mL) was stirred
at ambient temperature for 16 h. The reaction mixture was
acidified with 10% aqueous HCl and extracted with EtOAc (4
× 2 mL). The organic layer was dried (MgSO4) and concen-
trated to dryness, which furnished 68 mg (83%) of 57 as a
white solid: 1H NMR 400 MHz (MeOH-d4) δ 0.66 (t, 3H, J )
7.1, 14.4), 1.00 (m, 2H), 1.08 (m, 2H), 2.13-2.40 (m, 4H), 2.65
(dd, 1H, J ) 13.8, 8.6), 2.84-2.93 (m, 3H), 4.28 (m, 1H), 4.58
(s, 2H), 6.79 (d, 1H, J ) 8.6), 7.20 (dd, 1H, J ) 8.6, 2.2), 7.56
(d, 1H, J ) 2.2), 7.69 (br t, 1H); 13C NMR (MeOH-d4) δ 14.75,
23.78, 30.34, 30.47, 30.52, 31.74, 38.22, 40.87, 56.58, 67.67,
115.90, 121.69, 132.74, 134.38, 136.40, 158.14, 169.50, 172.65,
173.41, 174.97, 176.76; MS (ESI) 453 (M + H). Anal.
(C21H28O9N2·1/2H2O) C, H.
4-{[(1S)-1-[4-H yd r oxy-3-(m et h oxyca r b on yl)b en zyl]-2-
oxo-2-(pen tylam in o)eth yl]am in o}-4-oxobu tan oic Acid (58).
Trifluoroacetic acid (0.48 mL, 6.2 mmol) was carefully added
to a stirring solution of 54 (169 mg, 0.41 mmol) in CH2Cl2 (2
mL) at 0 °C. The mixture was stirred for 4 h, the solution being
allowed to warm to ambient temperature. The volatiles were
removed in vacuo, and the residue was partitioned between
EtOAc (3 mL) and saturated aqueous NaHCO3 (3 mL). The
organic layer was dried (MgSO4), and concentrated to dryness
to afford 124 mg (98%) of the crude amine as a colorless oil.
The amine was dissolved in CH2Cl2 (3 mL) and cooled with
ice to 0 °C. Succinic anhydride (41 mg, 0.40 mmol) and
triethylamine (124 µL, 0.89 mmol) were added, and the
mixture was stirred for 16 h, the solution being allowed to
warm to ambient temperature. The mixture was diluted with
CH2Cl2 (8 mL) and the organic layer was washed with 10%
aqueous HCl (2 × 3 mL), dried (MgSO4), and concentrated.
The residue was purified by flash chromatography as described
for 56, giving 111 mg (67%) of 58 as a white solid: 1H NMR

616 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
NaCl and extracted three times with EtOAc. The collected
organic layers were dried (MgSO4) and concentrated. The
residue was purified by flash chromatography (SiO2, EtOAc),
which furnished 93 mg (31%) of 62 as a white solid: 1H NMR
400 MHz (MeOH-d4) δ 0.88 (t, 3H, J ) 7.1, 14.5), 1.18 (m, 2H),
1.27 (m, 2H) 1.39 (m, 2H), 2.46 (m, 2H), 2.59 (m, 2H), 2.83
(dd, 1H), 3.09 (m, 3H), 4.51 (dd, 1H, J ) 6.3, 8.4), 4.55 (s, 2H),
5.10 (s, 2H), 5.35 (s, 2H), 7.04 (d, 1H, J ) 8.5), 7.3-7.5 (m,
11H), 7.80 (d, 1H, J ) 2.4), 7.89 (br t, 0.5H), 8.00 (s, 1H).
(2S)-(2-Am in o-2-oxoet h oxy)-5-[(2S)-2-[(3-ca r b oxyp r o-
pan oyl)am in o]-3-oxo-3-(pen tylam in o)pr opyl]ben zoic Acid
(63). A mixture of 62 (80 mg, 0.13 mmol) and 5% Pd/C (25
mg) in methanol (4 mL) was hydrogenated at atmospheric
pressure for 3 h. The mixture was filtered through Celite and
solvent removed in vacuo to afford 42 mg (71%) of 63 as a white
solid: 1H NMR 400 MHz (MeOH-d4) δ 0.90 (t, 3H, J ) 7.1,
14.4), 1.22 (m, 2H), 1.31 (m, 2H) 1.43 (m, 2H), 2.4-2.6 (m,
4H), 2.58 (m, 2H), 2.88 (dd, 1H, J ) 8.5, 14.8), 3.11 (m, 1H),
4.53 (dd, 1H, J ) 6.3, 8.5), 4.59 (s, 2H), 7.02 (d, 1H, J ) 8.5),
7.40 (dd, 1H, J ) 2.2, 8.5) 7.75 (d, 1H, J ) 2.2), 7.96 (br t,
0.5H); 13C NMR (MeOH-d4) δ 14.7, 23.8, 30.3, 30.5, 30.7, 31.9,
38.3, 40.8, 56.7, 69.2, 115.5, 123.7, 132.3, 133.9, 135.5, 157.8,
170.7, 173.5, 174.6, 175.0, 176.9. MS (ESI) m/z 452 (M + H).
Anal. (C21H29O8N3·H2O) C, H, N.
amine as a brown/yellow oil. The amine was dissolved in CH2-
Cl2 (6 mL) and cooled with ice. Succinic anhydride (54 mg, 0.54
mmol) and triethylamine (164 µL, 1.18 mmol) were added, and
the mixture was stirred for 16 h, the solution being allowed
to warm to ambient temperature. The mixture was diluted
with CH2Cl2 (10 mL), and the organic layer was washed with
10% aqueous HCl (2 × 5 mL), dried (MgSO4), and concen-
trated. The residue was purified by flash chromatography as
described for 56, which furnished 83 mg (33%) of 66 as a white
solid: 1H NMR 400 MHz (DMSO) δ 0.95 (t, 3H, J ) 7.0, 14.3),
1.28 (m, 2H), 1.36 (m, 2H), 1.43 (m, 2H), 2.35-2.49 (m, 4H),
2.82 (dd, 1H), 3.0-3.18 (m, 3H), 3.85 (s, 3H), 4.48 (m, 1H),
5.04 (s, 2H), 7.09 (d, 1H, J ) 8.5), 7.42 (br d, 1H, J ) 8.5),
7.74 (br s, 0.3H), 7.93 (br s, 1H), 8.01 (br m, 0.5H), 8.08 (br s,
0.4H), 8,24 (br d, 0.5H). Anal.(C22H31O8N2·0.5H2O) C, H.
4-{[(1S)-1-[3-(Am in oca r b on yl)-4-(ca r b oxym e t h oxy)-
ben zyl]-2-oxo-2-(pen tylam in o)eth yl]am in o}-4-oxobu tan o-
ic Acid (67). A solution of 66 (42 mg, 0.09 mmol) and 2.5 M
aqueous LiOH (72 µL, 0.18 mmol) in THF/MeOH/H2O 3:1:1
(1 mL) was stirred at ambient temperature for 16 h. The
reaction mixture was extracted with EtOAc (2 mL), and the
water layer was acidified with 10% aqueous HCl and extracted
with EtOAc (4 × 2 mL). The organic layer was dried (MgSO4)
and concentrated to dryness, which furnished 21 mg (42%) of
1
67 as a white solid: H NMR 400 MHz (MeOH-d4) δ 0.90 (t,
ter t-Bu tyl (1S)-1-[3-(Am in ocar bon yl)-4-h ydr oxyben zyl]-
2-oxo-2-(p en tyla m in o)-eth ylca r ba m a te (64). In a 50 mL
dried round-bottom flask were combined 53 (1.12 g, 2.34
mmol), palladium(II) acetate (16 mg, 3 mol %), and 1,1′-bis-
(diphenylphosphino)ferrocene (dppf, 78 mg, 6 mol %). DMF (5
mL) was added and a carbon monoxide atmosphere was
established in the reaction vessel. Diisopropylethylamine (0.82
mL, 4.69 mmol) and 1,1,1,3,3,3-hexamethyldisilazane (3.46
mL, 16.4 mmol) were added, and the reaction vessel was again
purged with successive cycles of carbon monoxide and vacuum
(five times). The mixture was stirred at 90 °C for 16 h. After
being cooled to ambient temperature, the reaction mixture was
acidified with 1 M aqueous HCl (pH 3-4) and stirred for about
5-10 min. The solution was then basified with 10 M aqueous
NaOH and extracted with EtOAc (2 × 5 mL). The organic layer
was dried (MgSO4) and concentrated. The resulting residue
was purified by flash chromatography (SiO2, EtOAc/n-hexane
2:1), which furnished 552 mg (60%) of 64 as a white solid: 1H
NMR 400 MHz (MeOH-d4) δ 0.89 (t, 3H, J ) 7.2, 14.5), 1.17
(m, 2H), 1.28 (m, 2H), 1.38 (m, 2H), 1.40 (s, 9H), 2.80 (dd, 1H,
J ) 7.9, 13.9), 2.98 (dd, 1H, J ) 7.6, 13.9), 3.05 (m, 1H), 3.18
(m, 1H), 4.22 (br t, 1H), 6.84 (d, 1H, J ) 8.5), 7.28 (dd, 1H, J
) 2.2, 8.5), 7.62 (d, 1H, J ) 2.2).
Meth yl {2-(Am in oca r bon yl)-4-[(2S)-2-[(ter t-bu toxyca r -
b on yl)a m in o]-3-oxo-3-(p en t yla m in o)p r op yl]p h en oxy}-
a ceta te (65). A mixture of 64 (340 mg, 0.86 mmol), methyl
bromoacetate (123 µL, 1.30 mmol), and freshly grounded K2-
CO3 (179 mg, 1.30 mmol) was suspended in acetone (7 mL).
The mixture was stirred at room temperature for 16 h, after
which time H2O (5 mL) was added and the mixture was
extracted with EtOAc (2 × 5 mL). The organic layer was
washed with brine (4 mL), dried (MgSO4), and concentrated
in vacuo, which afforded 370 mg (92%) of 65 as a white solid,
pure enough (>95%) to use in the next step without further
purification: 1H NMR 400 MHz (CDCl3) δ 0.86 (t, 3H, J )
7.1, 14.3), 1.19 (m, 2H), 1.27 (m, 2H), 1.39 (s, 9H), 1.36-1.40
(m, 2H), 2.98 (dd, 1H, J ) 7.0, 13.8), 3.09 (dd, 1H, J ) 6.8,
13.8), 3.17 (m, 2H), 4.27 (br m, 1H), 5.08 (br m 1H), 5.87 (br
m, 1H), 5.98 (br m, 1H), 6.78 (d, 1H, J ) 8.5), 7.34 (br dd,
1H), 8.08 (d, 1H, J ) 1.8), 8.32 (br s, 1H).
3H, J ) 7.1, 14.5), 1.22 (m, 2H), 1.31 (m, 2H), 1.41 (m, 2H),
2.40-2.62 (m, 4H), 2.89 (dd, 1H, J ) 8.8, 13.8), 3.08-3.19 (m,
3H), 4.53 (dd, 1H, J ) 6.1, 8.8), 4.82 (s, 2H), 7.03 (d, 1H, J )
8.5), 7.41 (dd, 1H, J ) 2.4, 8.5), 7.93 (d, 1H, J ) 2.4), 8.28 (d,
0.3H, J ) 7.9); 13C NMR (MeOH-d4) δ 14.7, 23.8, 30.2, 30.3,
30.5, 31.8, 38.3, 40.8, 56.6, 67.3, 114.7, 122.8, 132.4, 139.0,
135.6, 157.2, 169.9, 172.4, 173.5, 175.0, 176.8; MS (ESI) m/z
452 (M + H).
Meth yl 5-[(2S)-2-({(2S)-2-[(ter t-Bu toxycar bon yl)am in o]-
3-ph en ylpr opan oyl}am in o)-3-oxo-3-(pen tylam in o)pr opyl]-
2-(2-m eth oxy-2-oxoeth oxy)ben zoa te (68). Compound 55
(0.50 g, 1.0 mmol) was dissolved in a 4 M solution of HCl in
dioxane (5 mL). After stirring at room temperature for 2 h,
the solvent was removed under reduced pressure. The residue
was dissolved in CH2Cl2 (5 mL) and triethylamine (0.43 mL,
3.1 mmol), and N-(tert-butoxycarbonyl)-L-phenylalanine (0.28
g, 1.0 mmol) was added. After the mixture was cooled to 0 °C,
EDC (0.20 g, 1.0 mmol) and HOBT (0.14 g, 1.0 mmol) were
added. The mixture was warmed to room temperature and
stirred overnight. The mixture was partitioned between EtOAc
and 1 M HCl. The organic phase was washed with sat.
NaHCO3 and sat. NaCl, dried (MgSO4), and concentrated to a
glassy solid (0.54 g). The residue was purified by flash
chromatography (40 g SiO2, 60% EtOAc/heptane) to obtain 0.42
g (67%) of 68 as a white powder: 1H NMR (CDCl3) δ 7.48 (br
s, 1 H), 7.30 (m, 3 H), 7.18 (m, 3 H), 6.76 (d, 1 H), 6.32 (br s,
1 H), 6.00 (br s, 1 H), 4.90 (br s, 1 H), 4.68 (s, 3 H), 4.55 (m, 1
H), 4.25 (m, 1 H), 3.88 (s, 3 H), 3.78 (s, 3 H), 3.07 (m, 4 H),
2.90 (m, 2 H), 1.40-1.20 (m, 15 H), 0.86 (t, 3 H).
5-[(2S )-2-({(2S )-2-[(t er t -b u t o x y c a r b o n y l)a m in o ]-3-
p h en ylp r op a n oyl}a m in o) 3-oxo-3-(p en tyla m in o)p r op yl]-
2-(ca r boxym eth oxy)ben zoic a cid (69) was prepared by
saponification of 68 with LiOH as described in the preparation
of 38: 1H NMR (DMSO-d6) δ 7.92 (br s, 1 H), 7.54 (br s, 1 H),
7.30 (d, 1 H), 7.18 (m, 6 H), 6.90 (d, 1 H), 4.68 (s, 2 H), 4.40
(m, 1 H), 4.05 (m, 1 H), 2.98 (m, 2 H), 2.83 (m, 2 H), 2.65 (m,
2 H), 1.33-1.10 (m, 15 H), 0.82 (t, 3 H); MS (FAB) m/z (rel
intensity) 600 (MH+, 21), 622 (15), 600 (21), 501 (30), 500 (99),
238 (11), 120 (73), 88 (34), 57 (52), 43 (12), 41 (14); HRMS
(FAB) calcd for C31H41N3O9 + H 600.2921, found 600.2923.
Anal. (C31H41N3O9·0.38H2O) C, H, N.
4-{[(1S )-1-[3-(Am in oca r b on yl)-4-(2-m e t h oxy-2-oxo-
eth oxy)ben zyl]-2-oxo-2-(pen tylam in o)eth yl]am in o}-4-oxo-
bu ta n oic Acid (66). Trifluoroacetic acid (0.74 mL, 9.63 mmol)
was carefully added to a stirring solution of 65 (299 mg, 0.64
mmol) in CH2Cl2 (5 mL) at 0 °C. The mixture was stirred for
3 h, the solution being allowed to warm to ambient tempera-
ture. The volatiles were removed in vacuo, and the residue
was partitioned between EtOAc (4 mL) and saturated aqueous
NaHCO3 (3 mL). The organic layer was dried (MgSO4), and
concentrated to dryness to afford 196 mg (84%) of the crude
Meth yl 5-[(2S)-2-({(2S)-2-[(4-m eth oxy-4-oxobu ta n oyl)-
a m in o]-3-p h en ylp r op a n oyl}a m in o)-3-oxo-3-(p en tyla m i-
n o)p r op yl]-2-(2-m eth oxy-2-oxoeth oxy)ben zoa te (70) was
prepared by removal of the Boc group from 68 with HCl/
dioxane followed by coupling with monomethyl succinate with
EDC and HOBT as described for the preparation of 13 from
11a : 1H NMR (CDCl3) δ 7.69 (d, J ) 2 Hz, 1 H), 7.35 (dd, J )
8, 2 Hz, 1 H), 7.23 (m, 4 H), 7.10 (m, 2 H), 6.80 (d, J ) 8 Hz,

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 617
1 H), 6.51 (d, J ) 7 Hz, 1 H), 6.40 (bt, J ) 6 Hz, 1 H), 4.71 (s,
2 H), 4.56 (m, 2 H), 3.92 (s, 3 H), 3.77 (s, 3 H), 3.64 (s, 3 H),
3.35 (dd, J ) 4, 15 Hz, 1 H), 3.15 (m, 3 H), 2.95 (m, 2 H), 2.2-
2.7 (m, 4 H), 1.45 (m, 2 H), 1.2-1.4 (m, 4 H), 0.89 (t, J ) 7 Hz,
3 H); MS (FAB) m/z (rel intensity) 642 (MH+, 89), 643 (32),
642 (89), 234 (39), 120 (99), 115 (61), 73 (32), 57 (43), 55 (29),
43 (44), 41 (26); HRMS (FAB) calcd for C33H43N3O10 + H
642.3026, found 642.3032. Anal. (C33H43N3O10·0.37H2O)
C, H, N.
(14), 543 (45), 542 (5), 441 (6), 92 (9), 91 (99), 88 (23), 86 (6),
43 (6); HRMS (FAB) calcd for C28H34N2O9 + H 543.2343, found
543.2332.
2-{4-[(2S)-2-[(4-Am in o-4-oxobu ta n oyl)a m in o]-3-oxo-3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon ic Acid (76). To a
suspension of succinamic acid (40 mg, 0.34 mmol) in CH2Cl2
(1 mL) at 0 °C was added EDC (65 mg, 0.34 mmol) and HOBT
(46 mg, 0.34 mmol), and the mixture was stirred for a few
minutes. Compound 12b (150 mg, 0.34 mmol) and triethy-
lamine (48 mL, 0.34 mmol) were added, and the mixture was
warmed to room temperature and stirred overnight. The
mixture was partitioned between EtOAc and 1 M HCl. The
organic phase was washed with sat. NaHCO3 and sat. NaCl
and dried (MgSO4). After the solvent was removed under
reduced pressure, the residue was purified by flash chroma-
tography (11 g SiO2, 6% MeOH/CH2Cl2) to yield 72 mg of a
white solid. To a solution of the solid dissolved in THF (3 mL)
and MeOH (1 mL) was added a solution of LiOH·H2O (30 mg,
0.71 mmol) in H2O (1 mL). The mixture was stirred at room
temperature for 2.5 h. The mixture was neutralized with 1 M
HCl and extracted with EtOAc (3×). The combined organic
phase was washed with sat. NaCl and dried (MgSO4). The
solvent was removed in vacuo to give 27 mg (18%) of 76 as a
white solid: 1H NMR (DMSO) δ 8.05 (d, 1 H), 7.85 (t, 1 H),
7.27 (br s, 1 H), 1.12 (d, 2 H), 6.79 (d, 2 H), 6.75 (br s, 1 H),
5.26 (s, 1 H), 4.30 (m, 1 H), 2.89-3.03 (m, 3 H), 2.89-3.03 (m,
3 H), 2.60-2.71 (m, 1 H), 2.12-2.32 (m, 4 H), 1.11-1.38 (m, 6
H), 0.83 (t, 3 H); MS (ES-) 450; HRMS (FAB) calcd for
2-(Ca r boxym eth oxy)-5-[(2S)-2-({(2S)-2-[(3-ca r boxyp r o-
p a n oyl)a m in o]-3-p h en ylp r op a n oyl}a m in o)-3-oxo-3-(p en -
tyla m in o)p r op yl]ben zoic a cid (71) was prepared by sa-
ponification of 70 with LiOH as described for the preparation
of 38: 1H NMR (DMSO-d6) δ 8.10 (d, 1 H), 8.00 (d, 1 H), 7.78
(t, 1 H), 7.53 (d, 1 H), 7.29 (dd, 1 H), 7.16 (m, 5 H), 6.90 (d, 1
H), 4.71 (s, 2 H), 4.37 (m, 2 H), 2.95 (m, 4 H), 2.70 (m, 2 H),
2.29 (m, 4 H), 1.35-1.15 (m, 6 H), 0.82 (t, 3 H); MS (FAB) m/z
(rel intensity) 600 (MH+, 20), 600 (20), 353 (12), 248 (11), 238
(12), 220 (15), 131 (9), 121 (10), 120 (99), 88 (32), 43 (11); HRMS
(FAB) calcd for C30H37N3O10 + H 600.2557, found 600.2564.
Anal. (C30H37N3O10·0.87H2O) C, H, N.
2-{4-[(2R )-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-oxo-3-
(p en t yla m in o)p r op yl]p h en oxy}m a lon ic a cid (72) was
prepared by the method described for the synthesis of 8 from
N-Boc-D-tyrosine: MS (ES-) 451. Anal. C21H28N2O9·0.64H2O)
C, H, N.
4-{[(1S)-1-{4-[2-Eth oxy-1-(eth oxycar bon yl)-2-oxoeth oxy]-
ben zyl}-2-oxo-2-(pen tylam in o)eth yl]am in o}-4-oxobu tan o-
ic Acid (73). To a solution of 13b (R3 ) CH2CH2CO2Bn) (79
mg, 0.145 mmol) in MeOH (2 mL) was added 10% Pd/C (8 mg).
The mixture was stirred at room temperature under an
atmosphere of hydrogen (balloon) for 1 h. The mixture was
filtered through Celite and concentrated. The resulting oil was
dissolved in CH2Cl2 (0.5 mL) and cooled to 0 C. Succinic
anhydride (14 mg, 0.145 mmol) was added, and the mixture
was stirred at room temperature overnight. The mixture was
diluted with EtOAc (20 mL) and washed with 0.5 M HCl (10
mL) and sat. NaCl (10 mL). After drying (MgSO4), the organic
phase was concentrated to provide 71 mg (96%) of 73 as a
glass: 1H NMR (CDCl3) δ 7.12 (d, J ) 9 Hz, 2 H), 6.87 (d, J )
9 Hz, 2 H), 6.60 (br s, 1 H), 5.80 (br s, 1 H), 5.17 (s, 1 H), 4.52
(dd, J ) Hz, 1 H), 4.32 (m, 4 H), 3.14 (dd, J ) 13, 6.5 Hz, 2 H),
2.96-3.03 (m, 2 H), 2.63-2.67 (m, 2 H), 2.45-2.50 (m, 2 H),
1.17-1.42 (m, 12 H), 0.87 (t, J ) 7 Hz, 3 H); MS (FAB) m/z
509 (MH+), 531, 510, 509, 391, 294, 265, 88, 86, 43, 29;
C
21H29N3O8 + H 452.2032; found 452.2051.
2-{4-[(2S )-2-[(4-C a r b o x y b u t a n o y l)a m in o ]-3-o x o -3-
(p en t yla m in o)p r op yl]p h en oxy}m a lon ic a cid (77) was
prepared by the general procedure described for the prepara-
tion of 14 from 12a : 1H NMR (DMSO) δ 0.84 (t, 3 H), 1.15-
1.36 (m, 6 H), 1.61 (t, 2 H), 2.06 (m, 4 H), 2.68 (m, 1 H), 2.84
(m, 1 H), 3.00 (m, 2 H), 4.38 (m, 1 H), 5.25 (s, 1 H), 6.80 (d, 2
H), 7.13 (d, 2 H), 7.86 (t, 1 H), 8.00 (d, 1 H) (3-CO2H absent);
MS (FAB) m/z (rel intensity) 467 (MH+, 99), 481 (18), 468 (24),
467 (99), 423 (20), 238 (15), 194 (14), 91 (13), 88 (72), 59 (14),
43 (16). Anal. (C22H30N2O9·0.82H2O) C, H, N.
2-{4-[(2S)-2-{[2-(2-Hydr oxy-2-oxoeth oxy)acetyl]am in o}-
3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (78)
was prepared by the general procedure described for the
preparation of 14 from 12a : 1H NMR (DMSO) δ 0.83 (t, 3 H),
1.20-1.32 (m, J ) Hz, 6 H), 2.76-3.01 (m, 4 H), 3.89 (s, 2 H),
4.03 (s, 2 H), 4.45 (m, 1 H), 5.23 (s, 1 H), 6.78 (d, 2 H), 7.08 (d,
2 H), 7.77 (d, 1 H), 7.95 (t, 1 H) (3-CO2H absent); MS (FAB)
m/z (rel intensity) 469 (MH+, 22), 497 (40), 483 (53), 469 (22),
107 (22), 88 (99), 86 (22), 75 (22), 43 (52), 39 (22), 23 (28). Anal.
(C21H28N2O10·0.89H2O) C, H, N.
2 -{4 -[(2 S )-2 -[(2 -C a r b o x y a c e t y l )a m i n o ]-3 -o x o -3 -
(p en t yla m in o)p r op yl]p h en oxy}m a lon ic a cid (79) was
prepared by the general procedure described for the prepara-
tion of 14 from 12a : 1H NMR (DMSO) δ 0.82 (t, 3 H), 1.19-
1.31 (m, 6 H), 2.69 (m, 1 H), 2.85-3.21 (m, 5 H), 4.37 (m, 1
H), 5.23 (s, 1 H), 6.78 (d, 2 H), 7.09 (d, 2 H), 7.86 (t, 1 H), 8.27
(d, 1 H) (3-CO2H absent); MS (FAB) m/z (rel intensity) 439
(MH+, 99), 453 (41), 440 (13), 439 (99), 395 (10), 331 (18), 177
(81), 133 (13), 118 (35), 88 (94), 23 (17). Anal. (C20H26N2O9·
0.73H2O) C, H, N.
2-{4-[(2S)-2-[(4-Ca r boxy-3,3-d im eth ylbu ta n oyl)a m in o]-
3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (80)
was prepared by the general procedure described for the
preparation of 14 from 12a : 1H NMR (DMSO) δ 0.85 (m, 9
H), 1.11-1.40 (m, 6 H), 2.12 (m, 4 H), 2.67 (m, 1 H), 2.85 (m,
1 H), 2.98 (m, 2 H), 5.22 (m, 1 H), 5.73 (s, 1 H), 6.78 (d, 2 H),
7.11 (d, 2 H), 7.84 (t, 1 H), 7.97 (d, 1 H) 3-CO2H absent). Anal.
(C24H34N2O9·1.27H2O) C, H, N.
HRMS (FAB) calcd for C25H36N2O9 + H 509.2499, found
509.2494.
4-Oxo-4-{[(1S)-2-oxo-2-(p en tyla m in o)-1-(4-{[(tr iflu or o-
m eth yl)su lfon yl]oxy}ben zyl)eth yl]a m in o}bu ta n oic Acid
(74). The title compound was prepared as described for 42
using trifluoromethanesulfonic anhydride, but without the use
of methanol in the hydrolysis. After the workup, a white solid
was obtained. Recrystallization from acetonitrile gave an
1
amorphous solid (43%): mp 140.2-142.7 °C; H NMR (CD3-
OD) δ 0.91 (t, J ) 7.3, 3H), 1.19-1.37 (m, 4H), 1.40-1.47 (m,
2H), 2.37-2.70 (m, 4H), 2.95 (dd, J 1,2 ) 8.7, 1H), 3.07-3.24
(m, 3H), 4.58 (dd, J 1 ) 8.9, J 2 ) 8.7, 1H), 7.29 (d, J ) 8.7, 2H),
7.41 (d, J ) 8.7, 2H); 13C NMR (CD3OD) δ 15.52, 24.54, 31.11,
31.23, 31.28, 32.50, 39.31, 41.56, 57.11, 121.33 (q, J ) 319.8,
CF3), 123.51, 133.56, 141.48, 151.07, 174.01, 175.74, 177.54;
MS (ionspray, [M - H]-) m/z 481.4. Anal. (C19H25F3N2O7S) H,
N; C: calcd, 47.30; found, 48.03.
2-{4-[(2S)-2-{[4-(Ben zyloxy)-4-oxob u t a n oyl]a m in o}-3-
oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic Acid (75).
Trifluoroacetic acid (5 mL) was added to a solution of 7 (225
mg, 0.344 mmol) in methylene chloride (5 mL) with ice-bath
chilling. The solution was stirred at room temperaturefor 2 h.
Concentration in vacuo afforded the title compound as a light
amber foam: 1H NMR (CD3OD) 7.33 (m, 5 H), 7.15 (d, J ) 9
Hz, 2 H), 6.89 (d, J ) 9 Hz, 2 H), 5.23 (s, 1 H), 5.10 (s, 2 H),
4.48 (m, 1 H), 3.05 (m and dd obscured, 3 H), 2.80 (dd, J ) 7,
14 Hz, 1 H), 2.35-2.7 (m, 4 H), 1.1-1.5 (m, 6 H), 0.88 (t, J )
7 Hz, 3 H); MS (FAB) m/z (rel intensity) 543 (M + H, 45), 544
2-{4-[(2S)-2-({2-[1-(Car boxym eth yl)cyclopen tyl]acetyl}-
a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic
a cid (81) was prepared by the general procedure described
for the preparation of 14 from 12a : 1H NMR (DMSO) δ 0.82
(t, 3 H), 1.20-1.47 (m, 14 H), 2.18-2.35 (m, 4 H), 2.60-2.92
(m, 2 H), 2.99 (q, 2 H), 4.40 (m, 1 H), 5.22 (s, 1 H), 7.79 (d, 2
H), 7.11 (d, 2 H), 7.83 (t, 1 H), 8.00 (d, 1 H) (3-CO2H absent);

618 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
MS (FAB) m/z (rel intensity) 462 (MH+, 0), 535 (48), 521 (36),
143 (36), 136 (33), 109 (40), 88 (99), 81 (83), 67 (37), 43 (42),
39 (37). Anal. (C26H36N2O9·H2O) C, H, N.
165.04, 173.80, 175.01, 176.83; MS (ionspray, [M + H]+) m/z
437.2. Anal. (C20H26N2O9·1.5H2O) C, H, N.
2-{4-[(2S)-2-[(3-Car boxypr opan oyl)am in o]-3-(decylam i-
n o)-3-oxop r op yl]p h en oxy}m a lon ic a cid (89) was prepared
by the general procedure described for the preparation of 30
from 28b: 1H NMR (DMSO) δ 8.06 (d, 1 H), 7.80 (t, 1 H), 7.10
(d, 2 H), 6.78 (d, 2 H), 5.24 (s, 1 H), 3.33 (q, 1 H), 2.98 (m, 2
H), 2.85 (dd, 1 H), 2.65 (dd, 1 H), 2.30 (m, 4 H), 1.21 (m, 16
H), 0.83 (t, 3 H); HRMS (FAB) calcd for C26H38N2O9 + H
523.2655; found 523.2634. Anal. (C26H38N2O9) C, H, N.
2-(4-{(2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-[(cyclo-
h exylm eth yl)a m in o]-3-oxop r op yl}p h en oxy)m a lon ic a cid
(90) was prepared by the general procedure described for the
preparation of 30 from 28a : 1H NMR (DMSO) δ 0.78 (m, 2 H),
1.12 (m, 3 H), 1.32 (m, 1 H), 1.62 (m, 5 H), 2.30 (m, 4 H), 2.62-
2.92 (m, 4 H), 4.32 (m, 1 H), 5.22 (s, 1 H), 6.78 (d, 2 H), 7.09
(m, 2 H), 7.76 (t, 1 H), 8.02 (d, 1 H) (3-CO2H absent); MS (FAB)
m/z (rel intensity) 479 (MH+, 99), 480 (20), 479 (99), 435 (26),
331 (15), 177 (46), 127 (19), 114 (48), 71 (12), 57 (12), 55 (17);
HRMS (FAB) calcd for C23H30N2O9 + H 479.2029, found
479.2029. Anal. (C23H30N2O9·0.49H2O) C, H, N.
2-{4-[(2S)-2-[(3-Car boxypr opan oyl)am in o]-3-(isopen tyl-
a m in o)-3-oxop r op yl]p h en oxy}m a lon ic a cid (91) was pre-
pared by the general procedure described for the preparation
of 30 from 28a : 1H NMR (DMSO) δ 0.83 (d, 6 H), 1.22 (m, 2
H), 1.48 (m, 1 H), 2.32 (m, 4 H), 2.75 (m, 1 H), 2.82 (m, 1 H),
3.00 (m, 2 H), 4.35 (m, 1 H), 5.22 (s, 1 H), 6.78 (d, 2 H), 7.09
(d, 2 H), 7.74 (t, 1 H), 8.04 (d, 1 H) (3-CO2H absent); MS (FAB)
m/z (rel intensity) 453 (MH+, 22), 475 (20), 453 (22), 431 (15),
194 (18), 136 (18), 88 (99), 86 (15), 55 (14), 43 (30), 23 (43).
Anal. (C21H28N2O9·0.60H2O) C, H, N.
2-(4-{(2S)-2-[(3-Ca r boxyp r op a n oyl)a m in o]-3-oxo-3-[(3-
p h en ylp r op yl)a m in o]p r op yl}p h en oxy)m a lon ic a cid (92)
was prepared by the general procedure described for the
preparation of 30 from 28b: 1H NMR (DMSO) δ 8.10 (d, 1 H),
7.89 (t, 1 H), 7.25 (t, 2 H), 7.15 (m, 5 H), 6.80 (d, 2 H), 5.23 (s,
1 H), 4.33 (m, 1 H), 3.01 (m, 2 H), 2.89 (dd, 1 H), 2.70 (m, 1
H), 2.32 (m, 4 H), 1.61 (m, 2 H); MS (ES-) 499. Anal.
(C25H28N2O9·0.73H2O) C, H, N.
2-(4-{(2S)-2-[(3-Ca r boxyp r op a n oyl)a m in o]-3-[(1-n a p h -
th ylm eth yl)a m in o]-3-oxop r op yl}p h en oxy)m a lon ic a cid
(93) was prepared by the general procedure described for the
preparation of 30 from 28b: 1H NMR (DMSO) δ 8.45 (t, 1 H),
8.17 (d, 2 H), 8.00 (m, 1 H), 7.92 (m, 1 H), 7.81 (d, 1 H), 7.41
(m, 2 H), 7.41 (t, 1 H), 7.25 (d, 1 H), 7.11 (d, 2 H), 6.77 (d, 2
H), 5.25 (s, 1 H), 4.70 (d, 2 H), 4.50 (m, 1 H), 3.94 (dd, 1 H),
2.72 (dd, 1 H), 2.32 (m, 4 H); MS (ES-) 521; HRMS (FAB)
calcd for C27H26N2O9 + H 523.1716, found 523.1722.
2-(4-{(2S)-2-[(3-Car boxypr opan oyl)am in o]-3-[(3,3-diph e-
n ylpr opyl)am in o]-3-oxopr opyl}ph en oxy)m alon ic acid (94)
was prepared by the general procedure described for the
preparation of 30 from 28b: 1H NMR (DMSO) δ 8.04 (d, 1 H),
7.90 (t, 1 H), 7.25 (m, 8 H), 7.12 (m, 4 H), 6.77 (d, 2 H), 5.22
(s, 1 H), 4.34 (q, 1 H), 3.92 (t, 1 H), 2.89 (m, 3 H), 2.65 (m, 1
H), 2.31 (m, 4 H), 2.10 (q, 2 H); MS (ES+) 577. Anal.
(C31H32N2O9·0.9H2O) C, H, N.
2-{4-[(2S)-2-({[(1R,2S)-2-Ca r boxycycloh exyl]ca r bon yl}-
a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic
a cid (82) was prepared by the general procedure described
for the preparation of 14 from 12a : 1H NMR (DMSO) δ 0.84
(m, 3 H), 1.12-1.50 (m, 14 H), 1.80 (m, 1 H), 2.4-3.15 (m, 4
H), 3.35 (m, 1 H), 5.22 (m, 1 H), 6.65 (d, 0.2 H), 6.78 (d, 1.8
H), 7.0 (d, 0.2 H), 7.08 (m, 1.8 H), 7.22 (m, 1 H), 7.62 (m, 1 H),
7.75 (d, 1 H) (3-CO2H absent); MS (FAB) m/z (rel intensity)
507 (MH+, 99), 508 (28), 507 (99), 238 (42), 194 (38), 136 (26),
102 (37), 91 (31), 88 (78), 81 (66), 43 (30). Anal. (C25H34N2O9·
0.87H2O) C, H, N.
2-{4-[(2S)-2-({[(1R,2R)-2-Ca r boxycycloh exyl]ca r bon yl}-
a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic
a cid (83) was prepared by the general procedure described
for the preparation of 14 from 12a : 1H NMR (DMSO) δ 0.82
(m, 3 H), 1.20 (m, 8 H), 1.53-1.96 (m, 4 H), 2.40 (m, 2 H),
2.54-2.89 (m, 2 H), 3.00 (m, 4 H), 4.29 (m, 1 H), 5.23 (m, 1
H), 6.76 (d, 2 H), 7.08 (m, 2 H), 7.52 (m, 1 H), 7.90 (m, 1 H)
(3-CO2H absent); MS (FAB) m/z (rel intensity) 507 (MH+, 99),
508 (29), 507 (99), 353 (35), 238 (24), 194 (19), 143 (18), 109
(15), 88 (63), 81 (41), 43 (17). Anal. (C25H34N2O9·1.6H2O) C, H,
N.
2-{4-[(2S)-2-{[(2-Car boxycyclopr opyl)car bon yl]am in o}-
3-oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (84)
was prepared by the general procedure described for the
preparation of 14 from 12a : 1H NMR (DMSO) δ 0.82 (t, 3 H),
1.22 (m, 8 H), 1.92 (m, 2 H), 2.72 (m, 1 H), 2.98 (m, 3 H), 4.32
(m, 1 H), 5.24 (s, 1 H), 6.78 (d, 2 H), 7.09 (m, 2 H), 7.82 (m, 1
H), 8.40 (m, 1 H) (3-CO2H absent); MS (FAB) m/z (rel intensity)
465 (MH+, 99), 466 (27), 465 (99), 421 (18), 238 (10), 194 (12),
113 (15), 107 (24), 102 (11), 88 (39), 63 (11). Anal. (C22H28N2O9·
0.88H2O) C, H, N.
2-{4-[(2S )-2-[(2-C a r b o x y b e n z o y l)a m i n o ]-3-o x o -3-
(p en t yla m in o)p r op yl]p h en oxy}m a lon ic a cid (85) was
prepared by the general procedure described for the prepara-
tion of 14 from 12a : 1H NMR (DMSO) δ 0.83 (t, 3 H), 1.22 (m,
4 H), 1.40 (m, 2 H), 2.73 (dd, 1 H), 3.08 (m, 3 H), 4.50 (m, 1
H), 5.27 (s, 1 H), 6.83 (d, 2 H), 6.97 (d, 1 H), 7.15 (d, 2 H), 7.50
(m, 2 H), 7.70 (t, 1 H), 7.89 (d, 1 H), 8.52 (d, 1 H) (3-CO2H
absent); MS (FAB) m/z (rel intensity) 501 (MH+, 54), 501 (54),
154 (64), 149 (23), 137 (71), 117 (33), 109 (30), 92 (22), 59 (99),
45 (24), 41 (24). Anal. (C25H28N2O9·1.28H2O) C, H, N.
2-{4-[(2S)-2-({[(1R,4R)-3-Ca r b oxyb icyclo[2.2.1]h ep t -2-
y l]c a r b o n y l}a m in o )-3-o x o -3-(p e n t y la m in o )p r o p y l]-
p h en oxy}m a lon ic a cid (86) was prepared by the general
procedure described for the preparation of 14 from 12a : 1H
NMR (DMSO) δ 0.80 (m, 4 H), 1.21 (m, 7 H), 1.43-2.10 (m, 2
H), 2.12-2.42 (m, 2 H), 2.60-3.10 (m, 8 H), 4.34 (m, 1 H), 5.15
(m, 1 H), 6.75 (m, 2 H), 7.05 (m, 2 H), 7.60 (m, 1 H), 7.80 (m,
1 H) (3-CO2H absent); MS (FAB) m/z (rel intensity) 519 (MH+,
99), 519 (99), 353 (53), 238 (31), 194 (32), 177 (40), 167 (34),
88 (61), 67 (48), 43 (47), 23 (45). Anal. C26H34N2O9·0.90H2O)
C, H, N.
2-(4-{(2S)-3-(Hexyla m in o)-2-[(4-h yd r oxy-4-oxobu ta n o-
yl)a m in o]-3-oxop r op yl}p h en oxy)m a lon ic a cid (87) was
prepared by the general procedure described for the prepara-
tion of 30 from 28a : 1H NMR (DMSO) δ 0.82 (t, 3 H), 1.19 (m,
8 H), 2.32 (m, 4 H), 2.66 (m, 1 H), 2.90 (m, 3 H), 4.32 (m, 1 H),
5.22 (s, 1 H), 6.76 (d, 2 H), 7.09 (d, 2 H), 7.77 (t, 1 H), 8.03 (d,
2-(4-{(2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-[(2,2-d i-
eth oxyeth yl)a m in o]-3-oxop r op yl}p h en oxy)m a lon ic a cid
(95) was prepared by the general procedure described for the
preparation of 30 from 28a : 1H NMR (DMSO) δ 1.07 (m, 6 H),
2.30 (m, 1 H), 2.66 (m, 1 H), 2.85 (m, 1 H), 3.15 (m, 2 H), 3.42
(m, 2 H), 3.55 (m, 2 H), 4.38 (m, 4 H), 5.25 (s, 1 H), 5.73 (s, 1
H), 6.78 (d, 2 H), 7.12 (d, 2 H), 7.92 (m, 1 H), 8.06 (m, 1 H)
(3-CO2H absent); MS (FAB) m/z (rel intensity) 499 (MH+, 8),
453 (80), 251 (99), 194 (45), 177 (53), 136 (66), 107 (38), 101
(44), 88 (89), 57 (61), 23 (81). Anal. (C22H30N2O11·1.20H2O) C,
H, N.
2-(4-{(2S)-3-{[4-(Am in osu lfon yl)p h en et h yl]a m in o}-2-
[(3-ca r b oxyp r op a n oyl)a m in o]-3-oxop r op yl}p h en oxy)-
m a lon ic a cid (96) was prepared by the general procedure
described for the preparation of 30 from 28b: 1H NMR (DMSO)
δ 8.09 (d, 1 H), 8.00 (t, 1 H), 7.71 (d, 2 H), 7.35 (d, 2 H), 7.27
(s, 2 H), 5.27 (s, 1 H), 4.33 (m, 1 H), 2.84 (dd, 1 H), 2.60-2.77
1 H) (3-CO2H absent); HRMS (FAB) calcd for C22H30N2O9
H 467.2029, found 467.2040. Anal. (C22H30N2O9·0.59H2O) C,
H, N.
+
2-(4-{(2S)-3-(Bu tyla m in o)-2-[(3-ca r boxyp r op a n oyl)a m i-
n o]-3-oxop r op yl}p h en oxy)m a lon ic a cid (88) was prepared
by the general procedure described for the preparation of 30
from 28a : 1H NMR (CD3OD) δ 0.85 (t, 3H), 1.17-1.26 (m, 2H),
1.33-1.40 (m, 2H), 2.29-2.58 (m, 4H), 2.78 (dd, 1H), 3.01-
3.11 (m, 3H), 4.44 (dd, 1H), 5.12 (s, 1H), 6.86 (d, 2H), 7.11 (d,
2H);13C NMR (CD3OD) δ 14.50, 21.38, 30.54, 31.78, 32.73,
38.39, 40.57, 40.70, 56.58, 116.67, 131.74, 132.34, 157.96,

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 619
(m, 3 H), 2.31 (m, 4 H); MS (ES-) 564. Anal. (C24H27N3O11S·
1.34H2O) C, H, N.
(m, 4 H), 4.02 (m, 1 H), 5.00 (s, 1 H), 6.78 (d, 2 H), 7.12 (d, 2
H), 7.30 (s, 1 H), 7.63 (s, 1 H), 7.71 (s, 1 H) (NH's, 3-CO2H
absent); MS (FAB) m/z (rel intensity) 491 (MH+, 1), 505 (3),
383 (8), 357 (4), 236 (11), 222 (23), 174 (76), 127 (17), 124 (7),
118 (8), 107 (99).
2-(4-{(2S)-3-{[(1S)-1-(Am in oca r bon yl)p en tyl]a m in o}-2-
[(3-ca r b oxyp r op a n oyl)a m in o]-3-oxop r op yl}p h en oxy)-
m a lon ic a cid (105) was prepared by the general procedure
described for the preparation of 30 from 28b, using (S)-
norleucine amide as the amine component: 1H NMR (DMSO)
δ 0.83 (t, 3 H), 1.19 (m, 4 H), 1.53 (m, 1 H), 1.68 (m, 1 H), 2.30
(m, 4 H), 2.71 (m, 1 H), 2.95 (m, 1 H), 4.02 (m, 1 H), 4.40 (m,
1 H), 5.30 (s, 1 H), 6.79 (d, 2 H), 6.99 (s, 1 H), 7.09 (s, 1 H),
7.13 (d, 2 H), 7.80 (d, 1 H), 8.10 (d, 1 H) (3-CO2H absent);
HRMS (FAB) calcd for C22H29N3O10 + H 496.1931, found
496.1929. Anal.(C22H29N3O10·1.5H2O) C, H, N.
2-[4-((2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-{[(1S)-1-
(h yd r oxym et h yl)-3-m et h ylb u t yl]a m in o}-3-oxop r op yl)-
p h en oxy]m a lon ic a cid (106) was prepared by the general
procedure described for the preparation of 30 from 28b, using
(S)-leucinol as the amine component: 1H NMR (DMSO-d6) δ
7.99 (d, 1 H), 7.43 (d, 1 H), 7.11 (d, 2 H), 6.78 (d, 2 H), 5.25 (s,
1 H), 4.35 (m, 1 H), 7.72 (m, 1 H), 3.25 (dd, 1 H), 3.12 (dd, 1
H), 2.87 (dd, 1 H), 2.65 (dd, 1 H), 2.31 (m, 4 H), 1.52 (m, 1 H),
1.26 (m, 2 H), 0.82 (q, 6 H); MS (FAB) m/z (rel intensity) 483
(MH+, 91), 484 (22), 483 (91), 139 (25), 123 (18), 118 (99), 105
(17), 103 (15), 91 (18), 86 (16), 55 (15); HRMS (FAB) calcd for
2-(4-{(2S)-2-[(3-Car boxypr opan oyl)am in o]-3-[(4-h ydr oxy-
p h en et h yl)a m in o]-3-oxop r op yl}p h en oxy)m a lon ic a cid
(97) was prepared by the general procedure described for the
preparation of 30 from 28b: 1H NMR (DMSO) δ 8.06 (d, 1 H),
7.90 (t, 1 H), 7.09 (d, 2 H), 6.95 (d, 2 H), 6.79 (d, 2 H), 6.64 (d,
2 H), 5.27 (s, 1 H), 4.31 (m, 1 H), 3.15 (m, 2 H), 2.85 (dd, 1 H),
2.63 (m, 1 H), 2.52 (m, 2 H), 2.33 (m, 4 H); MS (ES-) 501;
HRMS (FAB) calcd for C24H26N2O10 + H 503.1665; found
503.1656.
2-(4-{(2S)-3-[(4-Car boxyben zyl)am in o]-2-[(3-car boxypr o-
p a n oyl)a m in o]-3-oxop r op yl}p h en oxy)m a lon ic a cid (98)
was prepared by the general procedure described for the
preparation of 30 from 28b: 1H NMR (DMSO) δ 8.49 (t, 1 H),
8.20 (d, 1 H), 7.85 (d, 2 H), 7.27 (d, 2 H), 7.13 (d, 2 H), 6.80 (d,
2 H), 5.28 (s, 1 H), 4.45 (m, 1 H), 4.31 (m, 2 H), 2.95 (dd, 1 H),
2.71 (dd, 1 H), 2.34 (m, 4 H); MS (FAB) m/z (rel intensity) 517
(MH+, 39), 517 (39), 391 (76), 149 (99), 113 (30), 71 (39), 69
(37), 57 (75), 55 (49), 43 (48), 41 (37); HRMS (FAB) calcd for
C24H24N2O11 + H 517.1458; found 517.1451. Anal. (C24H24N2O11·
0.64H2O) C, H; N: calcd, 5.31; found, 4.82.
2-[4-((2S)-2-[(4-Hyd r oxy-4-oxobu ta n oyl)a m in o]-3-oxo-
3-{[4-(t r iflu or om et h yl)b en zyl]a m in o}p r op yl)p h en oxy]-
m a lon ic a cid (99) was prepared by the general procedure
described for the preparation of 30 from 28b: 1H NMR
(DMSO) δ 8.50 (t, 1 H), 8.18 (d, 1 H), 7.62 (d, 2 H), 7.31 (d, 2
H), 7.12 (d, 2 H), 6.80 (d, 2 H), 5.27 (s, 1 H), 4.43 (m, 1 H),
7.32 (d, 2 H), 3.91 (dd, 1 H), 3.71 (dd, 1 H), 2.33 (m, 4 H); MS
(ES-) 539. Anal. (C24H23F3N2O9·0.62H2O) C, H, N.
2-(4-{(2S)-3-[(1,3-Ben zod ioxol-5-ylm eth yl)a m in o]-2-[(3-
c a r b o x y p r o p a n o y l)a m i n o ]-3-o x o p r o p y l}p h e n o x y )-
m a lon ic a cid (100) was prepared by the general procedure
described for the preparation of 30 from 28b: 1H NMR (DMSO)
δ 8.32 (t, 1 H), 8.11 (d, 1 H), 7.10 (d, 2 H), 6.78 (m, 4 H), 5.59
(d, 1 H), 5.95 (s, 2 H), 5.23 (s, 1 H), 4.40 (m, 1 H), 4.14 (d, 2
H), 3.92 (dd, 1 H), 2.70 (m, 1 H), 2.30 (m, 4 H); MS (ES-) 515.
Anal.(C24H24N2O11·2.3H2O) C, H, N.
2-(4-{(2S)-2-[(3-Ca r boxyp r op a n oyl)a m in o]-3-oxo-3-[(2-
ph en oxyeth yl)am in o]pr opyl}ph en oxy)m alon ic acid (101)
was prepared by the general procedure described for the
preparation of 30 from 28b: 1H NMR (DMSO) δ 8.15 (t, 1 H),
8.09 (d, 1 H), 7.27 (t, 2 H), 7.10 (d, 2 H), 6.92 (m, 3 H), 7.76 (d,
2 H), 5.23 (s, 1 H), 4.40 (m, 1 H), 3.90 (t, 2 H), 2.87 (dd, 1 H),
2.65 (dd, 1 H), 2.30 (m, 4 H); MS (FAB) m/z (rel intensity) 503
(MH+, 13), 392 (18), 391 (62), 149 (99), 113 (30), 71 (33), 69
(18), 57 (49), 55 (22), 43 (30), 41 (20); HRMS (FAB) calcd for
C24H26N2O10 + H 503.1665, found 503.1656. Anal. (C24H26N2O10)
C; H: calcd, 5.22; found, 5.79; N: calcd, 5.57; found, 4.96.
2-[4-((2S)-2-[(3-Ca r boxyp r op a n oyl)a m in o]-3-oxo-3-{[2-
(1-piper idin yl)eth yl]am in o}pr opyl)ph en oxy]m alon ic acid
(102) was prepared by the general procedure described for the
preparation of 30 from 28a : 1H NMR (DMSO) δ 1.47 (brs, 4
H), 1.66 (brs, 4 H), 2.33 (brs, 4 H), 2.76 (m, 4 H), 3.05 (brs, 4
H), 4.30 (m, 1 H), 5.04 (s, 1 H), 6.64 (d, 2 H), 7.01 (d, 2 H),
8.02 (m, 1 H), 8.16 (m, 1 H)(3-CO2H absent); MS (FAB) m/z
(rel intensity) 494 (MH+, 96), 495 (29), 494 (96), 450 (67), 392
(37), 133 (32), 98 (99), 71 (27), 57 (39), 45 (34), 43 (29). Anal.
(C23H31N3O9·1.42H2O) C, H, N.
2-[4-((2S)-2-[(3-Ca r boxypr op a n oyl)a m in o]-3-{[3-(4-m or -
p h olin yl)p r op yl]a m in o}-3-oxop r op yl)p h en oxy]m a lon ic
a cid (103) was prepared by the general procedure described
for the preparation of 30 from 28a : 1H NMR (DMSO) δ 2.32
(m, 6 H), 2.50-2.80 (m, 6 H), 2.97 (m, 4 H), 3.76 (m, 4 H),
4.31 (m, 1 H), 5.10 (s, 1 H), 6.68 (d, 2 H), 7.00 (d, 2 H), 7.79
(m, 1 H), 8.05 (m, 1 H) (3-CO2H absent); MS (FAB) m/z (rel
intensity) 510 (MH+, 99), 511 (21), 510 (99), 466 (34), 463 (30),
308 (29), 241 (24), 177 (23), 100 (40), 57 (23), 39 (21). Anal.
(C23H31N3O10·2.0H2O) C, H, N.
C
22H30N2O10 + H 483.1978, found 483.199. Anal. (C22H30N2O10
·
1.4H2O) C, H, N.
2-{4-[(2S)-2-({(2S)-4-Ca r boxy-2-[(3-ca r boxyp r op a n oyl)-
a m in o]bu ta n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic a cid (107) was prepared by procedures
analogous to those described for the preparation of 34 from
1
12a (Scheme 5): H NMR (DMSO) δ 0.82 (t, 3 H), 1.20 (m, 3
H), 1.32 (m, 3 H), 1.55-1.90 (m, 2H), 2.14 (t, 2 H), 2.38 (m, 4
H), 2.72 (m, 2 H), 2.92 (m, 4 H), 4.11 (m, 1 H), 4.30 (m, 1 H),
5.21 (s, 1 H), 6.77 (d, 2 H), 7.67 (t, 1 H), 7.77 (d, 1 H), 8.08 (d,
1 H) (4-CO2H absent); MS (FAB) m/z (rel intensity) 582 (MH+,
51), 582 (51), 238 (41), 133 (42), 102 (81), 102 (99), 88 (92), 84
(64), 43 (39), 39 (75), 23 (78). Anal. (C26H35N3O12·1.37H2O) C,
H, N.
2-{4-[(2S)-2-({(2S)-2-[(ter t-b u t oxyca r b on yl)a m in o]-4-
ca r boxybu ta n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic a cid (108) was prepared by procedures
analogous to those described for the preparation of 32 from
12a (Scheme 5): 1H NMR (DMSO) δ 0.81 (t, 3 H), 1.18 (m, 15
H), 1.71 (m, 2 H), 2.12 (t, 2 H), 2.96-3.10 (m, 4 H), 3.82 (m, 1
H), 4.38 (m, 1 H), 5.19 (s, 1 H), 6.76 (d, 2 H), 6.96 (d, 1 H),
7.08 (d, 2 H), 7.77 (d, 1 H), 7.84 (brt, 1 H) (3-CO2H absent);
MS (FAB) m/z (rel intensity) 582 (MH+, 2), 133 (19), 102 (25),
88 (54), 84 (25), 57 (99), 43 (24), 41 (43), 39 (16), 29 (40), 23
(52). Anal. (C27H39N3O11·1.22H2O) C, H, N.
2-{4-[(2S)-2-[((2S)-2-{[(Ben zyloxy)ca r b on yl]a m in o}-3-
ca r boxyp r op a n oyl)a m in o]-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic a cid (109) was prepared from 12a by
procedures analogous to those described for the preparation
of 32 (Scheme 5), except that Cbz-Asp(OBn)OSu was used in
place of Boc-Asp(OBn)OSu and saponification with LiOH was
used in the final step instead of hydrogenation: 1H NMR
(DMSO) δ 8.10 (d, 1 H), 7.80 (t, 1 H), 7.45 (d, 1 H), 7.31 (m, 5
H), 7.00 (d, 2 H), 6.78 (d, 2 H), 5.24 (s, 1 H), 5.00 (s, 2 H), 4.32
(m, 1 H), 2.80-3.00 (m, 3 H), 2.55-2.70 (m, 3 H), 1.10-1.35
(m, 6 H), 0.82 (t, 3 H); MS (FAB) m/z (rel intensity) 602 (MH+,
37), 602 (37), 392 (17), 391 (54), 149 (63), 113 (18), 91 (99), 74
(34), 71 (22), 57 (29), 43 (22); HRMS (FAB) calcd for C29H35N3O11
+ H 602.2349, found 602.2363; Anal. (C29H35N3O11·H2O) C, H,
N.
2-{4-[(2S )-2-({(2R )-3-(4-B e n zo y lp h e n y l)-2-[(3-c a r -
b o x y p r o p a n o y l)a m i n o ]p r o p a n o y l}a m i n o )-3-o x o -3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (110) was
prepared by procedures identical to those described for the
preparation of 38 from 12b, starting with D-Boc-Bpa-OH: 1H
NMR (DMSO-d6) δ 8.38 (d, 1 H), 8.10 (d, 1 H), 7.90 (t, 1 H),
7.67 (m, 3 H), 7.55 (m, 4 H), 7.25 (d, 2 H), 7.25 (d, 2 H), 7.79
2-[4-((2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-{[3-(1H -
im id a zol-1-yl)p r op yl]a m in o}-3-oxop r op yl)p h en oxy]m a -
lon ic a cid (104) was prepared by the general procedure
described for the preparation of 30 from 28a : 1H NMR (DMSO/
DCl) δ 0.93 (t, 2 H), 1.80-1.93 (m, 3 H), 2.28 (m, 3 H), 3.03

620 J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3
Larsen et al.
(d, 2 H), 5.21 (s, 1 H), 4.52 (m, 1 H), 4.38 (m, 1 H), 3.00 (m, 2
H), 2.75-2.90 (m, 2 H), 2.60 (dd, 2 H), 2.27 (m, 4 H), 1.21 (m,
6 H), 0.83 (t, 3 H); MS (FAB) m/z (rel intensity) 704 (MH+,
99), 705 (42), 704 (99), 353 (20), 238 (35), 224 (70), 219 (27),
194 (19), 107 (28), 105 (34), 88 (49); HRMS (FAB) calcd for
C37H41N3O11 + H 704.2819, found 704.2822. Anal. Calcd for
2-{4-[(2S)-2-{[(2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-(4-
m eth oxyph en yl)pr opan oyl]am in o}-3-oxo-3-(pen tylam in o)-
p r op yl]p h en oxy}m a lon ic a cid (116) was prepared by pro-
cedures analogous to those described for the preparation of
37 from 12b (Scheme 7): 1H NMR (DMSO-d6) δ 7.85 (m, 2 H),
7.09 (m, 4 H), 6.78 (m, 5 H), 5.22 (s, 1 H), 4.40 (m, 1 H), 4.02
(m, 1 H), 3.68 (s, 3 H), 2.97 (m, 2 H), 3.90-3.70 (m, 3 H), 2.60
(m, 1 H), 1.34-1.12 (m, 15 H), 0.82 (t, 3 H); MS (FAB) m/z
(rel intensity) 630 (MH+, 11), 574 (24), 238 (29), 194 (31), 177
(34), 161 (29), 150 (99), 136 (24), 121 (65), 88 (64), 57 (87);
HRMS (FAB) calcd for C32H43N3O10 + H 630.3026, found
630.3015. Anal. (C32H43N3O10·1.64H2O) C, H, N.
2-{4-[(2S)-2-({(2S)-2-[(ter t-Bu t oxyca r b on yl)a m in o]-3-
p h en ylp r op a n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic a cid (117) was prepared by procedures
analogous to those described for the preparation of 37 from
12b (Scheme 7): 1H NMR (DMSO-d6) δ 7.87 (m, 2 H), 7.17
(m, 5 H), 6.90 (d, 1 H), 6.80 (d, 2 H), 5.22 (s, 1 H), 4.41 (m, 1
H), 4.10 (m, 1 H), 2.97 (m, 2 H), 2.83 (m, 2 H), 2.70-2.50 (m,
2 H), 1.34-1.12 (m, 15 H), 0.82 (t, J ) 3 Hz, H); MS (FAB)
m/z (rel intensity) 600 (MH+, 27), 600 (27), 544 (33), 238 (22),
136 (22), 133 (22), 120 (99), 88 (61), 57 (87), 43 (18), 41 (20);
HRMS (FAB) calcd for C31H41N3O9 + H 600.2921, found
600.2923. Anal. (C31H41N3O9·0.96H2O) C, H, N.
2-{4-[(2S )-2-({(2S )-2-[(t er t -Bu t oxyca r b on yl)a m in o]-
p r o p a n o y l}a m i n o )-3-o x o -3-(p e n t y la m i n o )p r o p y l]-
p h en oxy}m a lon ic a cid (118) was prepared by procedures
analogous to those described for the preparation of 37 from
12b (Scheme 7): 1H NMR (DMSO-d6) δ 7.80 (m, 1 H), 7.69 (d,
1 H), 7.08 (d, 2 H), 6.95 (d, 1 H), 6.77 (d, 2 H), 5.22 (s, 1 H),
4.35 (m, 1 H), 3.80 (m, 1 H), 2.95 (m, 2 H), 2.95-2.85 (m, 1
H), 2.75 (m, 1 H), 1.35-1.15 (m, 15 H), 1.05 (d, 3 H), 0.82 (t,
3 H); MS (FAB) m/z (rel intensity) 524 (MH+, 13), 468 (39),
238 (25), 136 (21), 133 (20), 88 (99), 86 (19), 57 (71), 44 (58),
41 (19), 29 (18); HRMS (FAB) calcd for C25H37N3O9 + H
524.2607, found 524.2612. Anal. Calcd for C25H37N3O9·2.22H2O)
C, H, N.
5-[(2S )-2-({(2R )-2-[(t er t -Bu t oxyca r b on yl)a m in o]-3-
p h en ylp r op a n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
2-(ca r boxym et h oxy)ben zoic a cid (119) was prepared by
procedures identical to those described for the preparation of
69 from 55, using N-Boc-D-Phe-OH (Scheme 13): 1H NMR
(DMSO-d6) δ 8.30 (d, J ) 8 Hz, 1 H), 7.84 (bt, J ) 6 Hz, 1 H),
7.58 (bs, 1 H), 7.27 (bd, J ) 8 Hz, 1 H), 7.15 (m, 5 H), 6.88 (d,
J ) 9 Hz, 1 H), 6.79 (d, J ) 8 Hz, 1 H), 4.66 (s, 2 H), 4.38 (m,
1 H), 4.11 (m, 1 H), 2.5-3.1 (m, 6 H), 1.1-1.4 (m, 6 H), 1.27
(s, 9 H), 0.83 (t, J ) 7 Hz, 3 H); MS (ESI-) for C31H41N3O9
m/z 598.4 (M - H)-; HRMS (FAB) calcd for C31H41N3O9 + H
600.2921, found 600.2930.
C
37H41N3O11: C, 63.15; H, 5.87; N, 5.97. Found: C, 63.69; H,
6.36; N, 5.24.
2-{4-[(2S )-2-({(2S )-3-[4-(B e n zy lo x y )p h e n y l]-2-[(3-
ca r b oxyp r op a n oyl)a m in o]p r op a n oyl}a m in o)-3-oxo-3-
(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (111) was
prepared by procedures analogous to those described for the
preparation of 38 from 12b (Scheme 7): 1H NMR (DMSO-d6)
δ 8.05 (d, 1 H), 7.95 (d, 1 H), 7.66 (t, 1 H), 7.36 (m, 5 H), 7.09
(t, 4 H), 6.82 (dd, 4 H), 5.25 (s, 1 H), 5.02 (s, 2 H), 4.34 (m, 2
H), 2.97 (m, 2 H), 2.95-2.90 (m, 2 H), 2.90 (dd, 1 H), 2.61 (dd,
1 H), 2.30 (m, 4 H), 1.33-1.13 (m, 6 H), 0.82 (t, 3 H); MS (FAB)
m/z (rel intensity) 706 (MH+, 36), 707 (15), 706 (36), 353 (15),
238 (13), 226 (28), 91 (99), 88 (16), 57 (20), 55 (15), 43 (20);
HRMS (FAB) calcd for C37H43N3O11 + H 706.2975, found
706.2986. Anal.(C37H43N3O11·0.80H2O) C, H, N.
2-{4-[(2S)-2-[((2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-
{4-[(2,6-d ich lor oben zyl)oxy]p h en yl}p r op a n oyl)a m in o]-3-
oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (112)
was prepared by procedures analogous to those described for
the preparation of 38 from 12b (Scheme 7): 1H NMR (DMSO-
d6) δ 8.10 (d, 1 H), 7.95 (d, 1 H), 7.67 (t, 1 H), 7.54 (m, 2 H),
7.45 (dd, 1 H), 7.11 (m, 4 H), 6.91 (d, 2 H), 6.81 (d, 2 H), 5.26
(s, 1 H), 5.15 (s, 2 H), 4.35 (m, 2 H), 2.98 (m, 2 H), 2.85 (m, 2
H), 2.73 (dd, 1 H), 2.62 (dd, 1 H), 2.33 (m, 4 H), 1.33-1.12 (m,
6 H), 0.81 (t, 3 H); MS (FAB) m/z (rel intensity) 774 (MH+,
99), 776 (70), 775 (53), 774 (99), 391 (97), 294 (48), 161 (54),
159 (80), 149 (63), 136 (39), 88 (46); HRMS (FAB) calcd for
C
37H41Cl2N3O11 + H 774.2196, found 774.2224. Anal. (C37H41
-
Cl2N3O11·0.36H2O) C, H, N.
2-{4-[(2S)-2-{[(2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-
(4-m e t h o x y p h e n y l)p r o p a n o y l]a m in o }-3-o x o -3-(p e n -
tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (113) was pre-
pared by procedures analogous to those described for the
preparation of 38 from 12b (Scheme 7): 1H NMR (DMSO-d6)
δ 8.02 (d, 1 H), 7.90 (d, 1 H), 7.64 (t, 1 H), 7.09 (m, 4 H), 6.78
(m, 4 H), 5.25 (s, 1 H), 4.35 (m, 2 H), 3.68 (s, 3 H), 2.98 (m, 2
H), 2.9-2.70 (m, 3 H), 2.60 (dd, 1 H), 2.30 (m, 4 H), 1.35-1.10
(m, 6 H), 0.82 (t, 3 H); MS (FAB) m/z (rel intensity) 630 (MH+,
81), 631 (28), 630 (81), 353 (25), 250 (25), 238 (23), 177 (30),
161 (28), 150 (99), 121 (44), 88 (39); HRMS (FAB) calcd for
C31H39N3O11 + H 630.2662, found 630.2661. Anal. (C31H39N3O11·
0.54H2O) C, H, N.
Assa ys for P TP Activity. PTP catalytic activities were
routinely measured as rates of hydrolysis of p-nitrophenyl
phosphate (pNPP) in a 96-well microtiter plate format. Sources
of the PTP enzymes used as well as details of the PTP assays
are described elsewhere.19 Inhibitors were added to PTP assay
mixtures as solutions in DMSO at 100 times the final
concentration. For determinations of inhibitor kinetics, plots
of V versus S at various concentrations of inhibitor were
generated and Ki values were computed using the direct linear
method of Cornish-Bowden (Enzpack3 software, Biosoft,
Cambridge, UK).
Mea su r em en t of Cellu la r In su lin Resp on se. For the
evaluation of PTP1B inhibitors as enhancers of insulin action,
we measured rates of uptake of 2-deoxyglucose by L6 myocytes
in the absence and presence of insulin at a concentration (10
nM) that supported half-maximal uptake.19 Data are expressed
as percent basal (unstimulated) in the absence of compound
and as percent insulin-stimulated, i.e.,
2-{4-[(2S)-2-({(2S)-2-[(3-Ca r b oxyp r op a n oyl)a m in o]-3-
p h en ylp r op a n oyl}a m in o)-3-oxo-3-(p en tyla m in o)p r op yl]-
p h en oxy}m a lon ic a cid (114) was prepared by procedures
analogous to those described for the preparation of 38 from
12b (Scheme 7): 1H NMR (DMSO-d6) δ 8.10 (d, 1 H), 7.96 (d,
1 H), 7.69 (t, 1 H), 7.15 (m, 7 H), 6.80 (d, 2 H), 5.26 (s, 1 H),
4.35 (m, 2 H), 2.92 (m, 4 H), 2.71 (m, 2 H), 2.80 (m, 4 H), 1.25
(m, 6 H), 0.82 (t, 3 H); MS (FAB) m/z (rel intensity) 600 (MH+,
35), 600 (35), 155 (22), 149 (50), 136 (20), 120 (99), 88 (27), 73
(32), 71 (23), 57 (34), 43 (26); HRMS (FAB) calcd for C30H37N3O10
+ H 600.2557, found 600.2579. Anal.(C30H37N3O10·0.51H2O) C,
H, N.
2-{4-[(2S)-2-[((2S)-2-[(ter t-Bu toxyca r bon yl)a m in o]-3-{4-
[(2,6-d ich lor ob en zyl)oxy]p h en yl}p r op a n oyl)a m in o]-3-
oxo-3-(p en tyla m in o)p r op yl]p h en oxy}m a lon ic a cid (115)
was prepared by procedures analogous to those described for
the preparation of 37 from 12b (Scheme 7): 1H NMR (DMSO-
d6) δ 7.87 (m, 2 H), 7.53 (m, 2 H), 7.46 (m, 1 H), 7.11 (d, 2 H),
6.91 (d, 2 H), 6.89 (m, 1 H), 6.80 (d, 2 H), 5.23 (s, 1 H), 5.15 (s,
2 H), 4.40 (m, 1 H), 4.05 (m, 1 H), 2.97 (m, 2 H), 2.78 (m, 3 H),
2.60 (m, 1 H), 1.35-1.14 (m, 15 H), 0.81 (t, 3 H); MS (FAB)
m/z (rel intensity) 774 (MH+, 8), 296 (28), 294 (41), 238 (39),
194 (31), 161 (52), 159 (81), 136 (31), 88 (56), 57 (99), 41 (24);
HRMS (FAB) calcd for C38H45Cl2N3O10 + H 774.2560, found
774.2557. Anal. (C38H45Cl2N3O10·0.92H2O) C, H, N.
[(uptake with insulin plus test cpd) -
(uptake without insulin plus test cpd)]/
[(uptake with insulin no test cpd) -
(uptake without insulin no test cpd)] × 100%
A value of g120% was scored as active.

Inhibitors of Protein Tyrosine Phosphatase 1B
J ournal of Medicinal Chemistry, 2002, Vol. 45, No. 3 621
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Ack n ow led gm en t. The authors thank Phil Burton
and Robert Conradi for the Caco-2 permeability analysis
of selected compounds in this work.
Su p p or tin g In for m a tion Ava ila ble: Crystallography
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