Design and synthesis of novel metalloproteinase inhibitors

Article abstract of DOI:10.1016/j.bmc.2006.03.032

A series of N-benzoyl 4-aminobutyric acid hydroxamate analogs were synthesized and evaluated as matrix metalloproteinase inhibitors. Synthetic work was focused on the chemical modification of the 4-aminobutyric acid part using easily available starting materials. As such, chemical modification was carried out using commercially available starting materials such as 4-aminobutyric acid, (+)- and (-)-malic acid, and d- and l-glutamic acid derivatives. Among the compounds tested, N-[4-(benzofuran-2-yl)benzoyl] 4-amino-4S-hydroxymethylbutyric acid hydroxamates derived from l-glutamic acid demonstrated more potent inhibitory activity against MMP-2 and MMP-9 compared with the corresponding 2S-hydroxy analogs or 3S-hydroxy analogs, respectively, which were derived from (-)-malic acid. Structure-activity relationship study is presented.

Full text of DOI:10.1016/j.bmc.2006.03.032

Bioorganic & Medicinal Chemistry 14 (2006) 5402–5422
Design and synthesis of novel metalloproteinase inhibitors
Shingo Nakatani,* Masahiro Ikura, Shingo Yamamoto, Yoshitaka Nishita,
Satoshi Itadani, Hiromu Habashita, Tsuneyuki Sugiura, Koji Ogawa, Hiroyuki Ohno,
Kanji Takahashi, Hisao Nakai and Masaaki Toda
Minase Research Institute, Ono Pharmaceutical Co., Ltd, 3-1-1 Sakurai, Shimamoto, Mishima, Osaka 618-8585, Japan
Received 3 March 2006; revised 16 March 2006; accepted 17 March 2006
Available online 18 April 2006
Abstract—A series of N-benzoyl 4-aminobutyric acid hydroxamate analogs were synthesized and evaluated as matrix metallopro-
teinase inhibitors. Synthetic work was focused on the chemical modification of the 4-aminobutyric acid part using easily available
starting materials. As such, chemical modification was carried out using commercially available starting materials such as 4-amino-
butyric acid, (+)- and (ꢀ)-malic acid, and D- and L-glutamic acid derivatives. Among the compounds tested, N-[4-(benzofuran-2-
yl)benzoyl] 4-amino-4S-hydroxymethylbutyric acid hydroxamates derived from L-glutamic acid demonstrated more potent
inhibitory activity against MMP-2 and MMP-9 compared with the corresponding 2S-hydroxy analogs or 3S-hydroxy analogs,
respectively, which were derived from (ꢀ)-malic acid. Structure–activity relationship study is presented.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
angiogenesis and tumor metastasis; carcinogenesis and
tumor growth, respectively.3–5 Accordingly inhibitors
of the gelatinases may have therapeutic potential for
angiogenesis and/or tumor metastasis.
Matrix metalloproteinases (MMPs) are a family of zinc-
containing endoproteinases that have been traditionally
characterized by their collective ability to degrade all
components of the extracellular matrix. These enzymes
are postulated to regulate the homeostasis of a variety
of tissues under the control of tissue inhibitor of
metalloproteinases (TIMPs), which bind to and inhibit
the activity of MMPs. Accordingly, an imbalance be-
tween MMPs and TIMPs can lead to a variety of path-
ological states, such as metastasis of cancer, or diseases
including, rheumatoid arthritis and multiple sclerosis.
At least 20 members of this enzyme family, which dem-
onstrate significant sequence homology, have been
reported.1,2 They can be divided into collagenases
(MMP-1, -8, -13, and -18), gelatinases (MMP-2 and
-9), stromelysins (MMP-3, -10, and -11), and mem-
brane-type MMPs (MMP-14, -15, -16, and -17). For
more than 30 years MMPs have been seen as promising
targets for the treatment of the above-mentioned diseas-
es because collagenase (MMP-1), gelatinases (MMP-2
and -9), and stromelysin-I (MMP-3) have been shown
to play a key role in cancer invasion and metastasis;
A large number of succinyl hydroxamates and sulfon-
amide hydroxamates have been reported as MMP inhib-
itors.6 In our previous paper, we reported on the
discovery of N-benzoyl 4-aminobutyric acid hydroxa-
mate 1 (Table 1) as a new chemical lead for an MMP
inhibitor (MMPI) by the fragment-based lead genera-
tion procedure.7 Here, we report on the further optimi-
zation of 1 and on identification of novel MMPIs
derived from malic acid and glutamic acid.
2. Chemistry
The compounds listed in Tables 1–5 were synthesized as
described in Schemes 1–11. Compound 1 was prepared
as described in Scheme 1. N-Benzoylation of 4-amino-
butyric acid with p-toluoyl chloride 22 under alkaline
condition afforded 23. Condensation of 23 with a pro-
tected hydroxylamine hydrochloride led to 24, catalytic
hydrogenation of which provided the hydroxamate 1.
Synthesis of 2 is outlined in Scheme 2. Suzuki coupling
of 25 with benzofuran-2-boronic acid in the presence of
a palladium catalyst produced 26. Alkaline hydrolysis of
Keywords: MMP; Matrix metalloproteinase inhibitor; Hydroxamate
inhibitor; 4-Aminobutyric acid hydroxamate.
*
Corresponding author. E-mail: s.nakatani@ono.co.jp
0968-0896/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2006.03.032

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
Table 1. Effect of the p-substituent of the N-benzoyl residue on the activity profiles
5403
O
H
N
HO
N
H
O
R
a,d
IC50 (lM)
Compound
R
MMP-1
59%b
MMP-2
18
MMP-9
>100
MMP-3
1
2
–Me
NTc
O
53%b
0.0029
0.054
1.8
3
4
>100
9.9
0.038
0.047
0.012
NT
2.9
16
O
CH2OMe
a Concentration required for 50% inhibition of enzyme activity.
b Inhibition percentage at 100 lM.
c Not tested.
d IC50 values were determined in a single experimental run in duplicate.
Table 2. Effect of the C2-substitution on the activity profiles
R
O
H
N
HO
N
H
O
O
a,c
IC50 (lM)
Compound
R
MMP-1
53%b
MMP-2
0.0029
MMP-9
0.054
MMP-3
1.8
2
5
H
56%b
44%b
0.0033
0.0069
0.053
NT
1.3
8.2
OH
OH
6
7
8
46%b
35
0.0036
0.78
0.024
NT
0.74
OBOM
OBOM
CH2
44%b
Ph
n
9
10
11
n = 1
n = 2
n = 3
32
>100
36%b
0.035
0.021
0.017
0.057
NT
0.043
0.16
0.83
0.25
BOM, benzyloxymethyl.
a Concentration required for 50% inhibition of enzyme activity.
b Inhibition percentage at 100 lM.
c IC50 values were determined in a single experimental run in duplicate.
the ester 26 resulted in 27. Condensation of the carbox-
ylic acid 27 with 4-aminobutyric acid ethyl ester in the
presence of EDC afforded 28. Alkaline hydrolysis of
28 produced 29, condensation of which with a protected
hydroxylamine in the presence of EDC, followed by
acidic deprotection, gave compound 2.
a protected hydroxylamine in the presence of EDC, fol-
lowed by deprotection, led to compound 3.
Compound 4 was prepared from 35, which was obtained
by palladium-catalyzed coupling reaction of methyl 4-
iodobenzoate 33 with 3-methoxy-1-propyne, followed
by alkaline hydrolysis, as described in Scheme 4.
Condensation of 35 with 4-aminobutyric acid ethyl
ester produced 36, alkaline hydrolysis of which
provided 37. Condensation of 37 with a protected
hydroxylamine, followed by acidic deprotection, affor-
ded compound 4.
Compound 3 was prepared as described in Scheme 3.
Condensation of a carboxylic acid 30 with 4-aminobu-
tyric acid ethyl ester in the presence of EDC afforded
31, alkaline hydrolysis of which produced the corre-
sponding carboxylic acid 32. Condensation of 32 with

5404
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
Table 3. Effect of the C3-substitution on the activity profiles
Table 5. Effect of the C4-substitution of another N-benzoyl analogs on
the activity profiles
O
H
N
R
O
H
N
HO
N
H
O
R
HO
N
H
O
O
o
a,b
IC50 (lM)
a,c
IC50 (lM)
Compound
R
Compound
R
MMP-1 MMP-2 MMP-9 MMP-3
MMP-1 MMP-2 MMP-9 MMP-3
53%b
38%b
0.0029
0.0050
0.054
0.093
1.8
1.5
4
-H
OH
9.9
2.1
0.047
0.022
NT
NT
16
4.7
2
H
OH
18
12
OH
OH
13
14
15
>100
46%b
>100
0.026
0.025
0.026
NT
0.16
NT
10
19
20
21
4.5
1.1
1.7
0.049
0.0088
0.016
NT
NT
NT
11
2.0
3.1
OMOM
OMOM
OMOM
OMOM
1.5
7.7
MOM, methoxymethyl.
a Concentration required for 50% inhibition of enzyme activity.
b Inhibition percentage at 100 lM.
MOM, methoxymethyl.
a Concentration required for 50% inhibition of enzyme activity.
b IC50 values were determined in a single experimental run in duplicate.
c IC50 values were determined in a single experimental run in duplicate.
which were converted to their corresponding hydroxa-
mates 7 and 8, respectively, by the usual procedures.
Table 4. Effect of the C4-substitution on the activity profiles
R
O
H
N
Synthesis of 9 from 49, which was prepared by N-ben-
zoylation of 4-aminobutyric acid ethyl ester, is outlined
in Scheme 6. C2-Alkylation of 49 under conventional
reaction conditions yielded 50, which was converted to
51 by the palladium-catalyzed coupling reaction with
benzofuran-2-boronic acid. Alkaline hydrolysis of 51
provided 52, which was converted to the hydroxamate
9 by the usual procedure.
HO
N
H
O
O
a,c
IC50 (lM)
Compound
R
H
MMP-1 MMP-2 MMP-9 MMP-3
2
16
17
53%b
2.6
0.0029
0.0019
0.054
0.012
1.8
Synthesis of 10 is outlined in Scheme 7. Alkylation of 53
with bromoacetonitrile resulted in 54, which was re-
duced to an amino ester 55. N-Acylation of 55 with
the acid chloride 43 produced 56, alkaline hydrolysis
of which afforded 57. Compound 57 was converted to
the corresponding hydroxamate 10 in the usual manner.
OH
0.54
0.23
OMOM
1.5
0.00073 0.0077
MOM, methoxymethyl.
a Concentration required for 50% inhibition of enzyme activity.
b Inhibition percentage at 100 lM.
c IC50 values were determined in a single experimental run in duplicate.
Synthesis of 11 is described in Scheme 8. C2-Alkylation
of 49 with 1-bromo-3-phenyl-2-propene gave 58. Palla-
dium-catalyzed Suzuki coupling of 58 with the benzofu-
ran-2-yl boronic acid afforded 59, and catalytic
hydrogenation of 59 produced 60. Then compound 60
was converted to the hydroxamate 11 according to the
procedure described above.
Synthesis of optically active analogs 5–8 from the malic
acids possessing the corresponding absolute configura-
tions is outlined in Scheme 5. Reduction of the carbox-
ylic acid of 38a,b with diborane produced alcohols
39a,b, respectively, tosylation of which resulted in
40a,b, respectively. The tosylates 40a,b were substituted
by sodium azide to produce 41a,b, respectively. Acidic
deprotection of 41a,b in the presence of methanol led
to 42a,b, respectively. Catalytic hydrogenation of
42a,b, followed by N-acylation with an acid chloride
43 prepared from the corresponding carboxylic acid,
gave 44a,b, respectively. Alkaline hydrolysis of 44a,b
gave 45a,b, respectively, which were converted to the
corresponding hydroxamates 5 and 6, respectively, in
the usual manner. O-Alkylation of 44a,b with a benzyl-
oxymethylchloride (BOMCl) resulted in the formation
of 46a,b, respectively. Alkaline hydrolysis of 46a,b gave
the corresponding carboxylic acids 47a,b, respectively,
Synthesis of 12–15 is outlined in Scheme 9. The selective
reduction of optically active malic acid methyl esters
62a,b yielded 63a,b, respectively.8 Tosylation of 63a,b
afforded 64a,b, respectively, substitution of which with
sodium azide produced 65a,b, respectively. Catalytic
hydrogenation of the azides 65a,b, followed by N-acyla-
tion of the amino function thus formed, led to 66a,b,
respectively. Alkaline hydrolysis of 66a,b, followed by
formation of the hydroxamates 12 and 13, was carried
out according to the usual procedures, as described
above. O-Alkylation of 66a,b with methoxymethyl chlo-
ride (MOMCl) provided 68a,b, respectively, while alka-
line hydrolysis of 68a,b afforded 69a,b, respectively.

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5405
O
O
O
H
N
a
b
Cl
HO2C
N
H
RO
c
N
H
O
22
23
24 R = Bzl
1
R = H
i
Scheme 1. Synthesis of 1. Reagents: (a) 4-aminobutyric acid, NaOH aq, THF; (b) HClÆNH2OBzl, EDC, HOBt, Pr2NEt, DMF; (c) H2, Pd–C,
MeOH.
HO2C
EtO2C
EtO2C
a
b
c
O
O
I
25
26
27
O
R
O
N
H
O
28 R = OEt
29 R = OH
d
e, f
2
R = NHOH
Scheme 2. Synthesis of 2. Reagents: (a) benzofuran-2-boronic acid, PdCl2(PPh3)2, Et3N, DMF; (b) NaOH aq, dioxane; (c) 4-aminobutyric acid ethyl
ester hydrochloride, EDC, HOBt, Et3N, DMF; (d) NaOH aq, THF; (e) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (f) HCl,
MeOH.
O
R
HO2C
N
H
a
O
O
O
30
31
R = OEt
b
32 R = OH
c, d
3
R = NHOH
Scheme 3. Synthesis of 3. Reagents: (a) 4-aminobutyric acid ethyl ester hydrochloride, EDC, HOBt, Et3N, DMF; (b) NaOH aq, THF; (c) O-(2-
methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (d) HCl, MeOH.
MeO2C
MeO2C
HO2C
a
b
I
O
O
33
34
35
O
R
N
H
c
O
O
36
37
4
R = OEt
R = OH
d
e, f
R = NHOH
Scheme 4. Synthesis of 4. Reagents: (a) 3-methoxy-1-propyne, PdCl2(PPh3)2, Et3N, DMF; (b) NaOH aq, DMF–MeOH; (c) 4-aminobutyric acid
ethyl ester hydrochloride, EDC, HOBt, Et3N, DMF; (d) NaOH aq, THF; (e) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF;
(f) HCl, MeOH.

5406
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
OH
*
O
*
O
d
a
O
O
CO2H
MeO2C
N3
*
R1
O
O
42a : * = (S)
42b : * = (R)
38a : * = (S)
38b : * = (R)
39a : * = (S),R1 = OH
39b : * = (R),R1 = OH
b
c
40a : * = (S),R1 = OTs
40b : * = (R),R1 = OTs
41a : * = (S),R1 = N3
41b : * = (R),R1 = N3
ClOC
e
O
27
43
OR3
O
R2
N
H
*
f
O
O
j
44a : * = (S),R2 = OMe, R3 = H
44b : * = (R),R2 = OMe, R3 = H
46a : * = (S), R2 = OMe, R3 = BOM
46b : * = (R), R2 = OMe, R3 = BOM
g
g
47a : * = (S), R2 = OH, R3 = BOM
47b : * = (R), R2 = OH, R3 = BOM
45a : * = (S),R2 = OH, R3 = H
45b : * = (R),R2 = OH, R3 = H
h, i
h, i
5 : * = (S), R2 = NHOH, R3 = H
6 : * = (R), R2 = NHOH, R3 = H
7 : * = (S),R2 = NHOH, R3 = BOM
8 : * = (R), R2 = NHOH, R3 = BOM
Scheme 5. Synthesis of 5–8. Reagents: (a) BH3–THF, THF; (b) TsCl, pyridine; (c) NaN3, DMF; (d) TsOH, MeOH; (e) SOCl2; (f) i—H2, Pd–C, 4 N
HCl/MeOH, MeOH; ii—Et3N, CH2Cl2; (g) NaOH aq, THF–MeOH; (h) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (i) HCl,
i
MeOH; (j) BOMCl, Pr2NEt, CH2Cl2.
O
O
HO2C
a
b
EtO2C
N
H
EtO2C
N
H
I
I
I
48
49
50
O
R
c
N
H
O
O
51 R = OEt
52 R = OH
d
e, f
9
R = NHOH
Scheme 6. Synthesis of 9. Reagents: (a) 4-aminobutyric acid ethyl ester hydrochloride, EDC, HOBt, Et3N, DMF; (b) LiHMDS, BnBr, THF; (c)
benzofuran-2-boronic acid, PdCl2(PPh3)2, Et3N, DMF; (d) NaOH aq, THF–MeOH; (e) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt,
DMF; (f) HCl, MeOH.
Formation of the hydroxamates 14 and 15 was carried
out according to the usual procedures, as described
above.
Synthesis of 16 and 17 is described in Scheme 10. Com-
pound 71, which was prepared by N-acylation of c-
methyl L-glutamate 70 with 43, was converted to 72 by

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5407
a
c
EtO2C
b
CN
.
NH2 HCl
EtO2C
EtO2C
53
54
55
O
R
N
H
O
O
56 R = OEt
57 R = OH
d
e, f
10 R = NHOH
Scheme 7. Synthesis of 10. Reagents: (a) LDA, bromoacetonitrile, THF; (b) H2, Pt2O, 4 N HCl/EtOAc, MeOH; (c) 43, Et3N, CH2Cl2; (d) NaOH aq,
THF; (e) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (f) HCl, MeOH.
O
a
b
c
O
49
EtO2C
N
H
EtO2C
N
H
O
I
58
59
O
R
N
H
O
O
60 R = OEt
61 R = OH
d
e, f
11 R = NHOH
Scheme 8. Synthesis of 11. Reagents: (a) LiHMDS, 1-bromo-3-phenyl-2-propene, THF; (b) benzofuran-2-boronic acid, PdCl2(PPh3)2, Et3N, DMF;
(c) H2, Pd–C, MeOH–DMF; (d) NaOH aq, THF–MeOH; (e) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (f) HCl, MeOH.
hydroboration with diborane. Alkaline hydrolysis of 72,
followed by formation of the hydroxamate, was carried
out according to the usual procedures to produce 16. O-
Alkylation of 72 with MOMCl gave 74, alkaline hydro-
lysis of which afforded 75. The hydroxamate 17 was ob-
tained from the carboxylic acid 75 in the usual manner.
chloride provided 77a,b, respectively. Hydride reduction
of the corresponding activated esters of 77a,b gave
78a,b, respectively. Palladium-catalyzed coupling reac-
tion of 78a,b with an alkyne provided 79a,b, respective-
ly. Alkaline hydrolysis of 79a,b, followed by
hydroxamate formation by the usual procedures, result-
ed in 18 and 19, respectively. O-Alkylation of 79a,b with
MOMCl provided 81a,b, respectively. Alkaline hydroly-
sis of 81a,b, followed by hydroxamate formation by the
usual procedures, led to 20 and 21, respectively.
Synthesis of optically active analogs 18–21 is outlined in
Scheme 11. N-Acylation of optically active glutamic
acid c-methyl esters 70 and 76 with 4-iodobenzoyl

5408
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
OH
*
OH
d, e
a
CO2Me
CO2Me
R1
MeO2C
*
62a : * = (S)
62b : * = (R)
63a : * = (S),R1 = OH
63b : * = (R),R1 = OH
b
c
64a : * = (S),R1 = OTs
64b : * = (R),R1 = OTs
65a : * = (S),R1 = N3
65b : * = (R),R1 = N3
O
R2
*
N
H
O
OR3
O
i
66a : * = (S),R2 = OMe, R3 = H
66b : * = (R), R2 = OMe, R3 = H
68a : * = (S),R2 = OMe, R3 = MOM
68b : * = (R),R2 = OMe, R3 = MOM
f
f
69a : * = (S),R2 = OH, R3 = MOM
69b : * = (R),R2 = OH, R3 = MOM
67a : * = (S),R2 = OH, R3 = H
67b : * = (R), R2 = OH, R3 = H
g, h
g, h
12 : * = (S), R2 = NHOH, R3 = H
13 : * = (R), R2 = NHOH, R3 = H
14 : * = (S),R2 = NHOH, R3 = MOM
15 : * = (R),R2 = NHOH, R3 = MOM
Scheme 9. Synthesis of 12–15. Reagents: (a) BH3–SMe2, NaBH4, THF; (b) TsCl, pyridine; (c) NaN3, DMF; (d) H2, Pd–C, 4 N HCl/MeOH, MeOH;
(e) 43, Et3N, CH2Cl2; (f) NaOH aq, THF–MeOH; (g) O-(2-methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (h) HCl, MeOH; (i) MOMCl,
iPr2NEt, CH2Cl2.
CO2H
CO2H
O
a
b
MeO2C
N
H
MeO2C
NH2
O
70
71
OR2
O
R1
O
N
H
O
72 : R1 = OMe, R2 = H
73 : R1 = OH, R2 = H
16 : R1 = NHOH, R2 = H
c
f
d, e
74 : R1 = OMe, R2 = MOM
75 : R1 = OH, R2 = MOM
17 : R1 = NHOH, R2 = MOM
c
d, e
Scheme 10. Synthesis of 16 and 17. Reagents : (a) 43, NaHCO3, THF–H2O; (b) BH3–ÆTHF, THF; (c) NaOH aq, MeOH; (d) O-(2-methoxypropane-
i
2-yl)hydroxylamine, EDC, HOBt, DMF; (e) HCl, MeOH; (f) MOMCl, Pr2NEt, CH2Cl2–THF.
3. Results and discussion
acid hydroxamate as a new chemical lead for an inhibi-
tor of MMP-2 and MMP-9, further chemical modifica-
tion to identify the optimum structure has been
continued.
The compounds listed in Tables 1–5 were tested to assess
their inhibitory potency against MMP-1 (human colla-
genase), MMP-2 (human gelatinase A), MMP-9 (human
gelatinase B), and MMP-3 (recombinant human strom-
elysin).9 Since the discovery of N-benzoyl 4-aminobutyric
As described in our previous paper,7 C2 substitution of
the 4-aminobutyric acid moiety tended to show an

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5409
O
CO2H
NH2
CO2H
b, c
a
MeO2C
MeO2C
N
*
*
H
I
70 : * = (S)
76 : * = (R)
77a : * = (S)
77b : * = (R)
OH
OR
2O
O
d
R1
N
H
MeO2C
N
H
*
*
O
I
O
78a : * = (S)
78b : * = (R)
79a : * = (S),R1 = OMe, R2 = H
79b : * = (R), R1 = OMe, R2 = H
e
80a : * = (S),R1 = OH, R2 = H
80b : * = (R),R1 = OH, R2 = H
h
f, g
18 : * = (S), R = NHOH, R2 = H
1
19 : * = (R),R1 = NHOH, R2 = H
81a : * = (S),R1 = OMe, R2 = MOM
81b : * = (R), R = OMe, R2 = MOM
1
e
82a : * = (S),R1 = OH, R2 = MOM
82b : * = (R),R1 = OH, R2 = MOM
f, g
20 : * = (S),R1 = NHOH, R2 = MOM
21 : * = (R),R1 = NHOH, R2 = MOM
Scheme 11. Synthesis of 18–21. Reagents: (a) 4-iodobenzoyl chloride, NaHCO3, Et2O–H2O; (b) HONSu, DCC, THF; (c) NaBH4, THF–H2O; (d) 3-
methoxy-1-propyne, Pd(PPh3)4, CuI, Et3N, DMF or 3-methoxy-1-propyne, PdCl2(PPh3)2, Et3N, DMF; (e) NaOH aq, THF–MeOH; (f) O-(2-
i
methoxypropane-2-yl)hydroxylamine, EDC, HOBt, DMF; (g) HCl, MeOH; (h) MOMCl, Pr2NEt, CH2Cl2.
increased inhibitory potency and chemical modification
A
R
O
H
N
of C1 carboxylic acid residue of the glutamic acid moiety
was useful to improve subtype selectivity and/or
inhibitory potency. We also reported on the optimization
process of the N-benzoyl moiety of 1 as described in Table
1.10 Replacement of the para-methyl residue of the N-ben-
zoyl moiety of 1 with a benzofuran-2-yl, phenoxy and
methoxymethyl-1-propyn-1-yl residues afforded 2–4,
respectively, with an increased inhibitory potency espe-
cially against MMP-2 and MMP-9 isoforms. On the basis
of the above-mentioned results, further chemical
modification of the 4-aminobutyric acid moiety of
N-(4-benzofuran-2-yl) benzoyl-4-aminobutyric acid
hydroxamate 2 was conducted as shown in Tables 2–4.
HO
N
H
O
Ar
B
C
O
O
H
N
HO
HO
N
H
O
O
R
Ar
Ar
R
H
N
N
H
Figure 1. Three scaffolds A–C derived from commercially available
starting materials.
For the efficient synthetic work, several commercially
available starting materials such as 4-aminobutyric acid,
(+)- and (ꢀ)-malic acid, and D- and L-glutamic acid were
selected. Using these starting materials, chemical modi-
fications producing three series of scaffolds A–C
(Fig. 1) could be developed.
inhibitor of MMP-2 and was a 4.5-fold less potent inhib-
itor of MMP-3. The 2S-benzyloxymethyloxy analog 7
was an equipotent and 2.2-fold more potent inhibitor
of MMP-2 and MMP-9 relative to 2, respectively, while
it retained the same activity and showed 2.4-fold more
potent activity for MMP-1 and MMP-3, respectively.
The 2R-benzyloxymethyloxy analog 8 showed a marked
reduction of inhibitory activity, especially for MMP-2,
because the introduction of a bulky substituent led to
undesirable conformation.
As shown in Table 2, synthesis and evaluation was car-
ried out for 2-hydroxy analogs of the 4-aminobutyric
acid, which was synthesized as an optically active
compound from the corresponding malic acid. The 2S-
hydroxy analog 5 showed similar inhibitory activity
for MMP-1, MMP-2, MMP-9, and MMP-3 to that of
2, while 2R-analog 6 was a nearly 2-fold less potent

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S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
Based on the results for 7, synthesis and evaluation of the
2-phenylalkyl analogs 9–11 was carried out as described
in Table 2. These compounds were synthesized and eval-
uated as a racemic mixture of 2R- and 2S-forms.
3-methoxymethyl-1-propyn-1-yl was selected as the p-
substituent because it was included in the relatively opti-
mum N-benzoyl residue 4 as a p-substituent. 4S-Hy-
droxymethyl analog 18 exhibited slightly more potent
inhibition of MMP-2, while the corresponding 4R-hy-
droxymethyl analog 19 had nearly the same IC50 value
as 4. 4S-Methoxymethyloxy analog 20 showed 5.3-fold
more potent inhibition of MMP-2 relative to 4, while
the corresponding 4R-isomer 21 showed 2.9-fold more
potent inhibitory activity for MMP-2. Thus, all of the
compounds listed in Table 5 showed less potent inhibition
of MMP-2 than 16 and 17 in Table 4. As a result, optimi-
zation of the C4-substituent seemed to have priority over
that of the p-substituent of the N-benzoyl residue.
Introduction of a benzyl moiety into the C2-position of
2 afforded 9, with 12-fold less potent inhibitory activity,
equipotent activity, and nearly 10-fold more potent
activity for MMP-2, MMP-9, and MMP-3, respectively.
Introduction of phenylethyl and phenylpropyl moieties
instead of a benzyl moiety at the C2-position of 2 gave
10 and 11, respectively, which also showed less potent
inhibition of MMP-2, while 11 retained its activity
against MMP-9. Interestingly, these three compounds
(9–11) all showed to be more potent inhibitors of
MMP-3 relative to 2. Thus, these C2-modifications
failed to significantly increase the inhibitory activity
for MMP-2 and MMP-9, while some of them showed
slightly increased inhibition of MMP-3, as illustrated
by compounds 7 and 9–10.
In summary, chemical modification of the 4-aminobu-
tyric acid moiety of 2 and 4 possessing the optimized
N-benzoyl moieties was conducted using commercially
available starting materials. Most of the compounds
tested were highly potent inhibitors of the gelatinases
(MMP-2 and MMP-9). Among the tested compounds,
16 and 17, which were derived from L-glutamic acid,
tended to show equipotent or slightly more potent inhib-
itory activities relative to 2 against all the isoforms. Fur-
ther optimization works including in vivo and PK
studies will be reported in due course. Compounds 9,
11, 16, and 17 were also expected to be a promising
chemical lead to identify a new MMP-3 inhibitor.
Chemical modification of C3 on compound 2 was also
carried out, as shown in Table 3. Again, the synthesis
and evaluation of 3-hydroxy analogs derived from malic
acid was conducted due to the ease of synthesis. Intro-
duction of a 3S-hydroxy moiety into 2 afforded 12,
which showed slightly weaker inhibitory activities for
MMP-2 and MMP-9. The corresponding 3R-hydroxy
isomer 13 demonstrated nearly 10-fold less potent inhib-
itory activity for MMP-2 relative to that of 2, while it
showed 5.5-fold weaker inhibitory activity against
MMP-3. Thus, the 3S-hydroxy analog 12 showed 5.2-
fold more potent inhibitory activity for MMP-2 than
the corresponding 3R-hydroxy analog. The correspond-
ing derivatives 14 and 15 were also evaluated. Both the
3S-methoxymethyloxy analog 14 and the corresponding
3R-isomer 15 showed 8.6-fold less potent inhibitory
activity for MMP-2 regardless of their stereochemistry.
Thus, the pocket for the C3-substituent seemed to be
smaller than that accepting the C2-substituent.
4. Experimental
Analytical samples were homogeneous as confirmed by
thin-layer chromatography (TLC) and yielded spectro-
scopic data consistent with the assigned structures. All
1H NMR spectra were obtained with a Varian Gemi-
ni-200 or MERCURY-300 spectrometer. The chemical
shift values are reported in parts per million (d) and cou-
pling constants (J) in hertz (Hz). Fast atom bombard-
ment (FAB) and electron ionization (EI) mass spectra
were obtained with a JEOL JMS-DX303HF or JMS-
700 spectrometer. Atmospheric pressure chemical ioni-
zation (APCI) mass spectra were determined by a Hit-
achi M-1200H spectrometer. Matrix-assisted laser
desorption ionization (MALDI) mass spectra were ob-
tained on a PerSeptive Biosystems VoyagerTM Elite spec-
trometer. IR spectra were measured using a Perkin-
Elmer FTIR 1760X or JASCO FTIR-430 spectrometer.
Column chromatography was carried out using silica gel
[Merck silica gel 60 (0.063–0.200 mm), Wako Gel C200,
Fuji Silysia FL60D, or Fuji Silysia BW-235]. TLC was
also performed on silica gel (Merck TLC plate, silica
gel 60 F254). The following abbreviations for solvents
and reagents are used: THF, tetrahydrofuran; EtOAc,
ethylacetate; MeOH, methanol; DMF, N,N-dimethyl-
formamide; CH2Cl2, dichloromethane; CHCl3, chloro-
As shown in Table 4, chemical modification of the C4
position of compound 2 was carried out with the 4S-iso-
mer, because it was predicted to be more potent than the
corresponding 4R-isomer. Synthesis and evaluation of
4S-hydroxymethyl analogs, which could be derived from
L-glutamic acid, was also carried out due to the ease of
synthesis. Introduction of a 4S-hydroxymethyl residue
into 2 afforded 16, which showed an equipotent, 4.5-fold
more potent, and 3.3-fold more potent inhibition of
MMP-2, MMP-9, and MMP-3, respectively. Introduc-
tion of the 4S-methoxymethyloxy residue into 2 resulted
in 17, which showed nearly 4.0-, 7.0-, and 7.8-folds more
potent inhibitory activity for MMP-2, MMP-9, and
MMP-3, respectively. As a result, chemical modification
of C4 seemed to be most promising for further optimiza-
tion of this series of analogs based on both the SAR
data and the relative ease of synthesis.
form;
EDCÆHCl,
1-[3-(dimethylamino)propyl]-3-
ethylcarbodiimide hydrochloride; HOBt, 1-hydrox-
ybenzotriazole; Et2O, diethyl ether; LiHMDS, lithium
hexamethyldisilazide; LDA, lithium diisopropylamide;
FITC, fluorescein isothiocyanate; MOCAc, 7-methoxy-
coumarin-4-acetyl; Dpa, N-3-(2,4-dinitrophenyl)-L-2,3-
diaminopropionyl; Dnp, 2,4-dinitrophenyl.
As shown in Table 5, further chemical modification of
the para-substituent of the N-benzoyl residue was
continued using the most optimum partial structure,
that is, the C4-substituted 4-aminobutyric acid. The

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5411
4.1. 4-[(4-Methylbenzoyl)amino]butanoic acid (23)
benzofuran-2-boronic acid (2.64 g, 18.1 mmol), dichlor-
obis(triphenylphosphine)palladium(II) (635 mg, 0.905
mmol), and triethylamine (5 mL). After being stirred
at 80 °C for 6 h, the reaction mixture was poured into
1 N HCl and extracted with EtOAc. The organic layer
was washed with brine and dried over Na2SO4. Removal
of the volatiles in vacuo provided a solid, which was
washed with Et2O–n-hexane to give 3.60 g (75%) of 26
as a light brown powder: TLC Rf = 0.61 (EtOAc–n-hex-
ane, 1:9); 1H NMR (300 MHz, CDCl3) d 8.12 (d,
J = 8.4 Hz, 2H), 7.93 (d, J = 8.4 Hz, 2H), 7.65–7.58
(m, 1H), 7.58–7.51 (m, 1H), 7.37–7.21 (m, 2H), 7.16 (s,
1H), 4.41 (q, J = 7.2 Hz, 2H), 1.42 (t, J = 7.2 Hz, 3H).
To a stirred suspension of 4-aminobutyric acid (1.13 g,
11.0 mmol) in THF (21 mL) were added 1 N NaOH
(21.0 mL, 21.0 mmol) at 0 °C and then 22 (1.55 g,
10.0 mmol). After being stirred at room temperature
for 3 h, the reaction mixture was acidified with 2 N
HCl and extracted with EtOAc. The organic layer was
washed with brine and dried over MgSO4. Removal of
the volatiles in vacuo provided a solid, which was
washed with Et2O to give 2.00 g (90%) of 23 as a white
crystal: TLC Rf = 0.58 (CHCl3–MeOH–AcOH, 18:2:1);
1H NMR (200 MHz, CDCl3) d 7.73 (d, J = 8.4 Hz,
2H), 7.40 (m, 1H), 7.21 (d, J = 8.4 Hz, 2H), 3.47 (m,
2H), 2.41 (t, J = 7.3 Hz, 2H), 2.38 (s, 3H), 1.94 (m, 2H).
4.5. 4-(1-Benzofuran-2-yl)benzoic acid (27)
4.2. N-[4-(Benzyloxy)amino-4-oxobutyl]-4-methyl-
benzamide (24)
To a stirred solution of 26 (3.40 g, 12.8 mmol) in diox-
ane (15 mL) was added 1 N NaOH (15.3 mL,
15.3 mmol). After being stirred at room temperature
for 9 h, the reaction mixture was poured into 1 N HCl
and extracted with EtOAc–THF. The organic layer
was washed with brine and dried over MgSO4. Removal
of the volatiles in vacuo provided a crude solid, which
was washed with EtOAc–Et2O to give 2.10 g (69%) of
27 as a pale gray powder: TLC Rf = 0.43 (CHCl3–
MeOH–AcOH, 100:10:1); 1H NMR (200 MHz,
DMSO-d6) d 8.04 (m, 4H), 7.72–7.63 (m, 2H), 7.60 (br
s, 1H), 7.41–7.24 (m, 2H).
To a stirred solution of 23 (885 mg, 4.00 mmol) in DMF
(5 mL) were added O-benzylhydroxylamine hydrochlo-
ride (1.28 g, 8.00 mmol), N,N-diisopropylethylamine
(3.48 mL, 20.0 mmol), HOBtÆH2O (1.35 g, 8.80 mmol),
and EDCÆHCl (1.69 g, 8.80 mmol). The reaction mixture
was stirred at room temperature for 50 h, then diluted
with EtOAc and washed sequentially with 1 N HCl, sat-
urated NaHCO3, and brine. The organic layer was dried
over MgSO4. Removal of the volatiles in vacuo provided
a solid, which was washed with Et2O to give 986 mg
(76%) of 24 as a white powder: TLC Rf = 0.52
4.6. Ethyl 4-{[4-(1-benzofuran-2-yl)benzoyl]amino}but-
anoate (28)
1
(CHCl3–MeOH, 10:1); H NMR (200 MHz, CDCl3) d
9.24 (s, 1H), 7.68 (d, J = 8.2 Hz, 2H), 7.37 (m, 5H),
7.23 (d, J = 8.2 Hz, 2H), 6.66 (m, 1H), 4.90 (s, 2H),
3.46 (dt, J = 6.0, 5.8 Hz, 2H), 2.39 (s, 3H), 2.17 (m,
2H), 1.92 (m, 2H).
To a stirred solution of 27 (500 mg, 3.00 mmol) in DMF
(15 mL) were added 4-aminobutyric acid ethyl ester
hydrochloride
(715 mg,
3.00 mmol),
HOBtÆH2O
(551 mg, 3.60 mmol), triethylamine (920 lL, 6.60 mmol),
and EDCÆHCl (690 mg, 3.60 mmol). After being stirred
at room temperature for 2 days, the reaction mixture
was poured into 1 N HCl and extracted with EtOAc–
THF. The organic layer was washed with saturated
NaHCO3, brine and dried over Na2SO4. Removal of
the volatiles in vacuo provided a solid, which was
washed with EtOAc–Et2O to give 732 mg (70%) of 28
as a white powder: TLC Rf = 0.38 (EtOAc–n-hexane,
1:1); 1H NMR (200 MHz, DMSO-d6) d 8.57 (t,
J = 5.4 Hz, 1H), 8.01 (d, J = 9.2 Hz, 2H), 7.96 (d,
J = 9.2 Hz, 2H), 7.71–7.62 (m, 2H), 7.57 (br s, 1H),
7.39–7.23 (m, 2H), 4.04 (q, J = 7.0 Hz, 2H), 3.37–3.25
(m, 2H), 2.36 (t, J = 7.4 Hz, 2H), 1.86–1.72 (m 2H).
4.3. N-[4-(Hydroxyamino)-4-oxobutyl]-4-methylbenza-
mide (1)
Catalytic hydrogenation of 24 (504 mg, 1.54 mmol) in
MeOH (4 mL) was conducted at room temperature for
2 h in the presence of 10% palladium on carbon
(50 mg) at atmospheric pressure. Removal of the cata-
lyst by filtration, followed by evaporation, afforded a
gray solid, which was purified by silica gel chromatogra-
phy with MeOH–CHCl3, 1:10, as an eluent. Evapora-
tion of the product-rich fractions provided a solid,
which was recrystallized from Et2O to provide 311 mg
(85%) of 1 as a white crystal: TLC Rf = 0.23 (CHCl3–
MeOH, 10:1); MS (APCI, neg. 40 V) m/z 235 (M–H)ꢀ;
IR (KBr) 1674, 1613, 1608, 1564, 1510, 1458, 1436,
1360, 1332, 1313, 1258, 1233, 1197, 1178, 1101, 1024,
4.7. 4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}butanoic
acid (29)
969 cmꢀ1 1H NMR (200 MHz, DMSO-d6) d 10.39
;
(1H, s), 8.70 (s, 1H), 8.40 (t, J = 5.2 Hz, 1H), 7.74 (d,
J = 8.1 Hz, 2H), 7.25 (d, J = 8.1 Hz, 2H), 3.24 (dt,
J = 6.6, 5.2 Hz, 2H), 2.35 (s, 3H), 2.02 (t, J = 7.7 Hz,
2H), 1.74 (m, 2H); HRMS (FAB) calcd for
C12H17N2O3: 237.1239. Found: 237.1244.
To a stirred solution of 28 (670 mg, 1.91 mmol) in THF
(5 mL) was added 1 N NaOH (4.40 mL, 4.40 mmol).
After being stirred at room temperature for 3 h, the
reaction mixture was poured into 1 N HCl and extracted
with EtOAc–THF. The organic layer was washed with
brine and dried over Na2SO4. Removal of the volatiles
in vacuo provided 617 mg (100%) of 29 as a white
powder, which was used for the next reaction without
further purification: TLC Rf = 0.40 (CHCl3–MeOH–
AcOH, 100:10:1); 1H NMR (200 MHz, DMSO-d6) d
4.4. Ethyl 4-(1-benzofuran-2-yl)benzoate (26)
To a stirred solution of ethyl 4-iodobenzoate (25)
(5.00 g, 18.1 mmol) in DMF (10 mL) were added

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S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
8.58 (t, J = 5.6 Hz, 1H), 8.01 (d, J = 9.2 Hz, 2H), 7.96 (d,
J = 9.2 Hz, 2H), 7.71–7.63 (m, 2H), 7.57 (d, J = 0.8 Hz,
1H), 7.39–7.23 (m, 2H), 3.32–3.25 (m, 2H), 2.29 (t,
J = 7.6 Hz, 2H), 1.84–1.70 (m, 2H).
J = 8.8, 2.8 Hz, 2H), 7.37–7.46 (m, 2H), 7.19 (tt,
J = 7.2, 1.2 Hz, 1H), 6.97–7.09 (m, 4H), 3.22 (dt,
J = 6.6, 5.6 Hz, 2H), 1.99 (t, J = 7.6 Hz, 2H), 1.71 (tt,
J = 7.6, 6.6 Hz, 2H); HRMS (FAB) calcd for
C17H19N2O4: 315.1345. Found: 315.1342.
4.8. 4-(1-Benzofuran-2-yl)-N-[4-(hydroxyamino)-4-
oxobutyl]benzamide (2)
4.11. Methyl 4-(3-methoxy-1-propynyl)benzoate (34)
To a stirred solution of 29 (550 mg, 1.70 mmol) in DMF
(10 mL) at 0 °C were added O-(2-methoxypropane-2-
yl)hydroxylamine (455 mg, 5.10 mmol), HOBtÆH2O
(391 mg, 2.55 mmol), and EDCÆHCl (489 mg,
2.55 mmol). After being stirred at room temperature
for 3 h, the reaction mixture was poured into water
and extracted with EtOAc. The organic layer was
washed with saturated NaHCO3, brine, and dried over
Na2SO4. Removal of the volatiles in vacuo provided
an oily residue, which was dissolved in MeOH (10 mL)
and the resulting solution was acidified up to pH 3 with
1 N HCl. After being stirred at room temperature for
10 min, the reaction mixture was poured into water
and extracted with EtOAc. The organic layer was
washed with brine and dried over Na2SO4. Removal
of the volatiles in vacuo provided a crude solid, which
was washed with Et2O to give 218 mg (38%) of 2 as a
white powder: TLC Rf = 0.22 (CHCl3–MeOH–AcOH,
100:10:1); MS (FAB, pos.) m/z 339 (M+H)+; IR (KBr)
The title compound was obtained quantitatively from
methyl 4-iodobenzoate (33) and 3-methoxy-1-propyne
according to the same procedures as described for the
preparation of 26. Purification was performed by
silica gel chromatography with EtOAc–n-hexane, 1:9, as
an eluent: TLC Rf = 0.51 (EtOAc–n-hexane, 1:4); 1H
NMR (300 MHz, CDCl3) d 7.97 (d, J = 8.7 Hz, 2H),
7.49 (d, J = 8.7 Hz, 2H), 4.34 (s, 2H), 3.91 (s, 3H), 3.46
(s, 3H).
4.12. 4-(3-Methoxy-1-propynyl)benzoic acid (35) and
ethyl 4-{[4-(3-methoxy-1-propynyl)benzoyl]amino}but-
anoate (36)
The carboxylic acid 35 was obtained in 79% yield from
34 according to the same procedures as described for
the preparation of 27. The ester 36 was obtained as a
white powder in 79% yield from 35 according to the
same procedures as described for the preparation of
28. Purification was performed by silica gel chromatog-
raphy with CHCl3–EtOAc–AcOH, 90:10:3, as an eluent:
MS (MALDI, pos.) m/z 342 (M+K)+, 326 (M+Na)+,
1633, 1541, 1451, 1306, 1030 cmꢀ1
;
1H NMR
(200 MHz, DMSO-d6): d 10.39 (br s, 1H), 8.59 (t,
J = 5.8 Hz, 1H), 8.01 (d, J = 9.0 Hz, 2H), 7.96 (d,
J = 9.0 Hz, 2H), 7.67 (m, 2H), 7.57 (d, J = 0.5 Hz,
1H), 7.39–7.23 (m, 2H), 3.27 (q, J = 5.8 Hz, 2H), 2.03
(t, J = 7.6 Hz, 2H), 1.76 (m, 2H); HRMS (FAB) calcd
for C19H19N2O4: 339.1345. Found: 339.1349.
1
304 (M+H)+; H NMR (200 MHz, CDCl3) d 7.74 (d,
J = 8.6 Hz, 2H), 7.51 (d, J = 8.6 Hz, 2H), 6.65 (m,
1H), 4.34 (s, 2H), 4.13 (q, J = 7.2 Hz, 2H), 3.51 (q,
J = 6.8 Hz, 2H), 3.46 (s, 3H), 2.45 (t, J = 6.8 Hz, 2H),
1.97 (quintet, J = 6.8 Hz, 2H), 1.24 (t, J = 7.2 Hz, 3H).
4.9. Ethyl 4-[(4-phenoxybenzoyl)amino]butanoate (31)
and 4-[(4-phenoxybenzoyl)amino]butanoic acid (32)
4.13. 4-{[4-(3-Methoxy-1-propynyl)benzoyl]amino}buta-
noic acid (37)
The ester 31 was obtained as a white powder in 75%
yield from 30 according to the same procedures as de-
scribed for the preparation of 28. Compound 31: TLC
Rf = 0.76 (CHCl3–MeOH–H2O–AcOH, 100:10:1:1).
The carboxylic acid 32 was obtained as a white powder
in 98% yield from 31 according to the same procedures
as described for the preparation of 29. Compound 32:
TLC Rf = 0.47 (CHCl3–MeOH–H2O–AcOH, 100:10:1:1);
1H NMR (200 MHz, DMSO-d6) d 8.41(t, J = 5.4 Hz,
1H), 7.85 (d, J = 8.4 Hz, 2H), 7.42 (t, J = 8.0 Hz, 2H),
7.18 (t, J = 7.2 Hz, 1H), 6.97–7.08 (m, 4H), 3.24 (q,
J = 6.6 Hz, 2H), 2.25 (t, J = 7.4 Hz, 2H), 1.72 (tt,
J = 7.4, 6.6 Hz, 2H).
The title compound was obtained as a white powder in
99% yield from 36 according to the same procedures
as described for the preparation of 29: MS (MALDI,
pos.) m/z 314 (M+K)+, 298 (M+Na)+, 276 (M+H)+;
1H NMR (200 MHz, DMSO-d6) d12.03 (br s, 1H),
8.54 (t, J = 5.3 Hz, 1H), 7.85 (d, J = 8.2 Hz, 2H), 7.52
(d, J = 8.2 Hz, 2H), 4.34 (s, 2H), 3.35 (s, 3H), 3.34–
3.22 (m, 2H), 2.28 (t, J = 7.0 Hz, 2H), 1.76 (quintet,
J = 7.0 Hz, 2H).
4.14. N-[4-(Hydroxyamino)-4-oxobutyl]-4-(3-methoxy-1-
propynyl)benzamide (4)
4.10. N-[4-(Hydroxyamino)-4-oxobutyl]-4-phenoxy-
benzamide (3)
The title compound was obtained as a white powder in
71% yield from 37 according to the same procedures as de-
scribed for the preparation of 2: TLC Rf = 0.32 (CHCl3–
MeOH–AcOH, 18:2:1); MS (MALDI, pos.) m/z 313
(M+Na)+, 291 (M+H)+; IR (KBr) 1633, 1536, 1453,
1365, 1303, 1095 cmꢀ1; 1H NMR (200 MHz, DMSO-d6)
d 10.39 (s, 1H), 8.57 (t, J = 5.5 Hz, 1H), 7.85 (d, J =
8.6 Hz, 2H), 7.53 (d, J = 8.6 Hz, 2H), 4.35 (s, 2H), 3.35
(s, 3H), 3.25 (dt, J = 7.2, 5.5 Hz, 2H), 2.02 (t, J =
7.2 Hz, 2H), 1.74 (quintet, J = 7.2 Hz, 2H); HRMS
(FAB) calcd for C15H19N2O4: 291.1345. Found: 291.1347.
The title compound was obtained as a white powder in
59% yield from 32 according to the same procedures
as described for the preparation of 2: TLC Rf = 0.25
(CHCl3–MeOH–H2O–AcOH, 100:10:1:1); MS (MAL-
DI, pos.) m/z 315 (M+H)+; IR (KBr) 1633, 1544,
1489, 1370, 1303, 1258, 1165, 1100, 1028, 972 cmꢀ1
;
1H NMR (200 MHz, DMSO-d6) d 10.36 (br s, 1H),
8.69 (br s, 1H), 8.41 (t, J = 5.6 Hz, 1H), 7.85 (dt,

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5413
4.15. (5S)-5-(2-Hydroxyethyl)-2,2-dimethyl-1,3-dioxolan-
4-one (39a)
washed with brine and dried over Na2SO4. Removal of
the volatiles in vacuo provided an oily residue, which
was purified by silica gel chromatography with
EtOAc–n-hexane, 1:6, as an eluent. Evaporation of the
product-rich fractions provided 11.5 g (85%) of 41a as
To a stirred solution of 38a (29.4 g, 169 mmol) in THF
(300 mL) was added dropwise a solution of borane–tet-
rahydrofuran complex (203 mL of a 1.0 M solution in
THF, 203 mmol) at 0 °C. After being stirred at room
temperature for 4 h, the reaction mixture was quenched
with saturated NH4Cl and extracted with EtOAc. The
organic layer was washed with brine and dried over
Na2SO4. Removal of the volatiles in vacuo provided
20.2 g (75%) of 39a as a yellow oil: TLC Rf = 0.44
1
a yellow oil: TLC Rf = 0.68 (EtOAc–n-hexane, 1:3); H
NMR (200 MHz, CDCl3) d 4.49 (dd, J = 7.2, 4.8 Hz,
1H), 3.54–3.47 (m, 2H), 2.25–1.90 (m, 2H), 1.63 (s,
3H), 1.56 (s, 3H).
4.20. (5R)-5-(2-Azidoethyl)-2,2-dimethyl-1,3-dioxolan-4-
one (41b)
1
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, CDCl3) d
4.58 (dd, J = 6.8, 5.2 Hz, 1H), 3.95–3.77 (m, 2H),
2.28–1.93 (m, 2H), 1.64 (s, 3H), 1.57 (s, 3H).
The title compound was obtained as a yellow oil in 75%
yield from 40b according to the same procedures as de-
scribed for the preparation of 41a: TLC Rf = 0.68
1
4.16. (5R)-5-(2-Hydroxyethyl)-2,2-dimethyl-1,3-dioxo-
lan-4-one (39b)
(EtOAc–n-hexane, 1:3); H NMR (200 MHz, CDCl3) d
4.49 (dd, J = 7.2, 4.8 Hz, 1H), 3.54–3.47 (m, 2H),
2.25–1.90 (m, 2H), 1.63 (s, 3H), 1.56 (s, 3H).
The title compound was obtained as a yellow oil in 89%
yield from 38b according to the same procedures as de-
scribed for the preparation of 39a: TLC Rf = 0.44
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, CDCl3) d
4.58 (dd, J = 6.8, 5.2 Hz, 1H), 3.95–3.77 (m, 2H),
2.28–1.93 (m, 2H), 1.64 (s, 3H), 1.57 (s, 3H).
4.21. Methyl (2S)-4-azido-2-hydroxybutanoate (42a)
1
A solution of 41a (1.50 g, 8.10 mmol) and p-toluenesulf-
onic acid monohydrate (69.7 mg, 0.405 mmol) in MeOH
(100 mL) was refluxed for 1.5 h. The reaction mixture
was evaporated. The residue was diluted with EtOAc
and washed with saturated NaHCO3 and brine. The
organic layer was dried over Na2SO4. Removal of the
volatiles in vacuo provided 945 mg (74%) of 42a as a yel-
low oil: TLC Rf = 0.50 (EtOAc–n-hexane, 1:3); 1H
NMR (200 MHz, DMSO-d6) d 5.60 (d, J = 6.0 Hz,
1H), 4.16–4.07 (m, 1H), 3.64 (s, 3H), 3.41 (t,
J = 6.6 Hz, 2H), 1.98–1.68 (m, 2H).
4.17. 2-[(4S)-2,2-Dimethyl-5-oxo-1,3-dioxolan-4-yl]ethyl
4-methylbenzenesulfonate (40a)
To a stirred solution of 39a (19.8 g, 124 mmol) in pyri-
dine (160 mL) at 0 °C was added p-toluenesulfonyl chlo-
ride (25.9 g, 136 mmol). After being stirred at room
temperature overnight, the reaction mixture was diluted
with water and extracted with EtOAc. The organic layer
was washed with brine and dried over Na2SO4. Removal
of the volatiles in vacuo provided an oily residue, which
was purified by silica gel chromatography with EtOAc–
n-hexane, 1:3, as an eluent. Evaporation of the product-
rich fractions provided 24.2 g (61%) of 40a as a brown
oil: TLC Rf = 0.33 (EtOAc–n-hexane, 1:3); 1H NMR
(200 MHz, CDCl3) d 7.81 (d, J = 8.4 Hz, 2H), 7.36 (d,
J = 8.4 Hz, 2H), 4.45–4.40 (m, 1H), 4.31–4.10 (m, 2H),
2.46 (s, 3H), 2.35–2.18 (m 1H), 2.10–1.92 (m, 1H),
1.57 (s, 3H), 1.51 (s, 3H).
4.22. Methyl (2R)-4-azido-2-hydroxybutanoate (42b)
The title compound was obtained as a yellow oil in 83%
yield from 41b according to the same procedures as de-
scribed for the preparation of 42a: TLC Rf = 0.50
1
(EtOAc–n-hexane, 1:3); H NMR (200 MHz, DMSO-
d6) d 5.60 (d, J = 6.0 Hz, 1H), 4.16–4.07 (m, 1H), 3.64
(s, 3H), 3.41 (t, J = 6.6 Hz, 2H), 1.98–1.68 (m, 2H).
4.23. 4-(1-Benzofuran-2-yl)benzoyl chloride (43)
4.18. 2-[(4R)-2,2-Dimethyl-5-oxo-1,3-dioxolan-4-yl]ethyl
4-methylbenzenesulfonate (40b)
A suspension of 27 (13.4 g, 56.3 mmol) in SOCl2
(80 mL) was refluxed for 3 h, and the reaction mixture
was evaporated. The resulting oily residue was diluted
with toluene and the volatiles were removed in vacuo.
The resulting solid was washed with Et2O–n–hexane to
The title compound was obtained as a light brown oil in
29% yield from 39b according to the same procedures as
described for the preparation of 40a: TLC Rf = 0.33
1
give 12.7 g (88%) of 43 as a yellow powder: H NMR
1
(EtOAc–n-hexane, 1:3); H NMR (200 MHz, CDCl3) d
(200 MHz, CDCl3) d 8.19 (d, J = 8.8 Hz, 2H), 7.98 (d,
J = 8.8 Hz, 2H), 7.68–7.61 (m, 1H), 7.59–7.53 (m, 1H),
7.42–7.23 (m, 3H).
7.81 (d, J = 8.4 Hz, 2H), 7.36 (d, J = 8.4 Hz, 2H), 4.45–
4.40 (m, 1H), 4.31–4.10 (m, 2H), 2.46 (s, 3H), 2.35–2.18
(m 1H), 2.10–1.92 (m, 1H), 1.57 (s, 3H), 1.51 (s, 3H).
4.24. Methyl (2S)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-2-hydroxybutanoate (44a)
4.19. (5S)-5-(2-Azidoethyl)-2,2-dimethyl-1,3-dioxolan-4-
one (41a)
Catalytic hydrogenation of 42a (900 mg, 5.73 mmol) in
MeOH–4 N HCl/MeOH (90 mL–2.86 mL) was conduct-
ed for 2 h at room temperature in the presence of 10%
palladium on carbon (90 mg) at an atmospheric
pressure. The catalyst was removed by filtration and
A solution of 40a (23.1 g, 73.6 mmol) and sodium azide
(5.26 g, 80.9 mmol) in DMF (160 mL) was stirred at
80 °C for 20 min. The reaction mixture was poured into
water and extracted with EtOAc. The organic layer was

5414
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
the volatiles were removed in vacuo. The resulting resi-
due was used for the next reaction without further puri-
fication. To a stirred solution of the residue in CH2Cl2
(20 mL) were added triethylamine (2.4 mL, 17.2 mmol)
at 0 °C and then 4-(1-benzofuran-2-yl)benzoyl chloride
(43) (1.47 g, 5.73 mmol). After being stirred at room
temperature for 2 h, the reaction mixture was poured
into 1 N HCl and extracted with EtOAc. The organic
layer was washed with water, brine and dried over
Na2SO4. Removal of the volatiles in vacuo provided a
solid, which was washed with EtOAc–n-hexane to give
1.61 g (80%) of 44a as a beige powder: TLC Rf = 0.20
(CHCl3–MeOH–H2O, 100:20:1); MS (MALDI, pos.)
m/z 377 (M+Na)+, 355 (M+H)+; IR (KBr) 1635, 1539,
1497, 1450, 1306, 1107, 1062 cmꢀ1
;
1H NMR
(200 MHz, DMSO-d6) d 10.49 (br s, 1H), 8.55 (t,
J = 5.4 Hz, 1H), 8.01 (d, J = 9.0 Hz, 2H), 7.96 (d,
J = 9.0 Hz, 2H), 7.71–7.62 (m, 2H), 7.57 (br s, 1H),
7.39–7.23 (m, 2H), 5.00–3.60 (br, 1H), 3.94 (dd,
J = 8.2, 4.2 Hz, 1H), 3.41–3.31 (m, 2H), 2.02–1.64 (m,
30
D
2H); optical rotation ½aꢁ ꢀ11.5 (c 0.38, DMF); HRMS
(FAB) calcd for C19H19N2O5: 355.1294. Found:
355.1294.
1
(EtOAc–n-hexane, 2:1); H NMR (200 MHz, DMSO-
4.29. 4-(1-Benzofuran-2-yl)-N-[(3R)-3-hydroxy-4-
(hydroxyamino)-4-oxobutyl]benzamide (6)
d6) d 8.58 (t, J = 6.0 Hz, 1H), 8.01 (d, J = 8.8 Hz, 2H),
7.96 (d, J = 8.8 Hz, 2H), 7.71–7.63 (m, 2H), 7.57 (br s,
1H), 7.39–7.24 (m, 2H), 4.19–4.10 (m, 1H), 3.62 (s,
3H), 3.38 (q, J = 6.0 Hz, 2H), 2.06–1.68 (m, 2H).
The title compound was obtained as a white powder in
84% yield from 45b according to the same procedures
as described for the preparation of 2: TLC Rf = 0.42
(CHCl3–MeOH–H2O, 100:20:1); MS (MALDI, pos.)
m/z 355 (M+H)+; IR (KBr) 1634, 1539, 1497, 1450,
4.25. Methyl (2R)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-2-hydroxybutanoate (44b)
1
1306, 1108, 1062 cmꢀ1; H NMR (200 MHz, DMSO-
The title compound was obtained as a beige powder in
63% yield from 42b according to the same procedures
as described for the preparation of 44a: TLC
d6) d 10.49 (br s, 1H), 8.55 (t, J = 5.6 Hz, 1H), 8.01 (d,
J = 9.0 Hz, 2H), 7.96 (d, J = 9.0 Hz, 2H), 7.71–7.63
(m, 2H), 7.57 (br s, 1H), 7.39–7.23 (m, 2H), 6.00–4.20
1
Rf = 0.20 (EtOAc–n-hexane, 2:1); H NMR (200 MHz,
8.58 (t, J = 6.0 Hz, 1H), 8.01 (d,
(br, 1H), 3.94 (dd, J = 8.2, 4.2 Hz, 1H), 3.41–3.31 (m,
30
D
DMSO-d6):
d
2H), 2.02–1.62 (m, 2H); optical rotation ½aꢁ +10.4 (c
J = 8.8 Hz, 2H), 7.96 (d, J = 8.8 Hz, 2H), 7.71–7.63
(m, 2H), 7.57 (br s, 1H), 7.39–7.24 (m, 2H), 4.19–4.10
(m, 1H), 3.62 (s, 3H), 3.38 (q, J = 6.0 Hz, 2H), 2.06–
1.68 (m, 2H).
0.44, DMF); HRMS (FAB) calcd for C19H19N2O5:
355.1294. Found: 355.1295.
4.30. Methyl (2S)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-2-[(benzyloxy)methoxy]butanoate (46a)
4.26. (2S)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-2-
hydroxybutanoic acid (45a)
To a stirred solution of 44a (200 mg, 0.566 mmol) in
CH2Cl2 (1 mL) were added N,N-diisopropylethylamine
(2 mL) at 0 °C and then benzyloxymethylchloride
(784 lL, 5.66 mmol). After being stirred at 50 °C for
30 min, the reaction mixture was poured into 1 N HCl
and extracted with EtOAc. The organic layer was
washed with water, brine and dried over Na2SO4.
Removal of the volatiles in vacuo provided an oily res-
idue, which was purified by silica gel chromatography
with EtOAc–n-hexane, 2:3, as an eluent. Evaporation
of the product-rich fractions provided 176 mg (66%) of
46a as a white powder: TLC Rf = 0.47 (EtOAc–n-hex-
ane, 1:1); 1H NMR (200 MHz, CDCl3) d 7.89 (d,
J = 8.8 Hz, 2H), 7.79 (d, J = 8.8 Hz, 2H), 7.64–7.52
(m, 2H), 7.37–7.21 (m, 9H), 7.12 (br s, 1H), 4.92 (d,
J = 7.0 Hz, 1H), 4.87 (d, J = 7.0 Hz, 1H), 4.68 (s, 2H),
The title compound was obtained as an off-white pow-
der in 77% yield from 44a according to the same proce-
dures as described for the preparation of 29: TLC
1
Rf = 0.10 (CHCl3–MeOH–AcOH, 100:10:1); H NMR
(200 MHz, DMSO-d6) d 8.49 (t, J = 5.6 Hz, 1H), 7.92
(d, J = 8.8 Hz, 2H), 7.87 (d, J = 8.4 Hz, 2H), 7.62–7.53
(m, 2H), 7.48 (d, J = 0.6 Hz, 1H), 7.30–7.14 (m, 2H),
3.95 (dd, J = 8.4, 4.4 Hz, 1H), 3.29 (q, J = 6.6 Hz, 2H),
1.98–1.58 (m, 2H).
4.27. (2R)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-2-
hydroxybutanoic acid (45b)
The title compound was obtained as a white powder in
93% from 44b yield according to the same procedures
as described for the preparation of 29: TLC Rf = 0.10
4.38 (dd, J = 6.0, 5.0 Hz, 1H), 2.20–2.10 (m, 2H); optical
30
D
rotation ½aꢁ ꢀ42.4 (c 0.40, CHCl3).
(CHCl3–MeOH–AcOH,
100:10:1);
1H
NMR
(200 MHz, DMSO-d6) d 8.49 (t, J = 5.6 Hz, 1H), 7.92
(d, J = 8.8 Hz, 2H), 7.87 (d, J = 8.4 Hz, 2H), 7.62–7.53
(m, 2H), 7.48 (d, J = 0.6 Hz, 1H), 7.30–7.14 (m, 2H),
3.95 (dd, J = 8.4, 4.4 Hz, 1H), 3.29 (q, J = 6.6 Hz, 2H),
1.98–1.58 (m, 2H).
4.31. Methyl (2R)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-2-[(benzyloxy)methoxy]butanoate (46b)
The title compound was obtained as a white powder in
82% yield from 44b according to the same procedures
as described for the preparation of 46a: TLC Rf = 0.47
1
4.28. 4-(1-Benzofuran-2-yl)-N-[(3S)-3-hydroxy-4-
(hydroxyamino)-4-oxobutyl]benzamide (5)
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, CDCl3) d
7.89 (d, J = 8.8 Hz, 2H), 7.79 (d, J = 8.8 Hz, 2H),
7.64–7.52 (m, 2H), 7.37–7.21 (m, 9H), 7.12 (br s, 1H),
4.92 (d, J = 7.0 Hz, 1H), 4.87 (d, J = 7.0 Hz, 1H), 4.68
(s, 2H), 4.38 (dd, J = 6.0, 5.0 Hz, 1H), 2.20–2.10 (m,
2H).
The title compound was obtained as a white powder in
86% yield from 45a according to the same procedures
as described for the preparation of 2: TLC Rf = 0.42

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5415
4.32. (2S)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-2-
[(benzyloxy)methoxy]butanoic acid (47a)
4.36. Ethyl 4-[(4-iodobenzoyl)amino]butanoate (49) and
ethyl 2-benzyl-4-[(4-iodobenzoyl)amino]butanoate (50)
The title compound was obtained as a white powder in
96% yield from 46a according to the same procedures
as described for the preparation of 29: TLC Rf = 0.45
The ester 49 was obtained as a white powder in 75%
yield from 48 according to the same procedures as de-
scribed for the preparation of 28. To a stirred solution
of 49 (410 mg, 1.14 mmol) in THF (10 mL) was added
dropwise LiHMDS (2.51 mL of a 1.0 M solution in
THF) at ꢀ78 °C. The reaction mixture was stirred for
1 h. After dropwise addition of benzyl bromide
(407 lL, 3.42 mmol), the reaction mixture was warmed
up to ꢀ30 °C, stirred for 3 h, quenched with saturated
NH4Cl, and extracted with EtOAc. The organic layer
was washed with brine and dried over Na2SO4. Removal
of the volatiles in vacuo provided a solid, which was
washed with Et2O–n-hexane to give 424 mg (82%) of
50 as a white powder: TLC Rf = 0.69 (EtOAc–n-hexane,
1:1); 1H NMR (200 MHz, DMSO-d6) d 8.53 (t,
J = 5.6 Hz, 1H), 7.84 (d, J = 8.4 Hz, 2H), 7.59 (d,
J = 8.4 Hz, 2H), 7.30–7.12 (m, 5H), 3.94 (q,
J = 7.0 Hz, 2H), 3.33–3.20 (m, 2H), 2.86–2.62 (m, 3H),
1.90–1.60 (m, 2H), 1.02 (t, J = 7.0 Hz, 3H).
1
(CHCl3–MeOH–H2O, 100:20:1); H NMR (200 MHz,
DMSO-d6)
d 8.61 (t, J = 5.4 Hz, 1H), 8.01 (d,
J = 8.8 Hz, 2H), 7.95 (d, J = 8.8 Hz, 2H), 7.70–7.63
(m, 2H), 7.57 (br s, 1H), 4.82 (d, J = 7.0 Hz, 1H), 4.77
(d, J = 7.0 Hz, 1H), 4.64 (d, J = 11.8 Hz, 1H), 4.54 (d,
J = 11.8 Hz, 1H), 4.13 (dd, J = 8.2, 4.2 Hz, 1H), 3.52–
3.28 (m, 2H), 2.12–1.82 (m, 2H).
4.33. (2R)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-2-
[(benzyloxy)methoxy]butanoic acid (47b)
The title compound was obtained as a white powder in
100% yield from 46b according to the same procedures
as described for the preparation of 29: TLC Rf = 0.45
1
(CHCl3–MeOH–H2O, 100:20:1); H NMR (200 MHz,
DMSO-d6)
d 8.61 (t, J = 5.4 Hz, 1H), 8.01 (d,
J = 8.8 Hz, 2H), 7.95 (d, J = 8.8 Hz, 2H), 7.70–7.63
(m, 2H), 7.57 (br s, 1H), 4.82 (d, J = 7.0 Hz, 1H), 4.77
(d, J = 7.0 Hz, 1H), 4.64 (d, J = 11.8 Hz, 1H), 4.54 (d,
J = 11.8 Hz, 1H), 4.13 (dd, J = 8.2, 4.2 Hz, 1H), 3.52–
3.28 (m, 2H), 2.12–1.82 (m, 2H).
4.37. Ethyl 4-{[4-(1-benzofuran-2-yl)benzoyl]amino}-2-
benzylbutanoate (51)
The title compound was obtained as an off-white pow-
der in 81% yield from 50 according to the same proce-
dures as described for the preparation of 26: TLC
4.34. 4-(1-Benzofuran-2-yl)-N-[(3S)-3-[(benzyloxy)meth-
oxy]-4-(hydroxyamino)-4-oxobutyl]benzamide (7)
1
Rf = 0.47 (EtOAc–n-hexane, 1:2); H NMR (200 MHz,
CDCl3): d 7.92 (d, J = 8.8 Hz, 2H), 7.82 (d, J = 8.8 Hz,
2H), 7.63–7.52 (m, 2H), 7.36–7.16 (m, 7H), 7.12 (br s,
1H), 6.41 (m, 1H), 4.05 (br q, J = 7.0 Hz, 2H), 3.62–
3.41 (m, 2H), 3.09–2.96 (m, 1H), 2.87–2.72 (m, 2H),
1.13 (t, J = 7.0 Hz, 3H).
The title compound was obtained as a white powder in
62% yield from 47a according to the same procedures
as described for the preparation of 2: TLC Rf = 0.24
(CHCl3–MeOH, 10:1); MS (APCI, neg. 40 V) m/z 473
(MꢀH)ꢀ; IR (KBr) 1627, 1539, 1497, 1450, 1310,
1
1108, 1065, 1032 cmꢀ1; H NMR (200 MHz, DMSO-
4.38. 4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-2-benzyl-
butanoic acid (52)
d6) d 10.75 (br s, 1H), 8.90 (br s, 1H), 8.55 (t,
J = 5.6 Hz, 1H), 8.01 (d, J = 8.8 Hz, 2H), 7.96 (d,
J = 8.8 Hz, 2H), 7.71–7.63 (m, 2H), 7.58 (br s, 1H),
7.39–7.24 (m, 7H), 4.77 (d, J = 7.0 Hz, 1H), 4.68 (d,
J = 7.0 Hz, 1H), 4.58 (s, 2H), 4.04 (t, J = 5.8 Hz, 1H),
The title compound was obtained as a white powder in
86% yield from 51 according to the same procedures as
described for the preparation of 29: TLC Rf = 0.37
(CHCl3–MeOH, 10:1); 1H NMR (200 MHz, DMSO-
d6) d 12.22 (br s, 1H), 8.58 (t, J = 5.6 Hz, 1H), 7.70–
7.63 (m, 2H), 7.57 (br s, 1H), 7.39–7.14 (m, 7H),
3.39–3.25 (m, 2H), 2.92–2.62 (m, 3H), 1.90–1.60 (m,
2H).
3.49–3.25 (m, 2H), 1.93 (q, J = 6.2 Hz, 2H); optical rota-
30
D
C27H27N2O6: 475.1869. Found: 475.1867.
tion ½aꢁ ꢀ27.0 (c 0.23, DMF); HRMS (FAB) calcd for
4.35. 4-(1-Benzofuran-2-yl)-N-[(3R)-3-[(benzyloxy)meth-
oxy]-4-(hydroxyamino)-4-oxobutyl]benzamide (8)
4.39. 4-(1-Benzofuran-2-yl)-N-[3-benzyl-4-(hydroxy-
amino)-4-oxobutyl]benzamide (9)
The title compound was obtained as a white powder in
61% yield from 47b according to the same procedures
as described for the preparation of 2: TLC Rf = 0.24
(CHCl3–MeOH, 10:1); MS (APCI, neg. 40 V) m/z 473
(MꢀH)ꢀ; IR (KBr) 1627, 1539, 1497, 1450, 1311,
The title compound was obtained as a white powder in
65% yield from 52 according to the same procedures as
described for the preparation of 2: TLC Rf = 0.39
(CHCl3–MeOH, 10:1); MS (MALDI, pos.) m/z 467
(M+K)+, 451 (M+Na)+, 429 (M+H)+; IR (KBr)
1655, 1636, 1607, 1560, 1497, 1451, 1308, 1257, 1200,
1
1108, 1065, 1031 cmꢀ1; H NMR (200 MHz, DMSO-
d6) d 10.75 (br s, 1H), 8.90 (br s, 1H), 8.55 (t,
J = 5.6 Hz, 1H), 8.01 (d, J = 8.8 Hz, 2H), 7.96 (d,
J = 8.8 Hz, 2H), 7.71–7.63 (m, 2H), 7.58 (br s, 1H),
7.39–7.24 (m, 7H), 4.77 (d, J = 7.0 Hz, 1H), 4.68 (d,
J = 7.0 Hz, 1H), 4.58 (s, 2H), 4.04 (t, J = 5.8 Hz, 1H),
1171, 1029 cmꢀ1 1H NMR (200 MHz, DMSO-d6) d
;
10.43 (s, 1H), 8.52 (t, J = 5.6 Hz, 1H), 8.00 (d,
J = 8.8 Hz, 2H), 7.94 (d, J = 8.8 Hz, 2H), 7.71–7.63
(m, 2H), 7.57 (s, 1H), 7.39–7.16 (m, 7H), 3.30–3.15
(m, 2H), 2.83 (dd, J = 13.6, 8.6 Hz, 1H), 2.66 (dd,
J = 13.6, 6.2 Hz, 1H), 2.44–2.31 (m, 1H), 1.88–1.53
3.49–3.25 (m, 2H), 1.93 (q, J = 6.2 Hz, 2H); optical rota-
30
D
C27H27N2O6: 475.1869. Found: 475.1872.
tion ½aꢁ +25.2 (c 0.23, DMF); HRMS (FAB) calcd for

5416
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
(m, 2H); HRMS (FAB) calcd for C26H25N2O4:
429.1814. Found: 429.1811.
4.43. 4-(1-Benzofuran-2-yl)-N-{3-[(hydroxyamino)car-
bonyl]-5-phenylpentyl}benzamide (10)
4.40. Ethyl 2-(cyanomethyl)-4-phenylbutanoate (54)
The title compound was obtained as a white powder in
59% yield from 57 according to the same procedures
as described for the preparation of 2: TLC Rf = 0.47
(CHCl3–MeOH, 10:1); MS (MALDI, pos.) m/z 481
(M+K)+, 465 (M+Na)+, 443 (M + H)+; IR (KBr)
To a stirred solution of ethyl 4-phenylbutanoate (53)
(500 mg, 2.60 mmol) in THF (10 mL) was added drop-
wise LDA (1.30 mL of a 2.0 M solution in THF,
2.60 mmol) at ꢀ78 °C. The reaction mixture was stirred
for 30 min, and bromoacetonitrile (362 lL, 5.20 mmol)
was added dropwise. After being stirred at ꢀ78 °C for
1 h, the reaction mixture was quenched with saturated
NH4Cl and extracted with EtOAc. The organic layer
was washed with water, brine and dried over Na2SO4.
Removal of the volatiles in vacuo provided an oily res-
idue, which was purified by silica gel chromatography
with EtOAc–n-hexane, 1:8, as an eluent. Evaporation
of the product-rich fractions provided 270 mg (45%) of
54: TLC Rf = 0.25 (EtOAc–n-hexane, 1:6); 1H NMR
(200 MHz, CDCl3) d 7.37–7.18 (m, 5H), 4.21 (q,
J = 7.0 Hz, 2H), 2.82–2.50 (m, 5H), 2.23–1.89 (m, 2H),
1.31 (t, J = 7.0 Hz, 3H).
1632, 1540, 1496, 1451, 1307, 1258, 1170, 1030 cmꢀ1
;
1H NMR (200 MHz, CD3OD) d 7.98 (d, J = 8.4 Hz,
2H), 7.89 (d, J = 8.4 Hz, 2H), 7.64–7.60 (m, 1H), 7.56–
7.52 (m, 1H), 7.36–7.09 (m, 7H), 7.32 (br s, 1H), 3.51–
3.24 (m, 2H), 2.68–2.50 (m, 2H), 2.28–2.14 (m, 1H),
2.04–1.69 (m, 4H); HRMS (FAB) calcd for
C27H27N2O4: 443.1971. Found: 443.1973.
4.44. Ethyl (4E)-2-{2-[(4-iodobenzoyl)amino]ethyl}-5-
phenyl-4-pentenoate (58)
To a stirred solution of ethyl 4-[(4-iodobenzoyl)ami-
no]butanoate (49) (800 mg, 2.21 mmol) in THF
(20 mL) was added dropwise LiHMDS (4.86 mL of a
1.0 M solution in THF, 4.86 mmol) at ꢀ78 °C. The reac-
tion mixture was stirred for 1 h and 1-bromo-3-phenyl-
2-propene (1.31 g, 6.63 mmol) was added dropwise.
The reaction mixture was warmed up to ꢀ40 °C, stirred
for 2 h, quenched with saturated NH4Cl, and extracted
with EtOAc. The organic layer was washed with water,
brine and dried over Na2SO4. Removal of the volatiles
in vacuo provided a solid, which was washed with
Et2O–n-hexane to give 700 mg (67%) of 58 as a white
powder: TLC Rf = 0.44 (EtOAc–n-hexane, 1:2); 1H
NMR (200 MHz, CDCl3) d 7.78 (d, J = 8.7 Hz, 2H),
7.49 (d, J = 8.7 Hz, 2H), 7.38–7.15 (m, 5H), 6.43 (d,
J = 15.6 Hz, 1H), 6.39 (br s, 1H), 6.12 (dt, J = 15.6,
6.9 Hz, 1H), 4.21–4.02 (m, 2H), 3.62–3.40 (m, 2H),
2.70–2.38 (m, 3H), 2.05–1.82 (m, 2H), 1.21 (t,
J = 7.2 Hz, 3H).
4.41. Ethyl 4-amino-2-(2-phenylethyl)butanoate hydro-
chloride (55) and ethyl 4-{[4-(1-benzofuran-2-yl)benzo-
yl]amino}-2-(2-phenylethyl)butanoate (56)
Catalytic hydrogenation of 54 (218 mg, 0.943 mmol) in
MeOH-4 N HCl/EtOAc (15 mL-0.71 mL) was conduct-
ed for 1.5 h at room temperature in the presence of
10% PtO2 (10 mg) at an atmospheric pressure. Removal
of the catalyst by filtration, followed by evaporation of
the solvent, provided 55 as an oily residue. To a stirred
solution of 55 (0.943 mmol) in CH2Cl2 (10 mL) were
added triethylamine (525 lL, 3.77 mmol) at 0 °C and
then 4-(1-benzofuran-2-yl)benzoyl chloride (43) (242 mg,
0.943 mmol). After being stirred at room temperature
for 30 min, the reaction mixture was poured into 1 N
HCl and extracted with EtOAc. The organic layer was
washed with water, brine and dried over Na2SO4.
Removal of the volatiles in vacuo provided an oily
residue, which was purified by silica gel chromatography
using EtOAc–n-hexane, 1:3, as an eluent. Evaporation
of the product-rich fractions provided 212 mg (49%
in two steps) of 56 as a white powder: TLC Rf = 0.71
(EtOAc–n-hexane, 1:1); 1H NMR (200 MHz, CDCl3)
d 7.92 (d, J = 8.8 Hz, 2H), 7.82 (d, J = 8.8 Hz, 2H),
7.63–7.52 (m, 2H), 7.36–7.15 (m, 7H), 7.12 (br s,
1H), 4.15 (q, J = 7.0 Hz, 2H), 3.65–3.38 (m, 2H),
2.68–2.45 (m, 3H), 2.15–1.74 (m, 4H), 1.26 (t, J =
7.0 Hz, 3H).
4.45. Ethyl (4E)-2-(2-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}ethyl)-5-phenyl-4-pentenoate (59)
The title compound was obtained as a gray powder in
95% yield from 58 according to the same procedures
as described for the preparation of 26: TLC Rf = 0.38
1
(EtOAc–n-hexane, 1:2); H NMR (200 MHz, CDCl3) d
7.92 (d, J = 8.8 Hz, 2H), 7.85 (d, J = 8.8 Hz, 2H),
7.63–7.52 (m, 2H), 7.36–7.21 (m, 7H), 7.12 (d,
J = 0.8 Hz, 1H), 6.49 (t, J = 5.2 Hz, 1H), 6.45 (d,
J = 15.8 Hz, 1H), 6.13 (dt, J = 15.8, 7.2 Hz, 1H), 4.21–
4.05 (m, 2H), 3.66–3.45 (m, 2H), 2.70–2.43 (m, 3H),
2.09–1.85 (m, 2H), 1.22 (t, J = 7.4 Hz, 3H).
4.42. 4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-2-(2-phen-
ylethyl)butanoic acid (57)
4.46. Ethyl 2-(2-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}ethyl)-5-phenylpentanoate (60)
The title compound was obtained as a white powder in
88% yield from 56 according to the same procedures
as described for the preparation of 29: TLC Rf = 0.42
(CHCl3–MeOH, 10:1); (200 MHz, DMSO-d6) d 8.57
(br t, J = 5.6 Hz, 1H), 8.01 (d, J = 8.8 Hz, 2H), 7.95
(d, J = 8.8 Hz, 2H), 7.71–7.63 (m, 2H), 7.58 (br s, 1H),
7.40–7.12 (m, 7H), 3.35–3.25 (m, 2H), 2.57 (t,
J = 7.8 Hz, 2H), 2.42–2.28 (m, 1H), 1.94–1.65 (m, 4H).
Catalytic hydrogenation of 59 (300 mg, 0.642 mmol) in
MeOH (10 mL) and DMF (0.5 mL) was conducted at
room temperature for 30 min in the presence of 10% pal-
ladium on carbon (30 mg) at an atmospheric pressure.
The catalyst was removed by filtration and the volatiles
were removed in vacuo. The resulting residue was dilut-
ed with water and extracted with EtOAc. The organic

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5417
layer was washed with brine and dried over Na2SO4.
Removal of the volatiles in vacuo provided 300 mg
(99%) of 60 as a white powder: TLC Rf = 0.33
7.80 (d, J = 8.4 Hz, 2H), 7.36 (d, J = 8.4 Hz, 2H),
4.32–4.18 (m, 1H), 4.05 (d, J = 5.2 Hz, 2H), 3.70 (s,
3H), 3.03 (br s, 1H), 2.57–2.53 (m, 2H), 2.46 (s, 3H);
30
1
(EtOAc–n-hexane, 1:2); H NMR (200 MHz, CDCl3) d
optical rotation ½aꢁ ꢀ7.23 (c 0.59, CHCl3).
D
7.93 (d, J = 8.8 Hz, 2H), 7.84 (d, J = 8.8 Hz, 2H),
7.63–7.52 (m, 2H), 7.36–7.13 (m, 7H), 7.12 (br s, 1H),
4.12 (br q, J = 6.8 Hz, 2H), 3.63–3.36 (m, 2H), 2.62 (t,
J = 6.8 Hz, 2H), 2.56–2.44 (m, 1H), 2.05–1.50 (m, 6H),
1.23 (t, J = 6.8 Hz, 3H).
4.50. Methyl (3R)-3,4-dihydroxybutanoate (63b) and
methyl (3R)-3-hydroxy-4-{[(4-methylphenyl)sulfo-
nyl]oxy}butanoate (64b)
The diol 63b was obtained quantitatively from 62b as a
yellow oil according to the same procedures as described
for the preparation of 63a: TLC Rf = 0.25 (EtOAc). The
tosylate 64b was obtained as a brown solid in 50% yield
from 63b according to the same procedures as described
for the preparation of 40a: TLC Rf = 0.17 (EtOAc–n-
4.47. 2-(2-{[4-(1-Benzofuran-2-yl)benzoyl]amino}ethyl)-5-
phenylpentanoic acid (61)
The title compound was obtained as a white powder in
96% yield from 60 according to the same procedures
as described for the preparation of 29: TLC Rf = 0.45
(CHCl3–MeOH, 10:1); 1H NMR (200 MHz, DMSO-
d6) d 12.18 (br s, 1H), 8.55 (t, J = 5.4 Hz, 1H), 7.71–
7.62 (m, 2H), 7.57 (br s, 1H), 7.39–7.11 (m, 7H), 3.31–
3.22 (m, 2H), 2.61–2.53 (m, 2H), 2.46–2.28 (m, 1H),
1.89–1.46 (m, 8H).
1
hexane, 1:2); H NMR (200 MHz, CDCl3) d 7.80 (d,
J = 8.4 Hz, 2H), 7.36 (d, J = 8.4 Hz, 2H), 4.32–4.18
(m, 1H), 4.05 (d, J = 5.2 Hz, 2H), 3.70 (s, 3H), 3.03
(br s, 1H), 2.57–2.53 (m, 2H), 2.46 (s, 3H); optical rota-
30
D
tion ½aꢁ +5.46 (c 0.505, CHCl3).
4.51. Methyl (3S)-4-azido-3-hydroxybutanoate (65a)
4.48. 4-(1-Benzofuran-2-yl)-N-{3-[(hydroxyamino)car-
bonyl]-6-phenylhexyl}benzamide (11)
The title compound was obtained as a yellow oil in 77%
yield from 64a according to the same procedures as de-
scribed for the preparation of 41a: TLC Rf = 0.68
The title compound was obtained as a white powder in
80% yield from 61 according to the same procedures
as described for the preparation of 2: TLC Rf = 0.41
(CHCl3–MeOH, 10:1); MS (MALDI, pos.) m/z 495
(M+K)+, 479 (M+Na)+, 457 (M+H)+; IR (KBr) 1634,
1
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, CDCl3) d
4.28–4.14 (m, 1H), 3.74 (s, 3H), 3.40 (dd, J = 9.6,
3.1 Hz, 1H), 3.33 (dd, J = 9.6, 4.1 Hz, 1H), 3.14 (d,
J = 4.0 Hz, 1H), 2.58–2.55 (m, 2H).
1542, 1497, 1451, 1307, 1258, 1170, 1031 cmꢀ1 1H
;
NMR (200 MHz, DMSO-d6) d 10.48 (s, 1H), 8.50 (t,
J = 5.6 Hz, 1H), 8.01 (d, J = 8.8 Hz, 2H), 7.95 (d,
J = 8.8 Hz, 2H), 7.71–7.63 (m, 2H), 7.57 (s, 1H), 7.39–
7.11 (m, 7H), 3.25–3.15 (m, 2H), 2.59–2.47 (m, 2H),
2.18–2.02 (m, 1H), 1.82–1.36 (m, 6H); HRMS (FAB)
calcd for C28H29N2O4: 457.2127. Found: 457.2122.
4.52. Methyl (3R)-4-azido-3-hydroxybutanoate (65b)
The title compound was obtained as a yellow oil in 84%
yield from 64b according to the same procedures as de-
scribed for the preparation of 41a: TLC Rf = 0.68
1
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, CDCl3) d
4.28–4.14 (m, 1H), 3.74 (s, 3H), 3.40 (dd, J = 9.6,
3.1 Hz, 1H), 3.33 (dd, J = 9.6, 4.1 Hz, 1H), 3.14 (d,
J = 4.0 Hz, 1H), 2.58–2.55 (m, 2H).
4.49. Methyl (3S)-3,4-dihydroxybutanoate (63a) and
methyl (3S)-3-hydroxy-4-{[(4-methylphenyl)sulfo-
nyl]oxy}butanoate (64a)
4.53. Methyl (3S)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-3-hydroxybutanoate (66a)
To a stirred solution of dimethyl (2S)-2-hydroxysucci-
nate (62a) (15.0 g, 92.5 mmol) in THF (170 mL) were
added dropwise borane–methyl sulfide complex
(7.24 g, 95.3 mmol) at room temperature and then sodi-
um borohydride (175 mg, 4.63 mmol) in one portion at
0 °C. After being stirred at 0 °C for 10 min, the reaction
mixture was warmed up to room temperature and stir-
red for 30 min. To the stirred reaction mixture were add-
ed MeOH (40 mL) and p-toluenesulfonic acid
monohydrate (797 mg, 4.63 mmol) at room tempera-
ture. After being stirred for 30 min, the reaction mixture
was evaporated. The resulting residue was diluted with
MeOH–benzene and the resulting solution was evapo-
rated again. This operation was repeated several times.
Dilution of the resulting residue with benzene followed
by removal of the volatiles in vacuo provided 13.0 g
(100%) of 63a as a yellow oil: TLC Rf = 0.25 (EtOAc).
The tosylate 64a was obtained as a brown solid in
48% yield from 63a according to the same procedures
as described for the preparation of 40a: TLC Rf = 0.17
The title compound was obtained as a beige powder in
84% yield from 65a according to the same procedures
as described for the preparation of 44a: TLC Rf = 0.31
1
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, DMSO-
d6) d 8.57 (t, J = 6.0 Hz, 1H), 8.00 (m, 4H), 7.71–7.63
(m, 2H), 7.57 (br s, 1H), 7.40–7.24 (m, 2H), 5.13 (d,
J = 5.6 Hz, 1H), 4.18–4.00 (m, 1H), 3.57 (s, 3H), 3.30
(t, J = 6.0 Hz, 2H), 2.55 (dd, J = 15.0, 4.0 Hz, 1H),
2.31 (dd, J = 15.0, 4.0 Hz, 1H).
4.54. Methyl (3R)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-3-hydroxybutanoate (66b)
The title compound was obtained as a beige powder in
74% yield from 65b according to the same procedures
as described for the preparation of 44a: TLC Rf = 0.31
1
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, DMSO-
d6) d 8.57 (t, J = 6.0 Hz, 1H), 8.00 (m, 4H), 7.71–7.63
(m, 2H), 7.57 (br s, 1H), 7.40–7.24 (m, 2H), 5.13 (d,
1
(EtOAc–n-hexane, 1:2); H NMR (200 MHz, CDCl3) d

5418
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
J = 5.6 Hz, 1H), 4.18–4.00 (m, 1H), 3.57 (s, 3H), 3.30 (t,
J = 6.0 Hz, 2H), 2.55 (dd, J = 15.0, 4.0 Hz, 1H), 2.31
(dd, J = 15.0, 4.0 Hz, 1H).
4.59. Methyl (3S)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-3-(methoxymethoxy)butanoate (68a)
To a stirred solution of 66a (200 mg, 0.566 mmol) in
CH2Cl2 (1 mL) were added N,N-diisopropylethylamine
(1 mL) and methoxymethyl chloride (220 lL, 2.83 mmol)
at 0 °C. After being stirred at room temperature over-
night, the reaction mixture was poured into 0.5 N HCl
and extracted with EtOAc. The organic layer was washed
with water, brine and dried over Na2SO4. Removal of the
volatiles in vacuo provided an oily residue, which was
purified by silica gel chromatography with EtOAc–n-hex-
ane, 1:1, as an eluent. Evaporation of the product-rich
fractions provided 175 mg (78%) of 68a as a white pow-
4.55. (3S)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-3-
hydroxybutanoic acid (67a)
The title compound was obtained as a beige powder in
84% yield from 66a according to the same procedures
as described for the preparation of 29: TLC Rf = 0.24
(CHCl3–MeOH–AcOH,
100:10:1);
1H
NMR
(200 MHz, DMSO-d6) d 8.55 (t, J = 5.8 Hz, 1H), 7.71–
7.63 (m, 2H), 7.58 (br s, 1H), 7.39–7.23 (m, 2H), 5.16–
4.92 (br s, 1H), 4.14–4.00 (m, 1H), 3.30 (t, J = 5.8 Hz,
2H), 2.46 (dd, J = 15.0, 4.2 Hz, 1H), 2.23 (dd, J = 15.0,
8.4 Hz, 1H).
1
der: TLC Rf = 0.38 (EtOAc–n-hexane, 1:1); H NMR
(200 MHz, DMSO-d6) d 8.65 (t, J = 5.4 Hz, 1H), 8.02
(d, J = 9.2 Hz, 2H), 7.97 (d, J = 9.2 Hz, 2H), 7.71–7.63
(m, 2H), 7.57 (br s, 1H), 7.40–7.24 (m, 2H), 4.65 (d,
J = 7.0 Hz, 1H), 4.59 (d, J = 7.0 Hz, 1H), 4.20–4.08 (m,
1H), 3.58 (s, 3H), 3.52–3.34 (m, 2H), 2.65 (dd, J = 15.8,
4.4 Hz, 1H), 2.54–2.43 (m, 1H).
4.56. (3R)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-3-
hydroxybutanoic acid (67b)
The title compound was obtained as a beige powder in
88% yield from 66b according to the same procedures
as described for the preparation of 29: TLC Rf = 0.24
4.60. Methyl (3R)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-3-(methoxymethoxy)butanoate (68b)
(CHCl3–MeOH–AcOH,
100:10:1);
1H
NMR
(200 MHz, DMSO-d6) d 8.55 (t, J = 5.8 Hz, 1H), 7.71–
7.63 (m, 2H), 7.58 (br s, 1H), 7.39–7.23 (m, 2H), 5.16–
4.92 (br s, 1H), 4.14–4.00 (m, 1H), 3.30 (t, J = 5.8 Hz,
2H), 2.46 (dd, J = 15.0, 4.2 Hz, 1H), 2.23 (dd, J = 15.0,
8.4 Hz, 1H).
The title compound was obtained as a white powder in
75% yield from 66b according to the same procedures as
described for the preparation of 68a: TLC Rf = 0.38
1
(EtOAc–n-hexane, 1:1); H NMR (200 MHz, DMSO-
d6) d 8.65 (t, J = 5.4 Hz, 1H), 8.02 (d, J = 9.2 Hz, 2H),
7.97 (d, J = 9.2 Hz, 2H), 7.71–7.63 (m, 2H), 7.57 (br s,
1H), 7.40–7.24 (m, 2H), 4.65 (d, J = 7.0 Hz, 1H), 4.59
(d, J = 7.0 Hz, 1H), 4.20–4.08 (m, 1H), 3.58 (s, 3H),
3.52–3.34 (m, 2H), 2.65 (dd, J = 15.8, 4.4 Hz, 1H), 2.54–
2.43 (m, 1H).
4.57. 4-(1-Benzofuran-2-yl)-N-[(2S)-2-hydroxy-4-
(hydroxyamino)-4-oxobutyl]benzamide (12)
The title compound was obtained as a white powder in
70% yield from 67a according to the same procedures
as described for the preparation of 2: TLC Rf = 0.41
(CHCl3–MeOH–H2O, 100:20:1); MS (MALDI, pos.)
m/z 377 (M+Na)+, 355 (M+H)+; IR (KBr) 1636, 1541,
4.61. (3S)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-3-
(methoxymethoxy)butanoic acid (69a)
1497, 1450, 1308, 1082 cmꢀ1 1H NMR (200 MHz,
;
DMSO-d6) d 10.39 (br s, 1H), 8.55 (m, 1H), 8.00 (s,
4H), 7.71–7.63 (m, 2H), 7.57 (br s, 1H), 7.39–7.23 (m,
2H), 5.50–4.30 (br, 1H), 4.12–3.98 (m, 1H), 3.40–3.18
The title compound was obtained quantitatively from 68a
as a pale yellow powder according to the same procedures
as described for the preparation of 29: TLC Rf = 0.21
1
(m, 2H), 2.16 (dd, J = 14.0, 4.8 Hz, 1H), 2.03 (dd,
(CHCl3–MeOH, 10:1); H NMR (200 MHz, DMSO-d6)
30
D
J = 14.0, 8.2 Hz, 1H); optical rotation ½aꢁ ꢀ4.95 (c
d 8.64 (t, J = 5.6 Hz, 1H), 8.00 (s, 4H), 7.71–7.63 (m,
2H), 7.57 (br s, 1H), 7.39–7.23 (m, 2H), 4.64 (s, 2H),
4.08 (m, 1H), 3.44 (m, 2H), 3.24 (s, 3H), 2.22 (m, 2H).
0.42, DMF); HRMS (FAB) calcd for C19H19N2O5:
355.1294. Found: 355.1290.
4.58. 4-(1-Benzofuran-2-yl)-N-[(2R)-2-hydroxy-4-
(hydroxyamino)-4-oxobutyl]benzamide (13)
4.62. (3R)-4-{[4-(1-benzofuran-2-yl)benzoyl]amino}-3-
(methoxymethoxy)butanoic acid (69b)
The title compound was obtained as a white powder in
53% yield from 67b according to the same procedures
as described for the preparation of 2: TLC Rf = 0.41
(CHCl3–MeOH–H2O, 100:20:1); MS (MALDI, pos.)
m/z 355 (M+H)+; IR (KBr) 1635, 1541, 1497, 1450,
The title compound was obtained quantitatively from 68b
as a pale yellow powder according to the same procedures
as described for the preparation of 29: TLC Rf = 0.21
1
(CHCl3–MeOH, 10:1); H NMR (200 MHz, DMSO-d6)
d 8.64 (t, J = 5.6 Hz, 1H), 8.00 (s, 4H), 7.71–7.63 (m,
2H), 7.57 (br s, 1H), 7.39–7.23 (m, 2H), 4.64 (s, 2H),
4.08 (m, 1H), 3.44 (m, 2H), 3.24 (s, 3H), 2.22 (m, 2H).
1307, 1172, 1083, 1034 cmꢀ1 1H NMR (200 MHz,
;
DMSO-d6) d 10.39 (br s, 1H), 8.55 (t, J = 5.4 Hz, 1H),
8.00 (s, 4H), 7.71–7.63 (m, 2H), 7.58 (br s, 1H), 7.39–
7.24 (m, 2H), 5.20–3.80 (br, 1H), 4.12–3.98 (m, 1H),
3.40–3.18 (m, 2H), 2.16 (dd, J = 14.0, 4.8 Hz, 1H),
4.63. 4-(1-Benzofuran-2-yl)-N-[(2S)-4-(hydroxyamino)-2-
(methoxymethoxy)-4-oxobutyl]benzamide (14)
2.03 (dd, J = 14.0, 8.2 Hz, 1H); optical rotation
30
D
C19H19N2O5: 355.1294. Found: 355.1290.
½aꢁ +3.76 (c 0.41, DMF); HRMS (FAB) calcd for
The title compound was obtained as a white powder
in 27% yield from 69a according to the same

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5419
procedures as described for the preparation of 2:
4.67. (4S)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-5-
hydroxypentanoic acid (73)
TLC Rf = 0.19 (CHCl3–MeOH, 10:1); MS (MALDI,
pos.) m/z 421 (M+Na)+, 399 (M+H)+; IR (KBr)
1638, 1539, 1497, 1450, 1306, 1151, 1099,
The title compound was obtained as a pale pink powder in
89% yield from 72 according to the same procedures as de-
scribed for the preparation of 29: TLC Rf = 0.33 (CHCl3–
MeOH–AcOH, 190:10:1); 1H NMR (200 MHz, DMSO-d6)
d 12.10–11.90 (br, 1H), 8.14 (d, J = 8.8 Hz, 1H), 8.00 (s,
4H), 7.73–7.60 (m, 2H), 7.55 (s, 1H), 7.41–7.22 (m, 2H),
4.58 (s, 2H), 4.80–4.64 (m, 1H), 4.10–3.90 (m, 1H), 3.54–
3.35 (m, 2H), 2.28 (t, J = 6.8 Hz, 2H), 2.02–1.60 (m, 2H).
1031 cmꢀ1 1H NMR (200 MHz, DMSO-d6) d 10.47
;
(br s, 1H), 8.80 (br s, 1H), 8.64 (t, J = 5.8 Hz,
1H), 8.02 (d, J = 9.2 Hz, 2H), 7.97 (d, J = 9.2 Hz,
2H), 7.71–7.63 (m, 2H), 7.57 (br s, 1H), 7.40–7.24
(m, 2H), 4.60 (s, 2H), 4.16–4.05 (m, 1H), 3.41 (t,
J = 5.8 Hz., 2H), 3.21 (s, 3H), 2.22–2.18 (m, 2H);
HRMS (FAB) calcd for C21H23N2O6: 399.1556.
Found: 399.1556.
4.68. 4-(1-Benzofuran-2-yl)-N-[(1S)-4-(hydroxyamino)-1-
(hydroxymethyl)-4-oxobutyl]benzamide (16)
4.64. 4-(1-Benzofuran-2-yl)-N-[(2R)-4-(hydroxyamino)-2-
(methoxymethoxy)-4-oxobutyl]benzamide (15)
The title compound was obtained as a white powder in
32% yield from 73 according to the same procedures
as described for the preparation of 2: TLC Rf = 0.22
(CHCl3–MeOH, 9:1); MS (FAB, pos.) m/z 369
(M+H)+; IR (KBr) 3256, 1634, 1542, 1497, 1450, 1350,
The title compound was obtained as a white powder in
19% yield from 69b according to the same procedures
as described for the preparation of 2: TLC Rf = 0.19
(CHCl3–MeOH, 10:1); MS (MALDI, pos.) m/z 421
(M+Na)+, 399 (M+H)+; IR (KBr) 1638, 1536, 1496,
1172, 1110, 1033, 979 cmꢀ1
;
1H NMR (200 MHz,
1450, 1297, 1149, 1113, 1027 cmꢀ1
;
1H NMR
DMSO-d6) d 10.36 (d, J = 1.5 Hz, 1H), 8.67 (d,
J = 1.5 Hz, 1H), 8.19 (d, J = 8.4 Hz, 1H), 8.00 (s, 4H),
7.73–7.61 (m, 2H), 7.57 (d, J = 0.8 Hz, 1H), 7.42–7.23
(m, 2H), 4.73 (t, J = 5.8 Hz, 1H), 4.08–3.85 (m, 1H),
(200 MHz, DMSO-d6) d 10.46 (br s, 1H), 8.77 (br s,
1H), 8.64 (t, J = 5.8 Hz, 1H), 8.02 (d, J = 9.2 Hz, 2H),
7.97 (d, J = 9.2 Hz, 2H), 7.71–7.63 (m, 2H), 7.58 (br s,
1H), 7.40–7.24 (m, 2H), 4.60 (s, 2H), 4.16–4.05 (m,
1H), 3.42 (t, J = 5.8 Hz, 2H), 3.22 (s, 3H), 2.22–2.19
(m, 2H); HRMS (FAB) calcd for C21H23N2O6:
399.1556. Found: 399.1555.
3.58–3.38 (m, 2H), 2.12–1.60 (m, 4H); optical rotation
30
D
C20H21N2O5: 369.1450. Found: 369.1447.
½aꢁ ꢀ52.52 (c 0.50, DMF); HRMS (FAB) calcd for
4.69. Methyl (4S)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-5-(methoxymethoxy)pentanoate (74)
4.65. (2S)-2-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-5-
methoxy-5-oxopentanoic acid (71)
The title compound was obtained quantitatively from 72
as a beige powder according to the same procedures as
described for the preparation of 68a: TLC Rf = 0.65
To a stirred solution of 4-(1-benzofuran-2-yl)benzoyl
chloride (43) (5.00 g, 19.5 mmol) in THF (30 mL) were
added c-methyl L-glutamate (70) (3.46 g, 21.5 mmol),
NaHCO3 powder (5.00 g, 58.5 mmol), and water
(20 mL). After being stirred at room temperature over-
night, the reaction mixture was acidified with 1 N HCl
and extracted with EtOAc. The organic layer was
washed with brine and dried over MgSO4. Removal of
the volatiles in vacuo provided a solid, which was
washed with CHCl3–n-hexane to give 6.07 g (82%) of
71 as a pale yellow powder: TLC Rf = 0.60 (CHCl3–
MeOH–AcOH, 18:2:1); MS (MALDI, pos.) m/z 404
1
(EtOAc–n-hexane, 7:3); H NMR (200 MHz, CDCl3) d
7.94 (d, J = 8.8 Hz, 2H), 7.87 (d, J = 8.8 Hz, 2H),
7.64–7.50 (m, 2H), 7.38–7.21 (m, 2H), 7.13 (d,
J = 0.8 Hz, 1H), 6.78 (d, J = 7.8 Hz, 1H), 4.67 (s, 2H),
4.46–4.28 (m, 1H), 3.78 (dd, J = 10.2, 3.4 Hz, 1H),
3.65 (dd, J = 10.2, 4.4 Hz, 1H), 3.64 (s, 3H), 3.39 (s,
3H), 2.62–2.38 (m, 2H), 2.16–2.00 (m, 2H).
4.70. (4S)-4-{[4-(1-Benzofuran-2-yl)benzoyl]amino}-5-
(methoxymethoxy)pentanoic acid (75)
1
(M+Na)+, 382 (M+H)+; H NMR (200 MHz, DMSO-
d6) d 12.74 (br s, 1H), 8.74 (d, J = 7.8 Hz, 1H), 8.06–
8.01 (m, 4H), 7.71–7.58 (m, 3H), 7.42–7.26 (m, 2H),
4.51–4.38 (m, 1H), 3.60 (s, 3H), 2.51–2.44 (m,2H),
2.26–1.96 (m, 2H).
The title compound was obtained quantitatively from 74
as a white powder according to the same procedures as de-
scribed for the preparation of 29: TLC Rf = 0.13 (EtOAc–
1
n-hexane, 7:3); H NMR (200 MHz, DMSO-d6) d 12.02
(s, 1H), 8.30 (d, J = 8.2 Hz, 1H), 8.00 (s, 4H), 7.73–7.60
(m, 2H), 7.56 (s, 1H), 7.41–7.22 (m, 2H), 4.58 (s, 2H),
4.26–4.08 (m, 1H), 3.62–3.42 (m, 2H), 3.32 (s, 3H), 3.26
(s, 3H), 2.29 (t, J = 6.8 Hz, 2H), 2.02–1.60 (m, 2H).
4.66. Methyl (4S)-4-{[4-(1-benzofuran-2-yl)benzoyl]ami-
no}-5-hydroxypentanoate (72)
The title compound was obtained as a white powder in
34% yield from 71 according to the same procedures
as described for the preparation of 39a: TLC Rf = 0.47
4.71. 4-(1-Benzofuran-2-yl)-N-{(1S)-4-(hydroxyamino)-1-
[(methoxymethoxy)methyl]-4-oxobutyl}benzamide (17)
1
(EtOAc–n-hexane, 7:3); H NMR (200 MHz, DMSO-
d6) d 8.14 (d, J = 8.4 Hz, 1H), 7.99 (s, 4H), 7.72–7.60
(m, 2H), 7.55 (d, J = 0.8 Hz, 1H), 7.40–7.24 (m, 2H),
4.75 (t, J = 5.8 Hz, 1H), 4.10–3.90 (m, 1H), 3.56 (s,
3H), 3.55–3.39 (m, 2H), 2.36 (t, J = 7.4 Hz, 2H), 2.06–
1.62 (m, 2H).
The title compound was obtained as a white powder in
69% yield from 75 according to the same procedures
as described for the preparation of 2: TLC Rf = 0.47
(CHCl3–MeOH, 9:1); MS (APCI, neg. 40 V) m/z 411
(MꢀH)ꢀ; IR (KBr) 1634, 1539, 1497, 1450, 1308,

5420
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
1150, 1111, 1041 cmꢀ1; 1H NMR (200 MHz, DMSO-d6)
d 10.37 (s, 1H), 8.34 (d, J = 8.4 Hz, 1H), 8.00 (s, 4H),
7.73–7.61 (m, 2H), 7.56 (s, 1H), 7.41–7.24 (m, 2H),
4.58 (s, 2H), 4.23–4.04 (m, 1H), 3.62–3.44 (m, 2H),
as described for the preparation of 78a. Purification
was performed by silica gel chromatography with
EtOAc–toluene, 4:6, as an eluent: TLC Rf = 0.36 (tolu-
1
ene–EtOAc, 1:1); H NMR (200 MHz, CDCl3) d 7.81–
3.26 (s, 3H), 2.12–1.62 (m, 4H); optical rotation
½aꢁ ꢀ40.52 (c 0.575, DMF); HRMS (FAB) calcd for
7.74 (m, 2H), 7.55–7.48 (m, 2H), 6.91 (d, J = 7.0 Hz,
1H), 4.21–4.05 (m, 1H), 3.75–3.70 (m, 2H), 3.65 (s,
3H), 2.88 (t, J = 5.0 Hz, 1H), 2.53–2.45 (m, 2H), 2.04–
1.94 (m, 2H).
30
D
C22H25N2O6: 413.1713. Found: 413.1712.
4.72. (2S)-2-[(4-Iodobenzoyl)amino]-5-methoxy-5-oxo-
pentanoic acid (77a)
4.76. Methyl (4S)-5-hydroxy-4-{[4-(3-methoxy-1-
propynyl)benzoyl]amino}pentanoate (79a)
To a stirred mixture of 70 (25.0 g, 155 mmol), NaHCO3
powder (33.0 g, 388 mmol) in Et2O–H2O (1:1, 400 mL)
was added dropwise 4-iodobenzoyl chloride (43.4 g,
163 mmol) at 0 °C. After being stirred at room tempera-
ture overnight, the reaction mixture was acidified with 2 N
HCl and extracted with EtOAc. The organic layer was
washed with water, brine, and dried over MgSO4. Removal
of the volatiles in vacuo provided a crude solid, which was
washed with toluene to give 58.1 g (96%) of 77a as a white
To a stirred solution of 78a (3.00 g, 7.96 mmol) in
DMF (20 mL) and triethylamine (20 mL) were added
3-methoxy-1-propyne (2.00 mL, 23.9 mmol), tetra-
kis(triphenylphosphine)palladium(0) (370 mg, 0.318
mmol), and copper(I) iodide (60 mg, 0.318 mmol).
After being stirred at room temperature for 5 h, the
reaction mixture was diluted with saturated NH4Cl
and extracted with EtOAc. The organic layer was
washed with brine and dried over MgSO4. Removal
of the volatiles in vacuo provided an oily residue, which
was purified by silica gel chromatography with MeOH–
CHCl3, 1:30, as an eluent. Evaporation of the product-
rich fractions provided 1.82 g (72%) of 79a as a pale
yellow powder: TLC Rf = 0.39 (CHCl3–MeOH, 9:1);
MS (MALDI, pos.) m/z 358 (M+K)+, 342 (M+Na)+,
1
powder: TLC Rf = 0.30 (CHCl3–MeOH, 8:2); H NMR
(300 MHz, DMSO-d6) d 8.67 (d, J = 7.8 Hz, 1H), 7.87–
7.84 (m, 2H), 7.67–7.63 (m, 2H), 4.40–4.32 (m, 1H), 3.65
(s, 3H), 2.44–2.39 (m, 2H), 2.18–1.89 (m, 2H).
4.73. (2R)-2-[(4-Iiodobenzoyl)amino]-5-methoxy-5-oxo-
pentanoic acid (77b)
1
320 (M+H)+; H NMR (200 MHz, CDCl3) d 7.76 (d,
The title compound was obtained as a white powder in
66% yield from 76 according to the same procedures
as described for the preparation of 77a: TLC Rf = 0.30
J = 8.2 Hz, 2H), 7.51 (d, J = 8.2 Hz, 2H), 6.88 (d,
J = 8.0 Hz, 1H), 4.34 (s, 2H), 4.24–4.08 (m, 1H),
3.78–3.70 (m, 2H), 3.66 (s, 3H), 3.46 (s, 3H), 2.91 (t,
J = 5.7 Hz, 1H), 2.55 (m, 2H), 2.01 (q, J = 6.9 Hz, 2H).
1
(CHCl3–MeOH, 8:2); H NMR (300 MHz, DMSO-d6)
d 8.67 (d, J = 7.8 Hz, 1H), 7.87–7.84 (m, 2H), 7.67–
7.63 (m, 2H), 4.40–4.32 (m, 1H), 3.65 (s, 3H), 2.44–
2.39 (m, 2H), 2.18–1.89 (m, 2H).
4.77. Methyl (4R)-5-hydroxy-4-{[4-(3-methoxy-1-
propynyl)benzoyl]amino}pentanoate (79b)
4.74. Methyl (4S)-5-hydroxy-4-[(4-iodobenzoyl)ami-
no]pentanoate (78a)
To a stirred solution of 78b (1.50 g, 4.59 mmol) in DMF
(9 mL) and triethylamine (4.5 mL) were added 3-meth-
oxy-1-propyne (482 mg, 6.89 mmol) and dichlorobis(tri-
phenylphosphine)palladium(II) (161 mg, 0.23 mmol).
After being stirred at room temperature for 3 h, the
reaction mixture was diluted with 1 N HCl and extract-
ed with EtOAc. The organic layer was washed with
brine and dried over MgSO4. Removal of the volatiles
in vacuo provided an oily residue, which was purified
by silica gel chromatography with toluene–EtOAc, 3:7,
as an eluent. Evaporation of the product-rich fractions
provided 1.04 g (71%) of 79b as an off-white powder:
TLC Rf = 0.41 (toluene–EtOAc, 9:1); 1H NMR
(200 MHz, CDCl3) d 7.76 (d, J = 8.4 Hz, 2H), 7.50 (d,
J = 8.4 Hz, 2H), 6.86 (d, J = 8.0 Hz, 1H), 4.23 (s, 2H),
4.19–4.09 (m, 1H), 3.73–3.71 (m, 2H), 3.65 (s, 3H),
3.46 (s, 3H), 2.54–2.45 (m, 2H), 2.05–1.95 (m, 2H).
To a stirred solution of 77a (58.0 g, 148 mmol) in THF
(150 mL) were added N-hydroxysuccinimide (19.6 g,
170 mmol) and 1,3-dicyclohexylcarbodiimide (35.1 g,
170 mmol) at 0 °C. After stirring at 0 °C for 5 h, the result-
ing insoluble substance was removed by filtration. To the
stirred filtrate were added sodium borohydride (5.60 g,
148 mmol) at 0 °C and then water (50 mL) in 30 min.
After being stirred at 0 °C for 3 h, the reaction mixture
was quenched with 2 N HCl and extracted with EtOAc.
The organic layer was washed with saturated NaHCO3,
brine, and dried over MgSO4. Removal of the volatiles
in vacuo provided an oily solid, which was washed with
toluene–EtOAc, 3:1, to give 39.3 g (71%) of 78a as a white
powder: TLC Rf = 0.36 (toluene–EtOAc, 1:1); 1H NMR
(200 MHz, CDCl3) d 7.81–7.74 (m, 2H), 7.55–7.48 (m,
2H), 6.91 (d, J = 7.0 Hz, 1H), 4.21–4.05 (m, 1H), 3.75–
3.70 (m, 2H), 3.65 (s, 3H), 2.88 (t, J = 5.0 Hz, 1H), 2.53–
2.45 (m, 2H), 2.04–1.94 (m, 2H).
4.78. (4S)-5-Hydroxy-4-{[4-(3-methoxy-1-propynyl)ben-
zoyl]amino}pentanoic acid (80a)
The title compound was obtained as a pale yellow pow-
der in 77% yield from 79a according to the same proce-
dures as described for the preparation of 29: MS
(MALDI, pos.) m/z 344 (M+K)+, 328 (M+Na)+, 306
4.75. Methyl (4R)-5-hydroxy-4-[(4-iodobenzoyl)ami-
no]pentanoate (78b)
1
The title compound was obtained as a white powder in
81% yield from 77b according to the same procedures
(M+H)+; H NMR (200 MHz, DMSO-d6) d 12.00 (s,
1H), 8.12 (d, J = 8.4 Hz, 1H), 7.87 (d, J = 8.3 Hz, 2H),

S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
5421
7.54 (d, J = 8.3 Hz, 2H), 4.73 (t, J = 5.5 Hz, 1H), 4.35 (s,
2H), 4.04–3.87 (m, 1H), 3.55–3.33 (m, 5H), 2.25 (t,
J = 7.3 Hz, 2H), 1.99–1.58 (m, 2H).
4.83. Methyl (4R)-5-(Methoxymethoxy)-4-{[4-(3-meth-
oxy-1-propynyl)benzoyl]amino}pentanoate (81b)
The title compound was obtained quantitatively from 79b
as an off-white powder according to the same procedures
as described for the preparation of 68a: TLC Rf = 0.57
4.79. (4R)-5-Hydroxy-4-{[4-(3-methoxy-1-propynyl)ben-
zoyl]amino}pentanoic acid (80b)
1
(toluene–EtOAc, 1:1); H NMR (200 MHz, CDCl3) d
The title compound was obtained as an off-white pow-
der in 99% yield from 79b according to the same proce-
dures as described for the preparation of 29: TLC
Rf = 0.59 (CHCl3–MeOH–AcOH–H2O, 85:15:1:1); 1H
NMR (200 MHz, DMSO-d6) d 11.98 (br s, 1H), 8.12
(d, J = 8.4 Hz, 1H), 7.85 (d, J = 8.2 Hz, 2H), 7.53 (d,
J = 8.2 Hz, 2H), 4.34 (s, 2H), 4.05–3.83 (m, 1H), 3.50–
3.20 (m, 2H), 3.28 (s, 2H), 2.23–2.19 (m, 2H), 1.89–
1.50 (m, 2H).
7.74 (d, J = 8.4 Hz, 2H), 7.52 (d, J = 8.4 Hz, 2H), 6.70
(d, J = 8.8 Hz, 1H), 4.64 (s, 2H), 4.33 (s, 2H), 4.40–4.25
(m, 1H), 3.75 (dd, J = 10.4, 3.4 Hz, 1H), 3.61 (dd,
J = 10.4, 3.4 Hz, 1H), 3.62 (s, 3H), 3.46 (s, 3H), 3.37 (s,
3H), 2.58–2.38 (m, 2H), 2.12–1.93 (m, 2H).
4.84. (4S)-5-(Methoxymethoxy)-4-{[4-(3-methoxy-1-
propynyl)benzoyl]amino}pentanoic acid (82a)
The title compound was obtained as an off-white powder
in 77% yield from 81a according to the same procedures as
described for the preparation of 29: MS (MALDI, pos.)
4.80. N-[(1S)-4-(Hydroxyamino)-1-(hydroxymethyl)-4-
oxobutyl]-4-(3-methoxy- 1-propynyl)benzamide (18)
1
m/z 372 (M+Na)+, 350 (M+H)+; H NMR (200 MHz,
The title compound was obtained as a pale yellow pow-
der in 30% yield from 80a according to the same proce-
dures as described for the preparation of 2: TLC
Rf = 0.36 (CHCl3–MeOH, 4:1); MS (APCI, pos. 20 V)
m/z 321 (M+H)+; IR (KBr) 1635, 1547, 1502, 1451,
DMSO-d6) d 8.28 (d, J = 8.8 Hz, 1H), 7.86 (d,
J = 8.5 Hz, 2H), 7.55 (d, J = 8.5 Hz, 2H), 4.57 (s, 2H),
4.35 (s, 2H), 4.22–4.04 (m, 1H), 3.55–3.45 (m, 2H), 3.35
(s, 3H), 3.24 (s, 3H), 2.27 (t, J = 7.5 Hz, 2H), 1.97–1.64
(m, 2H).
1314, 1280, 1187, 1095, 1047 cmꢀ1
;
1H NMR
(200MHz, DMSO-d6) d 10.35 (s, 1H), 10.18 (s, 1H),
8.18 (d, J = 8.4 Hz, 1H), 7.88 (d, J = 8.4 Hz, 2H), 7.55
(d, J = 8.4 Hz, 2H), 4.53 (s, 2H), 4.02–3.84 (m, 1H),
4.85. (4R)-5-(Methoxymethoxy)-4-{[4-(3-methoxy-1-
propynyl)benzoyl]amino}pentanoic acid (82b)
3.73–3.34 (m, 2H), 3.35 (s, 3H), 2.07–1.59 (m, 4H); opti-
cal rotation ½aꢁ ꢀ29.4 (c 0.31, DMF); HRMS (FAB)
The title compound was obtained as an off-white powder
in 98% yield from 81b according to the same procedures as
described for the preparation of 29: TLC Rf = 0.47
(CHCl3–MeOH–AcOH–H2O, 100:10:1:1); 1H NMR
(200 MHz, DMSO-d6) d 8.28 (d, J = 8.8 Hz, 1H), 7.86
(d, J = 8.5 Hz, 2H), 7.55 (d, J = 8.5 Hz, 2H), 4.57 (s,
2H), 4.35 (s, 2H), 4.22–4.04 (m, 1H), 3.55–3.45 (m, 2H),
3.35 (s, 3H), 3.24 (s, 3H), 2.27 (t, J = 7.5 Hz, 2H), 1.97–
1.64 (m, 2H).
30
D
calcd for C16H21N2O5: 321.1450. Found: 321.1446.
4.81. N-[(1R)-4-(Hydroxyamino)-1-(hydroxymethyl)-4-
oxobutyl]-4-(3-methoxy-1-propynyl)benzamide (19)
The title compound was obtained as an ivory powder
in 13% yield from 80b according to the same proce-
dures as described for the preparation of 2: TLC
Rf = 0.28 (CHCl3–MeOH–AcOH–H2O, 85:15:1:1); MS
(MALDI, pos.) m/z 343 (M+Na)+, 321 (M+H)+; IR
(KBr) 1630, 1548, 1503, 1446, 1352, 1186, 1102, 1048,
4.86. N-{(1S)-4-(hydroxyamino)-1-[(methoxymeth-
oxy)methyl]-4-oxobutyl}-4-(3-methoxy-1-propynyl)-
benzamide (20)
972 cmꢀ1 1H NMR (200 MHz, CD3OD) d 7.83 (d,
;
J = 8.4 Hz, 2H), 7.51 (d, J = 8.4 Hz, 2H), 4.34 (s,
2H), 4.03–4.15 (m, 1H), 3.62 (d, J = 5.6 Hz, 2H), 3.43
The title compound was obtained as a yellow oil in 94%
yield from 82a according to the same procedures as de-
scribed for the preparation of 2: TLC Rf = 0.22 (CHCl3–
MeOH, 9:1); MS (MALDI, pos.) m/z 387 (M+Na)+, 365
(M+H)+; IR (neat) 1643, 1544, 1501, 1452, 1357, 1150,
(s, 3H), 2.19 (t, J = 7.4 Hz, 2H), 1.77–2.10 (m, 2H);
30
D
optical rotation ½aꢁ +15.2 (c 0.11, DMF); HRMS
(FAB) calcd for C16H21N2O5: 321.1450. Found:
321.1452.
1101, 1040 cmꢀ1 1H NMR (200 MHz, DMSO-d6):d
;
10.35 (s, 1H), 8.32 (d, J = 8.6 Hz, 1H), 7.87 (d,
J = 8.4 Hz, 2H), 7.55 (d, J = 8.4 Hz, 2H), 4.57 (s, 2H),
4.36 (s, 2H), 4.20–4.01 (m, 1H), 3.55–3.44 (m, 2H),
4.82. Methyl (4S)-5-(methoxymethoxy)-4-{[4-(3-meth-
oxy-1-propynyl)benzoyl]amino}pentanoate (81a)
3.35 (s, 3H), 3.24 (s, 3H), 2.09–1.64 (m, 4H); optical
30
D
for C18H25N2O6: 365.1713. Found: 365.1704.
The title compound was obtained quantitatively from
79a as a pale yellow solid according to the same proce-
dures as described for the preparation of 68a: TLC
Rf = 0.74 (CHCl3–MeOH, 9:1); MS (MALDI, pos.)
m/z 402 (M+K)+, 386 (M+Na)+, 364 (M+H)+; 1H
NMR (200 MHz, CDCl3) d 7.75 (d, J = 8.4 Hz, 2H),
7.51 (d, J = 8.4 Hz, 2H), 6.72 (d, J = 8.8 Hz, 1H),
4.65 (s, 2H), 4.41–4.25 (m, 3H), 3.79–3.58 (m, 5H),
3.46 (s, 3H), 3.38 (s, 3H), 2.60–2.35 (m, 2H), 2.15–
1.94 (m, 2H).
rotation ½aꢁ ꢀ25.6 (c 0.25, DMF); HRMS (FAB) calcd
4.87. N-{(1R)-4-(Hydroxyamino)-1-[(methoxymeth-
oxy)methyl]-4-oxobutyl}-4-(3-methoxy-1-propynyl)benz-
amide (21)
The title compound was obtained as a yellow gum in
72% yield from 82b according to the same procedures
as described for the preparation of 2: TLC Rf = 0.25

5422
S. Nakatani et al. / Bioorg. Med. Chem. 14 (2006) 5402–5422
(CHCl3–MeOH–AcOH–H2O, 100:10:1:1); MS (MAL-
DI, pos.) m/z 387 (M + Na)+, 365 (M+H)+; IR (KBr)
1640, 1542, 1500, 1451, 1356, 1213, 1186, 1150, 1100,
References and notes
1. (a) Supuran, C. T.; Scozzafava, A. In Proteinase and
Peptidase Inhibition: Recent Potential Targets for Drug
Development; Smith, H. J., Simons, C., Eds.; Taylor &
Francis: London, New York, 2002; pp 35–61; (b)
Woessner, J. F.; Nagase, H. In Matrix Metalloprotein-
ases and TIMPs; Oxford University Press, 2000; pp 1–
223.
2. Spurlino, J. C.; Smallwood, A. M.; Carlton, D. D.;
Banks, T. M.; Vavra, K. J.; Johnson, J. S.; Cook, E.
R.; Falvo, J.; Wahl, R. C.; Pulvino, T. A.; Wendoloski,
J. J.; Smith, D. L. Proteins: Struct. Funct. Genet. 1994,
19, 98–109.
3. (a) Matsumura, S.; Oue, N.; Kitadai, Y.; Chayama, K.;
Yoshida, K.; Yamaguchi, Y.; Toge, T.; Imai, K.; Nakachi,
K.; Yasui, W. J. Cancer Res. Clin. Oncol. 2004, 130, 259–
265; (b) Nordskog, B. K.; Blixt, A. D.; Zieske, A. W.;
Hellmann, G. M. Cardiovasc. Toxicol. 2004, 4, 75–83; (c)
Pardo, A.; Selman, M. Int. J. Biochem. Cell Biol. 2005, 37,
283–288.
4. (a) Bernardo, M. M.; Brown, S.; Li, Z. H.; Fridman, R.;
Mobashery, S. J. Biol. Chem. 2002, 277, 11201–11207; (b)
Kruger, A.; Arlt, M. J.; Gerg, M.; Kopitz, C.; Bernardo,
M. M.; Chang, M.; Mobashery, S.; Fridman, R. Cancer
Res. 2005, 65, 3523–3526.
1
1038, 965 cmꢀ1; H NMR (200 MHz, CD3OD) d 8.32
(d, J = 8.8 Hz, 1H), 7.82 (d, J = 8.8 Hz, 2H), 7.52 (d,
J = 8.8 Hz, 2H), 4.62 (s, 2H), 4.34 (s, 2H), 4.16–4.31
(m, 1H), 3.62 (d, J = 5.6 Hz, 2H), 3.43 (3H, s), 3.33
(3H, s), 2.20 (t, J = 7.0 Hz, 2H), 1.17–2.11 (m, 2H); opti-
30
D
calcd for C18H25N2O6: 365.1713. Found: 365.1722.
cal rotation ½aꢁ +5.60 (c 0.23, MeOH); HRMS (FAB)
5. Biology. Enzyme assays: MMP-1, MMP-2, MMP-9,
and MMP-3 assays using synthetic substrate
5.1. MMP-1 assay
Commercially available assay kits (Yagai, Yamagata
City, Japan) were used. The solutions provided in the kits
were used unless otherwise stated. A 98 lL portion of en-
zyme solution (0.5 U/mL) and 2 lL of inhibitor solution
(DMSO) were incubated with 100 lL of 0.5 mg/mL
FITC-labeled type I collagen solution at 37 °C for 3 h.
After incubation with 300 L of quenching solution on
ice for 30 min, the reaction mixture was centrifuged at
2000g for 15 min. Supernatant was used for measurement
of fluorescence by RF5300-PC. Excitation and emission
wavelengths were 495 and 520 nm, respectively.
5. Krippl, P.; Langsenlehner, U.; Renner, W.; Yazdani-
Biuki, B.; Koppel, H.; Leithner, A.; Wascher, T. C.;
Paulweber, B.; Samonigg, H. Clin. Cancer Res. 2004, 10,
3518–3520.
6. (a) Whittaker, M.; Floyd, C. D.; Brown, P.; Gearing, A. J.
H. Chem. Rev. 1999, 99, 2735–2776; (b) Supuran, C. T.;
Casini, A.; Scozzafava, A. Med. Res. Rev. 2003, 23, 535–
558.
7. Takahashi, K.; Ikura, M.; Habashita, H.; Nishizaki, M.;
Sugiura, T.; Yamamoto, S.; Nakatani, S.; Ogawa, K.;
Ohno, H.; Nakai, H.; Toda, M. Bioorg. Med. Chem. 2005,
13, 4527–4543.
5.2. MMP-2 and MMP-9 assays11
A mixture of 130 lL of MOCAc-Pro-Leu-Gly-Leu-
Dpa-Ala-Arg-NH2 (final concentration: 15 lM) and
20 lL of inhibitor solution were incubated at 37 °C for
5 min. Enzyme solution (50 lL) was added and the reac-
tion was performed at 37 °C for 10 min. Its fluorescence
was measured by fmax. Excitation and emission wave-
lengths were 320 and 390 nm, respectively.
8. Saito, S.; Hasegawa, T.; Inaba, M.; Moriwake, T.;
Nishida, R.; Fujii, T.; Nomizu, S.; Moriwake, T. Chem.
Lett. 1984, 1389–1392.
9. MMP-1 and MMP-2 were purified from the culture
medium of human dermal fibroblasts stimulated with
phorbol-myristate-acetate and IL-1b. MMP-9 was pur-
chased from Yagai (Yamagata City, Japan).
10. Ikura, M.; Nakatani, S.; Yamamoto, S.; Habashita, H.;
Sugiura, T.; Takahashi, K.; Ogawa, K.; Ohno, H.; Nakai,
H.; Toda, M. Bioorg. Med. Chem., in press.
11. Knight, C. G.; Willenbrock, F.; Murphy, G. A. FEBS
Lett. 1992, 296, 263–266.
12. Nagase, H.; Fields, C. G.; Fields, G. B. J. Biol. Chem.
1994, 269, 20952–20957.
5.3. MMP-3 assay12
A mixture of 190 lL of MOCAc-Arg-Pro-Lys-Pro-Val-
Glu-Nva-Trp-Arg-Lys(Dnp)-NH2 (final concentration:
15 lM) and 10 lL of inhibitor solution were incubated
at 37 °C for 5 min. Enzyme solution (50 lL) was added
and the reaction was performed at 37 °C for 10 min. Its
fluorescence was measured by fmax. Excitation and emis-
sion wavelengths were 320 and 390 nm, respectively.