Convenient preparation and use of a new analytical construct for the analysis and development of solid-phase chemistries

Article abstract of DOI:10.1021/jo034340p

An expedient and scalable synthesis of a versatile new analytical construct intermediate 1 is described. The utility of the intermediate 1 is exemplified by the preparation of the construct resin 14 incorporating an acid-labile linker which is used to con

Full text of DOI:10.1021/jo034340p

Con ven ien t P r ep a r a tion a n d Use of a New An a lytica l Con str u ct
for th e An a lysis a n d Develop m en t of Solid -P h a se Ch em istr ies
Stephen P. Andrews and Mark Ladlow*
GlaxoSmithKline Cambridge Technology Center, University Chemical Laboratory, Lensfield Road,
Cambridge CB2 1EW, U.K.
mark.2.ladlow@gsk.com
Received March 14, 2003
An expedient and scalable synthesis of a versatile new analytical construct intermediate 1 is
described. The utility of the intermediate 1 is exemplified by the preparation of the construct resin
14 incorporating an acid-labile linker which is used to conveniently develop optimized conditions
leading to the preparation of a small compound array 24{1-3,1-3}. The optimized conditions are
shown to work equally well on both the construct resin 14 and the corresponding base resin 15.
In tr od u ction
The solid-phase combinatorial synthesis of chemical
compound libraries, coupled with the ability to efficiently
screen large numbers of compounds utilizing high-
throughput screening (HTS) techniques, has evolved into
a powerful strategy for the identification of pharmaco-
logically active lead molecules within the pharmaceutical
industry.1-3 However, although significant advances have
been made in recent years,4 the development and analysis
of solid-phase chemistries may still prove to be difficult
or unacceptably time-consuming, particularly for large
numbers of compounds.
F IGURE 1. Generic analytical construct.
The analytical enhancer is attached to linker 1 (L1) in
such a way that resin cleavage (“analytical cleavage”)
releases a fragment that is tagged with an amine and is
thus sensitized to ESI+ mass spectrometric analysis.
Alternatively, orthogonal cleavage (“conventional cleav-
age”) at linker 2 (L2) releases only the desired substrate
into solution. However, analytical constructs are not
currently commercially available, and therefore, to fa-
cilitate their widespread adoption for the analysis and
development of solid-phase chemistries, there is a need
to establish convenient syntheses of generic construct
components.8
Herein, we describe the efficient preparation of a new
construct fragment 1 that may be used to assemble
analytical constructs of the type shown in Figure 2. This
analytical construct is particularly useful for the develop-
ment and analysis of solid-phase chemistries employing
widely used acid-labile linkers such as Rink,9 Sasrin,10
and BAL.11 The new construct fragment 1 has been
developed to be amenable to large scale synthesis without
the need for extensive chromatography. In addition,
removal of the N-BOC group reveals a primary amine
(rather than the more hindered secondary amine present
in previous constructs12) which facilitates the attachment
Recently, to help overcome this problem, the concept
of “analytical constructs” has been introduced.5 An
analytical construct is a modified solid-phase dual linker6
which is assembled from two orthogonal linkers con-
nected through the intermediacy of an analytical enhanc-
ing group (Figure 1). The “analytical enhancer” is a small
molecule which contains a “peak splitter” (mixture of
isotopes) in order to produce readily identifiable ions with
a characteristic splitting pattern in the mass spectrom-
eter and a UV chromophore which absorbs at a remote
wavelength to facilitate direct quantification.7
(1) Golebiowski, A.; Klopfenstein, S. R.; Portlock, D. E. Curr. Opin.
Chem. Biol. 2001, 5, 273.
(2) Yoshida, J .; Itami, K. Chem. Rev. 2002, 102, 3693-3716.
Ganesan, A. Drug Discovery Today 2002, 7 (1), 47.
(3) Do¨rwald, F. Z. Organic Synthesis on Solid Phase; Wiley-VCH:
Weinheim, 2000. Bannwarth, W.; Felder, E. Combinatorial Chemistry.
A Practical Approach; Wiley-VCH: Weinheim, 2000.
(4) de Miguel, Y. R., Ed. Special Section on Analytical Methods for
the Combinatorial Sciences. Biotechnol. Bioeng. 2001, 71 (2), 62 pp.
(5) Congreve, M. S.; Ley, S. V.; Scicinski, J . J . Chem. Eur. J . 2002,
8, 1768. McKeown, S. C.; Watson, S. P.; Carr, R. A. E.; Marshall, P.
Tetrahedron Lett. 1999, 40, 2407. Murray, P. J .; Kay, C.; Scicinski, J .
J .; McKeown, S. C.; Watson, S. P.; Carr, R. A. E. Tetrahedron Lett.
1999, 40, 5609. Berst, F.; Holmes, A. B.; Ladlow, M.; Murray, P. J .
Tetrahedron Lett. 2000, 41, 6649.
(6) For a general review of solid-phase linkers, see: Guillieri, F.;
Orain, D.; Bradley, M. Chem Rev. 2000, 100 (6), 2091.
(7) Williams, G. M.; Carr, R. A. E.; Congreve, M. S.; Kay, C.;
McKeown, S. C.; Murray, P. J .; Scicinski, J . J .; Watson, S. P. Angew.
Chem., Int. Ed. 2000, 39, 3293.
(8) Lorthioir, O.; McKeown, S. C.; Parr, N. J .; Washington, M.;
Watson, S. P. Tetrahedron Lett. 2000, 41, 8609.
(9) Rink, H. Tetrahedron Lett. 1987, 28, 3787.
(10) Mergler, M.; Tanner, R.; Gosteli, J .; Grogg, P. Tetrahedron Lett.
1988, 29, 4005.
(11) Albericio, F.; Barany, G. Int. J . Pept. Prot. Res. 1987, 30, 206.
10.1021/jo034340p CCC: $25.00 © 2003 American Chemical Society
Published on Web 06/11/2003
J . Org. Chem. 2003, 68, 5525-5533
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Andrews and Ladlow
SCHEME 1 a
F IGURE 2.
of L2 and, importantly, the incorporation of the deute-
rium mass tag is now performed more cost-effectively
using D2O. Further, the synthesis of the anthryl contain-
ing component in 1 may be readily modified to introduce
different isotopic splitting patterns by using the ap-
propriate combination of deuterated reducing agents
sodium borohydride and lithium aluminum hydride in
its preparation. The incorporation of the mass spectro-
scopic “peak splitter” is a versatile and useful feature
inherent within the analytical construct approach. This
facilitates the identification of construct derived frag-
ments in the mass spectrum which may be performed
automatically, without the precise knowledge of molec-
ular weights, using commercial MS software to search
the spectrum for peaks with the desired peak splitting.
Although not reported herein, the ability to readily
prepare constructs with different peak splittings also
presents the opportunity to implement mass encoding of
pooled resin beads.13
a
c
Reagents and conditions: (i) H2SO4, MeOH, reflux, 94%; (ii)
BnSH, DIPEA, MeOH, 0 °C to rt, 90%; (iii) Cl2(g), AcOH-H2O,
rt, 76%; (iv) Meldrum’s acid, py, rt, 95%; (v) NaBH4, MeOH, 0 °C
to rt, 97%; (vi) D2O or H2O, py, reflux, 7a 99%, 7b 94%; (vii)
LiAlH4, THF, rt, 8a 94%, 8b 97%; (viii) MsCl, DIPEA, CH2Cl2, 0
°C; (ix) NaI, Me2CO, reflux, 9a 85%, 9b 94%.
SCHEME 2 a
a
Reagents and conditions: (i) NaBD4, MeOH, 0 °C to rt, 72%;
(ii) D2O, py, reflux, quant.
the corresponding alkane 6a . Both compounds were
isolated in high purity and excellent yields by simple
filtration. The required D2 isotopic mass splitter was
conveniently introduced upon hydrolysis/decarboxylation
of 6a in the presence of D2O to afford 7a .15 Similarly, the
H2 analogue 7b was obtained by hydrolysis/decarboxy-
lation of 6a in the presence of H2O. The carboxylic acids
7a and 7b were reduced with lithium aluminum hydride
to afford the alcohols 8a and 8b, which were then
converted into the corresponding iodides 9a and 9b,
respectively, following conversion to the intermediate
methanesulfonate and subsequent displacement with
sodium iodide in acetone.
This synthesis is both convenient and versatile and
provides ready access to a range of alternative fragments
incorporating different isotopic splitting patterns. For
example, although not used in this study, the preparation
of the corresponding D3 acid 7c (Scheme 2) was achieved
following reduction of the Meldrum’s acid adduct 5 with
sodium borodeuteride to afford the D1 alkane 6b. This
Resu lts a n d Discu ssion
An acid-stable sulfonamide was chosen as linker L1
in order to establish the desired orthogonality to the acid-
labile linker L2. The required sulfonyl chloride 3 was
readily obtained in 64% overall yield starting from
4-chloro-3-nitrobenzoic acid 2 by modification of the
reported procedure (Scheme 1).14
The anthracene fragment incorporating the isotopic
mass splitter required for the analytical enhancer was
prepared by condensation of Meldrum’s acid with 9-an-
thraldehyde 4 to give the alkylidene 5. Conjugate reduc-
tion of 5 in the presence of sodium borohydride afforded
(12) Congreve, M. S.; Ladlow, M.; Marshall, P.; Parr, N.; Scicinski,
J . J .; Sheppard, T.; Vickerstaffe, E.; Carr, R. A. E. Org. Lett. 2001, 3,
507.
(13) Geysen, H. M.; Wagner, C. D.; Bodnar, W. M.; Markworth, C.
J .; Parke, G. J .; Schoenen, F. J .; Wagner, D. S.; Kinder, D. S. Chem.
Biol. 1996, 3 (8), 679.
(14) Pattarawarapan, M.; Chen, J .; Steffensen, M.; Burgess, K. J .
Comb. Chem. 2001, 3, 102.
(15) Kadam, A. J .; Desai, U. V.; Mane, R. B. J . Labelled Cpd.
Radiopharm. 1999, 42, 835.
5526 J . Org. Chem., Vol. 68, No. 14, 2003

Analysis and Development of Solid-Phase Chemistries
SCHEME 3 a
SCHEME 4 a
a
Reagents and conditions: (i) R1NH2 16{1-3}, AcOH, TMOF/
NMP; (ii) Me4NBH(OAc)3, AcOH, CH2Cl2; (iii) 4-iodobenzoyl
chloride, DIPEA, CH2Cl2; (iv) R2B(OH)2 21{1-3}, K3PO4, Pd-
(PPh3)4, DMF/H2O, 80 °C; (v) 90:5:5 TFA/TES/H2O.
a
Reagents and conditions: (i) BOCHN(CH2)3NH2, DIPEA,
array using the commonly employed solid-phase reactions
of reductive amination, acylation, and Suzuki coupling
(Scheme 4).
CH2Cl2, 92%; (ii) (1:1) 9a /9b, PS-BEMP, DMF, 89%; (iii) NaOH-
H2O, THF, 100%; (iv) ArgoGel-NH2, DIC, HOBt, DIPEA, DMF;
(v) (1:1) TFA-CH2Cl2, PhOH, H2O; (vi) 4-[(4-formyl-3-methox-
y)phenoxy]butyric acid, PyBOP, HOBt, DIPEA, DMF, rt.
For each step, a number of trial reactions were
performed on small quantities of construct resin. A
sample of beads (10-20) was removed in each case and
subjected to analytical cleavage (HS(CH2)2OH/NaOMe/
MeOH) followed by analysis of the cleavage solution by
LC-MS. Based upon the interpretation of these results,
reaction conditions (solvent, reagents, concentrations,
equivalents) were modified, and the process was repeated
in an iterative manner until optimized conditions were
established.
In practice, for reasons of economy, it is conceivable
that library chemistry would be developed on a construct
derivatized resin but that subsequent library production
would be performed on a non-derivatized base resin.
Therefore, the compound array outlined in Scheme 4 was
prepared in parallel on both the construct resin 14 and
the corresponding base resin 15 derivatized with the acid-
labile linker L2 but lacking the analytical construct
fragment. The results were compared to determine if the
construct was predictive of optimal conditions that were
applicable to both resins. Thus, according to the condi-
tions determined, the resins 14 and 15 were subjected
to a two-step reductive amination procedure whereby the
imine was first formed in the presence of trimethyl
orthoformate (TMOF) and the appropriate amine 16{1-
3}. The resins were washed and the reducing agent
tetramethylammonium triacetoxyborohydride was intro-
was subsequently hydrolyzed and decarboxylated in the
presence of D2O to afford the D3 acid 7c in good overall
yield. The acid may be converted into the corresponding
alcohol or alkyl halide as required in an analogous
manner to that outlined in Scheme 1.
Addition of the sulfonyl chloride 3 to mono N-BOC-
1,3-diaminopropane gave the intermediate sulfonamide
10, which was alkylated with a 1:1 mixture of the iodides
9a and 9b in the presence of BEMP on polystyrene16 to
give the mixed sulfonamide 11 (Scheme 3). The sulfon-
amide 11 was saponified to the versatile core analytical
fragment 1 which was attached to ArgoGel amino resin
to give the N-BOC resin 12.
To demonstrate the utility of the analytical construct
resin 12, the N-BOC protecting group was removed with
a solution of TFA in dichloromethane (1:1) to afford 13,
and the acid-labile linker L2, 4-[(4-formyl-3-methoxy)-
phenoxy]butyric acid17 was attached to provide the
construct resin 14. The resin 14 was used to optimize
the conditions required to prepare a small compound
(16) BEMP (2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-
1,3,2-diazaphosphorine) on polystyrene; commercially available from
Sigma-Aldrich. Cf: Schwesinger, R. Chimia 1985, 39, 269.
(17) Ngu, K.; Patel, D. V. J . Org. Chem. 1997, 62, 7088.
J . Org. Chem, Vol. 68, No. 14, 2003 5527

Andrews and Ladlow
TABLE 1. Com p a r ison of P r od u ct Yield s fr om
Con str u ct Der iva tized a n d Non d er iva tized Resin s 22 a n d
23
base resin
construct resin
% HPLC
% HPLC
compd 24{x,y}
puritya
% yieldb
puritya
% yieldb
{1,1}
{2,1}
{3,1}
{1,2}
{2,2}
{3,2}
{1,3}
{2,3}
{3,3}
>95
>95
>95
>95
95
>95
>95
>95
>95
78
55
67
74
79
73
81
79
80
>95
>95
>95
>95
>95
>95
91
70
63
66
74
74
79
81
81
82
>95
>95
a
b
Determined at 254 nm. Overall yields were calculated by 1H
NMR integration following cleavage from the resin and removal
of solvents by preparing solutions in DMSO-d6 previously cali-
brated with p-nitrophenol.
duced to afford the amino resins 17{1-3} and 18{1-3}
respectively. Acylation with 4-iodobenzoyl chloride/DI-
PEA in dichloromethane then gave the iodo-resins 19{1-
3} and 20{1-3}. Treatment of the resins 19{1-3} and
20{1-3} with the boronic acids 21{1-3} in the presence
of Pd(PPh3)4/K3PO4 at 80 °C for 1 h in 15% v/v aqueous
DMF gave the resin-bound biaryls 22{1-3,1-3} and
23{1-3,1-3}.
The resins 22{1-3,1-3}and 23{1-3,1-3} were cleaved
upon exposure to TFA/triethylsilane/H2O (90:5:5; 2 × 1
h) to afford the carboxamides 24{1-3,1-3}. The purities
of the compounds obtained from both the construct and
base resins were found to be excellent (Table 1). In
addition, the yields of material from both resins were
found to correlate well, within the limits of experimental
deviation.
To illustrate the utility of analytical construct analysis
in both reaction development and quality control analy-
sis, some representative construct cleavage data obtained
during early solid-phase studies is given in Figures 3-5.
An important prerequisite for successful solid-phase
synthesis is to ensure that the initial resin loading step
is both reliable and efficient. Failure in this respect leads
at best to a reduced final cleavage yield and more
typically to contaminated cleavage products that require
further purification. When loading an acid-labile alde-
hyde linker such as that present on the resin 15 by
reductive amination, the ability to adequately monitor
this process can be problematic. For example, the direct
acid-mediated cleavage of a sample of the product
secondary amino-resin in the presence of a solution of
95% (v/v) TFA in dichloromethane typically fails.18 An
alternative is to monitor the resin beads by IR or MAS-
1H NMR and observe the disappearance of the aldehydic
resonance. However, a competing reaction is the direct
reduction of the aldehyde linker to the corresponding
alcohol and this can be more difficult to observe by IR/
NMR. In contrast, the use of the analytical construct
resin 14 is particularly useful since direct cleavage of the
BAL fragment in both the starting aldehyde and product
resins can be readily achieved by an orthogonal, non-acid-
mediated (thiolate) cleavage process. The analytical
fragment obtained is then readily amenable to LC-MS
F IGURE 3. Analytical cleavage data obtained during opti-
mization of the reductive amination of resin 14.
analysis enabling the outcome of the reductive amination
loading step to be determined with confidence.
This is illustrated in Figure 3 where we determined
that the use of a two-stage reductive amination processs
imine formation in the presence of TMOF followed by
thorough washing of the resin and then introduction of
the reducing agent tetramethylammonium triacetoxyboro-
hydridesleads to the desired resin 17{1} as evidenced
by the isolation of the cleavage fragment 25a . However,
we were surprised to find that the use of the more
powerful reducing agent tetrabutylammonium borohy-
dride under identical conditions led to not only the
desired resin-bound secondary amine but also approxi-
mately 40% of the corresponding N-methyl resin 26 (as
evidenced by fragment 25b). A similar result (not shown)
was obtained when sodium borohydride was used as the
reducing agent (approximately 20% 26). The N-methyl-
substituted resin 26 would remain unmodified in the
subsequent synthetic transformations and lead to a
reduced overall yield. However, it is unlikely that the
reason for this would have been apparent without the
use of the analytical construct. We examined the conse-
(18) Fivush, A. M.; Willson, T. M. Tetrahedron Lett. 1997, 38, 7151.
5528 J . Org. Chem., Vol. 68, No. 14, 2003

Analysis and Development of Solid-Phase Chemistries
TABLE 2. An a lytica l Clea va ge Da ta Lea d in g to th e
P r ep a r a tion of a Typ ica l Ar r a y Mem ber 24{1,1}
F IGURE 4. Analytical cleavage data obtained during acyla-
tion of resin 17.
F IGURE 5. Analytical cleavage data obtained during opti-
mization of the Suzuki coupling of resin 19.
quences of changing the reductive amination conditions
(alternative solvents, presence or absence of acetic acid
as a catalyst) in an attempt to understand the origin of
the N-methylation that was observed. These studies were
not conclusive, but suggested that N-formylation (or
formation of the corresponding dimethyl acetal) may
occur in the presence of TMOF and that this intermediate
is subsequently reduced in the presence of a “strong”
reducing agent such as sodium borohydride, but under-
goes hydrolysis in the presence of tetramethylammonium
triacetoxyborohydride to afford the desired secondary
amino-resin. In any event, these difficulties were circum-
vented by the use of tetramethylammonium borohydride
as the reducing agent (see Table 2, entry 2).
a
Analytical cleavage fragments obtained by treatment of the
parent construct resins with HSCH2CH2OH/NaOMe/MeOH at
room temperature for 10 min. The resulting solutions were
analyzed by LC-MS at 386 nm.
when the analytical cleavage data was obtained that the
fragments 25a and 25c corresponding to the resin-bound
starting amine and the desired acylated product, respec-
tively, were shown to be the only compounds present on
the resin in a ratio of 52:48 (Figure 4). As expected.
increasing the number of equivalents of 4-iodobenzoyl
chloride resulted in complete conversion to the desired
acylated resin 19{1} (see Table 2, entry 3).
A more straightforward outcome was encountered in
the following acylation step. In an early experiment, the
acylation of resin 17{1} did not go to completion. While
a simple Kaiser test19 on the resulting resin indicated
that free amino groups were still present, it was only
(19) Kaiser, E.; Colescott, R. L.; Bossinger, C. D.; Cook, P. I. Anal.
Biochem. 1970, 200, 803.
J . Org. Chem, Vol. 68, No. 14, 2003 5529

Andrews and Ladlow
was stirred at room temperature for 64 h and cooled to 0 °C,
and the yellow precipitate obtained was collected by filtration.
The solid was washed successively with cold methanol (50 mL),
ethanol/water mixture (2:8, 2 × 50 mL), and hexane (50 mL)
and dried in vacuo to yield the title compound as a yellow
powder (25.5 g, 90%). Mp: 138-139 °C. IR: νmax (cm-1) 1710,
1669, 1606, 1520 and 1497. 1H NMR (CDCl3, 400 MHz): δH
3.9 (3 H, s), 4.2 (2 H, s), 7.35 (3 H, m), 7.4 (2 H, m), 7.5 (1 H,
d, J ) 9 Hz), 8.1(1 H, dd, J ) 9, 2 Hz), 8.8 (1 H, d, J ) 2 Hz).
13C NMR (CDCl3, 100 MHz): δC 38.0, 53.0, 126.9, 127.1, 127.7,
128.4, 129.4, 129.5, 134.0, 134.6, 144.2, 145.5, 165.3. HPLC
(254 nm): tR ) 5.89 min (100%). MS (EI): m/z 303.1 (M+, 33),
272.1 (30), 238.2 (35), 197.1 (100), 164.1 (40), 121.1 (25). HR-
MS (EI): m/z calcd (C15H13NO4S) 303.0567, found 303.0567
M+. Anal. Calcd for C15H13NO4S: C, 59.39; H, 4.32; N, 4.62;
S, 10.57. Found: C, 59.01; H, 4.31; N, 4.57; S, 10.50.
Similarly, in an early attempt, the Suzuki coupling
reaction of resin 19 did not proceed to completion. This
was again clearly evident from the analytical cleavage
data (Figure 5) where, in this case, the analytical
fragments derived from the starting iodide 25c, the
dehalogenated analogue 25d , and the desired biaryl
product 25e were all observed to be present on the resin.
Unfortunately, relative quantification was not possible
in the case of 25c and 25e which were observed to coelute
under a range of HPLC conditions. By increasing the
number of equivalents of boronic acid present, it was
found that this transformation reliably went to comple-
tion to give only the desired resin-bound biaryl adduct
22{1,1} (see Table 2, entry 4).
The analytical cleavage data for the optimized reaction
conditions developed leading to the preparation of a
representative array compound 24{1,1} is shown in Table
2. For each step, the analytical resin cleavage and LC-
MS analysis was conveniently performed in only 20-25
min, and it can readily be seen that, under the optimized
reaction conditions, all the solid-phase transformations
proceeded cleanly.
In conclusion, an expedient and scalable route to a
versatile new analytical construct intermediate 1 is
described. The utility of the intermediate 1 has been
illustrated by the preparation of the analytical construct
resin 14 incorporating the acid-labile linker 4-[(4-formyl-
3-methoxy)phenoxy]butyric acid. The resin 14 has been
used to optimize conditions for the preparation of a
compound array 24{1-3,1-3}. Data obtained using both
the construct resin 14 and the analogous base resin 15
were found to be in good agreement, thereby demonstrat-
ing that this analytical construct may be used to deter-
mine optimized reaction conditions that are also appli-
cable to the corresponding base resin.
Meth yl 4-Ch lor osu lfon yl-3-n itr oben zoa te (3). Chlorine
gas was bubbled through a suspension of methyl 4-benzylsul-
fanyl-3-nitrobenzoate (25.4 g, 83.7 mmol) in acetic acid/water
(2:3, 500 mL) for 1.5 h. The mixture was stirred under the
chlorine atmosphere for 19 h when the system was purged with
nitrogen and the solvent was concentrated in vacuo. The
resulting yellow precipitate was collected by filtration, washed
with hexane (2 × 50 mL), and recrystallized from chloroform/
hexane to afford 3 as white crystals (17.8 g, 76%). Mp: 101-
1
102 °C. IR: νmax (cm-1) 1720, 1683, 1547. H NMR (400 MHz,
CDCl3): δH 4.0 (3 H, s), 8.3 (1 H, d, J ) 8 Hz), 8.45 (1 H, dd,
J ) 8, 2 Hz), 8.5 (1 H, s). 13C NMR (100 MHz, CDCl3): δC
54.0, 126.5, 131.2, 133.8, 138.0, 139.0, 147.7, 163.4. HPLC (254
nm): tR ) 5.05 min, (94%). MS (EI): m/z 279.1 (M+, 15), 244.1
(100), 154.0 (15), 138.0 (30), 119.1 (35). HR-MS (EI): m/z calcd
(C8H6ClNO6S) 278.9604, found 278.9611 M+. Anal. Calcd for
C8H6ClNO6S: C, 34.36; H, 2.16; N, 5.01; S, 11.47; Cl, 12.68.
Found: C, 34.59; H, 2.25; N, 4.45; S, 11.42; Cl, 12.64.
5-An th r a cen -9-ylm eth ylen e-2,2-d im eth yl[1,3]d ioxa n e-
4,6-d ion e (5). A mixture of 9-anthraldehyde (20.0 g, 97.0
mmol) and Meldrum’s acid (14.3 g, 99.0 mmol) in pyridine (80
mL) was stirred at room temperature for 6 h. The resulting
mixture was concentrated in vacuo, and a mixture of ethyl
acetate/hexane (1:4, 50 mL) was added. The solid obtained was
collected by filtration, washed successively with ethyl acetate/
hexane (1:4, 50 mL) and hexane (50 mL), and dried in vacuo
to afford 5 as a white solid (31.7 g, 95%). Mp: 193-194 °C.
IR: νmax (cm-1) 1765, 1731, 1621.1H NMR (400 MHz, CDCl3):
δH 1.9 (6 H, s), 7.5 (4 H, m), 7.8 (2 H, m), 8.1 (2 H, m), 8.5 (1
H, s), 9.5 (1 H, s). 13C NMR (100 MHz, CDCl3): δC 28.5, 105.3,
121.4, 124.9, 125.9, 127.2, 127.5, 129.0, 129.7, 130.7, 131.3,
158.1, 158.3, 162.3. HPLC (386 nm): tR ) 5.72 min (100%).
MS (ESI+): m/z 388.3 (50), 379.2 (15), 372.3 (25), 350.1
(MNH4+, 20), 344.2 (100), 328.2 (45). HR-MS (ESI+): m/z calcd
(C21H20NO4) 350.1392, found 350.1399 (MNH4)+. Anal. Calcd
for C21H16O4: C, 75.89; H, 4.85. Found: C, 75.80; H, 4.87.
Exp er im en ta l Section
Gen er a l Con d ition s for LC-MS An a lysis. Routine LC-
MS analyses were performed on an analytical HPLC equipped
with a Supelcosil ABZ+PLUS column (3.3 cm, 4.6 mm L, 3
µm). Method: eluent, (A) water, 0.1% TFA, (B) acetonitrile
95%, water 5%, TFA 0.05%; gradient, 10-95% B in A (1 mL
min-1) over 8 min; detection, UV (215, 230, 254, 386 nm). The
mass spectrometer was fitted with an electrospray ionization
source, and mass spectra were obtained in both positive- and
negative-ion modes (ESI().
Meth yl 4-Ch lor o-3-n itr oben zoa te. Concentrated sulfuric
acid (10 mL) was cautiously added to a chilled (0 °C) solution
of 4-chloro-3-nitrobenzoic acid (50.0 g, 250 mmol) in methanol
(200 mL) and the resulting mixture heated under reflux for
16 h. The reaction mixture was evaporated to dryness under
reduced pressure, and the solid obtained was recrystallized
from ethyl acetate/hexane mixture and washed successively
with water (2 × 50 mL) and hexane (2 × 50 mL) to afford the
title compound as white crystals (50.1 g, 94%). Mp: 78-79
°C. IR: νmax (cm-1) 1714, 1676, 1604, 1536. 1H NMR (400 MHz,
CDCl3): δH 4.0 (3 H, s), 7.6 (1 H, d, J ) 8 Hz), 8.15 (1 H, dd,
J ) 8, 2 Hz), 8.5 (1 H, s). 13C NMR (100 MHz, CDCl3): δC
53.3, 127.0, 130.5, 132.1, 132.6, 134.0, 148.3, 164.6. HPLC (254
nm): tR ) 4.77 min (97%). MS (EI): m/z 215.1 (M+, 55), 184.1
(100), 154.1 (20), 138.0 (55), 110.0 (30). HR-MS (EI): m/z calcd
(C8H6ClNO4) 214.9985, found 214.9987 M+.
5-An th r a cen -9-ylm eth yl-2,2-d im eth yl[1,3]d ioxa n e-4,6-
d ion e (6a ). Sodium borohydride (1.23 g, 32.0 mmol) was added
gradually to a solution of the alkylidene 5 (9.97 g, 30.0 mmol)
in methanol (200 mL) with external cooling so as to maintain
the temperature below 20 °C. The resulting mixture was
warmed to room temperature and stirred for 1 h before being
recooled to 0 °C. The product was precipitated by dropwise
addition of aqueous HCl (100 mL, 10%) and collected by
filtration. The solid was washed with ice-cold water (3 × 50
mL) and dried in vacuo to afford 6a as an orange powder (9.64
g, 96%). Mp: 168-169 °C. IR: νmax (cm-1) 1772, 1735, 1623,
1524. 1H NMR (400 MHz, CDCl3): δH 1.6 (3 H, s), 1.8 (3 H, s),
3.9 (1 H, t, J ) 7 Hz), 4.5 (2 H, d, J ) 7 Hz), 7.5 (2 H, m), 7.6
(2 H, m), 8.0 (2 H, d, J ) 9 Hz), 8.4 (2 H, s), 8.5 (1 H, d, J )
9 Hz). 13C NMR (100 MHz, CDCl3): δC 24.4, 26.8, 29.2, 49.6,
105.5, 124.8, 125.5, 126.7, 128.0, 129.9, 130.5, 131.0, 132.1,
165.7. HPLC (386 nm): tR ) 5.91 min (100%). MS (ESI+): m/z
388.3 (40), 368.1 (50), 352.2 (MNH4+, 85), 328.2 (30). HR-MS
(ESI+): m/z calcd (C21H22NO4) 352.1549, found 352.1562
Meth yl 4-Ben zylsu lfa n yl-3-n itr oben zoa te. A solution of
benzyl mercaptan (11.4 mL, 97.0 mmol) in methanol (25 mL)
was added at 0 °C to a stirring suspension of the methyl
4-chloro-3-nitrobenzoate (20.0 g, 93 mmol) and DIPEA (19.4
mL, 111 mmol) in methanol (225 mL). The resulting mixture
5530 J . Org. Chem., Vol. 68, No. 14, 2003

Analysis and Development of Solid-Phase Chemistries
(MNH4)+. Anal. Calcd for C21H18O4: C, 75.43; H, 5.43. Found:
C, 75.41; H, 5.44.
H, s). 13C NMR (100 MHz, CDCl3): δC 24.3, 33.8 (m), 62.9,
124.7, 125.2, 125.9, 126.2, 129.6, 130.1, 132.0, 134.7. HPLC
(386 nm): tR ) 5.33 min (100%). MS (ESI+): m/z 239.1 (MH+,
20), 221.1 (100), 191.1 (50). HR-MS (ESI+): m/z calcd
(C17H14D2O) 239.1405; found 239.1406 (MH)+.
3-An th r a cen -9-ylp r op a n -1-ol (8b). The procedure for the
H2 analogue 8a , was repeated using the propionic acid 7b (21.0
g, 84.0 mmol) in place of 7a . The alcohol 8b was obtained as
sand-colored crystals (19.3 g, 97%). Mp: 100-101 °C. IR νmax
(cm-1): 3669, 2926, 1621, 1408, 1039. 1H NMR (400 MHz,
CDCl3): δH 2.10 (2 H, m), 3.73 (2 H, t, J ) 8 Hz), 3.85 (2 H, t,
J ) 6 Hz), 7.5-7.6 (4 H, m), 8.00 (2 H, d, J ) 8 Hz), 8.32 (2 H,
d, J ) 8 Hz), 8.35 (1 H, s). 13C NMR (100 MHz, CDCl3): δC
24.5, 34.4, 63.1, 124.7, 125.2, 125.9, 126.2, 129.6, 130.1, 132.0,
134.7. HPLC (386 nm): tR ) 5.77 min (100%). MS (ESI+): m/z
284.2 (20), 256.2 (80), 254.2 (MNH4+, 55), 235.1 (20). HR-MS
(ESI+): m/z calcd (C17H20NO) 254.1544, found 254.1554
(MNH4)+.
9-(2-d 2-3-Iod op r op yl)a n th r a cen e (9a ). Caution: handle
with care; this compound is an alkylating agent and irritant!
A solution of methanesulfonyl chloride (88.0 mmol, 6.80 mL)
in dichloromethane (30 mL) was added to a stirring mixture
of the alcohol 8a (19.3 g, 81.0 mmol) and DIPEA (20.7 mL,
119 mmol) in dichloromethane (300 mL) at 0 °C. The mixture
was stirred at 0 °C for 0.5 h, then washed successively with
water (150 mL), aqueous HCl solution (100 mL, 10%), and
saturated aqueous sodium bicarbonate solution (100 mL). The
separated organic phase was dried (MgSO4) and evaporated
under reduced pressure to afford the mesylate which was
diluted with acetone (300 mL) and mixed with sodium iodide
(56.2 g, 375 mmol). The mixture was heated under reflux for
0.5 h and then concentrated in vacuo. The residue was
partitioned between water (450 mL) and ethyl acetate (450
mL) and the separated organic phase was washed with brine,
dried (MgSO4), and evaporated under reduced pressure to yield
the iodide 9a as a beige solid (22.3 g, 85%). Mp: 99-100 °C.
IR νmax (cm-1): 3048, 1622, 1446. 1H NMR (400 MHz, CDCl3):
δH 3.37 (2 H, s), 3.72 (2 H, s), 7.46 (2 H, m), 7.51 (2 H, m), 8.00
(2 H, d, J ) 9 Hz), 8.29 (2 H, d, J ) 9 Hz), 8.36 (1 H, s). 13C
NMR (100 MHz, CDCl3): δC 7.0, 29.0, 34.6 (m), 124.5, 125.3,
5-An th r a cen -9-yl-(d )-m eth yl-2,2-d im eth yl[1,3]d ioxa n e-
4,6-d ion e (6b). The procedure for 6a was repeated using
sodium borodeuteride (1.23 g, 30.6 mmol) and the alkylidene
5 (10.1 g, 30.4 mmol) to afford 6b as an orange solid (9.97 g,
1
98%). Mp: 164-165 °C. IR: νmax (cm-1) 1747, 1306. H NMR
(400 MHz, CDCl3): δH 1.6 (3 H, s), 1.8 (3 H, s), 3.9 (1 H, m),
4.5 (2 H, m), 7.5 (2 H, m), 7.6 (2 H, m), 8.0 (2 H, d, J ) 9 Hz),
8.4 (2 H, s), 8.5 (1 H, d, J ) 9 Hz). 13C NMR (100 MHz,
CDCl3): δC 24.0 (m), 26.7, 29.2, 49.5, 105.5, 124.7, 124.7, 126.0,
127.9, 129.8, 130.4, 130.9, 132.0, 165.6. HPLC (386 nm): tR
)
5.97 min (100). MS (ESI+): m/z 388.2 (55), 379.2 (20), 369.2
(35), 353.2 (MNH4+, 60), 344.2 (100), 328.2 (40). HR-MS
(ESI+): m/z calcd (C21H21DNO4) 353.1612, found 353.1615
(MNH4)+.
3-An th r a cen -9-yl-(2-d 2)-p r op ion ic Acid (7a ). Deuterium
oxide (30 mL) was added to a solution of the dione 6a (30.1 g,
90.0 mmol) in pyridine (100 mL) and the mixture refluxed for
16 h. The resulting suspension was concentrated in vacuo and
diluted with aqueous HCl (100 mL, 10%) and ethyl acetate
(300 mL). The mixture was further diluted with water and
the separated aqueous phase extracted with ethyl acetate. The
combined organic layers were washed with brine, dried
(MgSO4), and evaporated under reduced pressure to yield the
acid 7a as a yellow solid (22.4 g, 99%). Mp: 192-193 °C. IR
νmax (cm-1): 3053, 1720, 1690, 1043.1H NMR: δH (400 MHz,
DMSO-d6) 3.82 (2 H, s), 7.5-7.6 (4 H, m), 8.07 (2 H, d, J ) 9
Hz), 8.30 (2H, d, J ) 9 Hz), 12.30 (1 H, s). 13C NMR (100 MHz,
DMSO-d6): δC 23.0, 36.0 (m), 124.4, 125.4, 126.3, 126.4, 129.4,
131.5, 133.3, 174.1. HPLC (386 nm): tR ) 5.82 min, (100%).
MS (ESI+): m/z 270.2 (MNH4+, 30), 256.2 (85), 240.2 (15). HR-
MS (ESI+): m/z calcd (C17H16D2NO2) 270.1463, found 270.1475
(MNH4)+.
3-An th r a cen -9-ylp r op ion ic Acid (7b). The procedure for
7a was repeated using water (30 mL) and the dione 6a (31.6
g, 94.0 mmol) to yield the acid 7b as a yellow solid (22.0 g,
94%). Mp: 194-195 °C. IR νmax (cm-1): 3047, 1721, 1694, 1495.
1H NMR (400 MHz, DMSO-d6): δH 2.62 (2 H, t, J ) 9 Hz),
3.84 (2 H, t, J ) 9 Hz), 7.4-7.6 (4 H m), 8.08 (2 H, d, J ) 8
Hz), 8.32 (2 H, d, J ) 8 Hz), 8.50 (1 H, s), 12.20 (1 H, brs). 13C
NMR (100 MHz, DMSO-d6): δC 23.5, 35.9, 124.8, 125.8, 126.6,
126.2, 126.6, 129.7, 130.1, 132.0, 133.2. HPLC (386 nm): tR
)
7.41 min (100%). MS (ESI+): m/z 433.1 (20), 349.0 (MH+, 100),
221.1 (50), 191.0 (28). HR-MS (ESI+): m/z calcd (C17H13D2I)
349.0422, found 349.0417 (MH)+.
126.8, 129.7, 129.8, 131.8, 133.7, 174.4. HPLC (386 nm): tR
5.83 min, (100%). MS (ESI+): m/z 300.1 (30), 268.1 (MNH4
)
+
,
15), 256.2 (55), 212.1 (100). HR-MS (ESI+): m/z calcd (C17H18
-
9-(3-Iod op r op yl)a n th r a cen e (9b). Caution: handle with
care; this compound is an alkylating agent and irritant! The
procedure for the iodide 9a was repeated using the H2 analogue
8b (18.8 g, 79.0 mmol) in place of 8a . The crude product was
recrystallized from ethyl acetate/hexane to afford the iodide
9b as a beige solid (25.8 g, 94%). Mp: 95-96 °C. IR νmax (cm-1):
1622, 1492. 1H NMR (400 MHz, CDCl3): δH 2.33 (2 H, m), 3.45
(2 H, t, J ) 8 Hz), 3.75 (2 H, t, J ) 8 Hz), 7.4-7.6 (4 H, m),
8.01 (2 H, d, J ) 9 Hz), 8.28 (2 H, d, J ) 9 Hz), 8.40 (1 H, s).
13C NMR (100 MHz, CDCl3): δC 7.3, 29.2, 35.0, 124.5, 125.3,
NO2) 268.1338, found 268.1339 (MNH4)+.
3-An th r a cen -9-yl-(1-d ),(2-d 2)-p r op ion ic Acid (7c). The
procedure for 7a was repeated using deuterium oxide (1.0 mL)
and the acid 6b (991 mg, 2.95 mmol) in anhydrous pyridine
(3.5 mL) to afford the acid 7c as a pale yellow solid (745 mg,
quant). Mp: 192-193 °C. IR νmax (cm-1): 3022, 1720, 1694,
1407. 1H NMR (400 MHz, DMSO-d6): δH 3.82 (1 H, m), 7.45-
7.6 (4 H, m), 8.05 (2 H, d, J ) 9 Hz), 8.28 (2 H, d, J ) 9 Hz),
8.48 (1 H, s), 12.40 (1 H, brs). 13C NMR (100 MHz, DMSO-d6):
δC 23.0 (m), 34.0 (m), 123.7, 124.8, 125.6, 125.7, 128.7, 130.8,
132.6, 173.4. HPLC (386 nm): tR ) 5.89 min (100%). MS
(ESI+): m/z 271.2 (MNH4+, 35), 256.2 (85), 212.1 (100). HR-
MS (ESI+): m/z calcd (C17H15D3NO2) 271.1526, found 271.1514
(MNH4)+.
3-An th r a cen -9-yl-(2-d 2)-p r op a n -1-ol (8a ). A solution of
lithium aluminum hydride in THF (1M, 100 mL, 100 mmol)
was added steadily, dropwise to a solution of the propionic acid
7b (22.2 g, 88.0 mmol) in THF (500 mL) with ice-bath cooling.
The mixture was warmed to room temperature and stirred for
16 h before being quenched with aqueous HCl solution (250
mL, 10%) and then diluted with water (100 mL). The crude
mixture was extracted with ethyl acetate, and the combined
organic extracts were washed with brine, dried (MgSO4), and
concentrated in vacuo to afford the alcohol 8a (19.8 g, 94%).
Mp: 99-100 °C. IR νmax (cm-1): 3650, 2885, 1043. 1H NMR
(400 MHz, CDCl3): δH 3.72 (2 H, s), 3.82 (2 H, s), 7.45-7.6 (4
H, m), 8.00 (2 H, d, J ) 9 Hz), 8.30 (2 H, d, J ) 9 Hz), 8.34 (1
126.2, 126.6, 129.7, 130.1, 132.0, 133.2. HPLC (386 nm): tR
)
7.37 min (100%). MS (ESI+): M+, 346.1. Anal. Calcd for
C
17H15I: C, 58.98; H, 4.37. Found: C, 58.83; H, 4.30.
Meth yl 4-(3-ter t-Bu toxyca r bon yla m in op r op ylsu lfa m -
oyl)-3-n itr oben zoa te (10). A suspension of the sulfonyl
chloride 3 (5.19 g, 19.4 mmol) in dichloromethane (10 mL) was
added to a stirring solution of N-BOC-1,3-diaminopropane
(3.72 mL, 21.3 mmol) and DIPEA (5.06 mL, 29.1 mmol) in
dichloromethane (20 mL). After being stirred at room temper-
ature for 16 h, the mixture was diluted with dichloromethane
(100 mL) and washed successively with water, dilute aqueous
HCl (10%), saturated aqueous NaHCO3, and brine. The organic
phase was dried (MgSO4) and evaporated under reduced
pressure to afford the sulfonamide 10 as a yellow solid (7.43
g, 92%). Mp: 98-99 °C. IR νmax (cm-1): 3371, 1733, 1719, 1684,
1
1614, 1552, 1365. H NMR (400 MHz, CDCl3): δH 1.41 (9 H,
s), 1.67 (2 H, m), 3.18 (4 H, m), 4.01 (3 H, s), 4.60 (1 H, brs),
6.06 (1 H, brs), 8.19 (1 H, d, J ) 8 Hz), 8.33 (1 H, dd, J ) 2,
J . Org. Chem, Vol. 68, No. 14, 2003 5531

Andrews and Ladlow
8 Hz), 8.40 (1 H, d, J ) 2 Hz). 13C NMR (100 MHz, CDCl3): δC
27.7, 30.1, 36.4, 40.2, 52.6, 125.5, 130.5, 132.6, 134.4, 137.0,
147.4, 156.0, 163.1. HPLC (254 nm): tR ) 4.90 min (100%).
MS (ESI+): m/z 344.2 (30), 318.2 (MH+ - BOC, 15), 244.1
(65), 233.2 (30), 191.2 (30). Anal. Calcd for C16H23N3O6S: C,
46.04; H, 5.55; N, 10.07; S, 7.68. Found: C, 45.96; H, 5.22; N,
9.86; S, 7.57.
DIC (69 µL, 440 µmol), and the carboxylic acid 1 (290 mg, 466
µmol) in DMF (2 mL). The mixture was shaken at room
temperature for 18 h and then filtered, and the beads were
washed extensively with DMF, CH2Cl2, and diethyl ether to
afford the N-BOC resin 12; Kaiser test negative.
The N-BOC protecting group was removed by treating the
resin 12 with a mixture of DMF (1.25 mL) and CH2Cl2 (1.25
mL) containing water (125 µL) and phenol (250 mg). After 15
min, the resin was washed with CH2Cl2. This process was
repeated to afford the amino-resin 13; Kaiser test positive.
Analytical cleavage data using standard cleavage conditions:
Meth yl 4-[(3-An th r a cen -9-ylp r op yl)(3-ter t-bu toxyca r -
bon yla m in op r op yl)su lfa m oyl]-3-n itr oben zoa te (11). A
solution of the iodides 9a and 9b (1:1, 790 mg, 2.30 mmol) in
DMF (5 mL) was added to a mixture of the sulfonamide 10
(860 mg, 2.10 mmol) and PS-BEMP (1.40 g, 3.10 mmol) in
DMF (5 mL). The resulting mixture was stirred at room
temperature for 64 h and filtered. The filtrate was evaporated
in vacuo and purified by column chromatography eluting with
ethyl acetate/hexane eluent (3:7) to give the mixed sulfonamide
(11) as a pale yellow foam (1.17 g, 89%). IR νmax (cm-1): 3429,
F r om Resin 12. LC-MS (386 nm): tR ) 4.74 min (100%);
m/z (ESI+) MH+ 393.1, 395.1.
F r om Resin 13. LC-MS (386 nm): tR ) 4.10 min (100%);
m/z (ESI+) MH+ 293.6, 295.6.
P r ep a r a tion of th e An a lytica l Con str u ct Resin 14. The
resin 13 (from 500 mg ArgoGel-NH2) was pre-swollen with
CH2Cl2 (2 mL) and treated with a mixture of PyBOP (220 mg,
420 µmol), HOBt (60 mg, 440 µmol), and 4-[(4-formyl-3-
methoxy)phenoxy]butyric acid (94 mg, 400 µmol) in DMF (2
mL). DIPEA (140 µL, 880 µmol) was added, and the mixture
was shaken at room temperature for 18 h, filtered, and washed
extensively with DMF, CH2Cl2, and diethyl ether; Kaiser test
negative.
1
1706, 1624, 1546, 1437. H NMR (400 MHz, CDCl3): δH 1.40
(9 H, s), 1.73 (2 H, m), 1.98 (1/2 × 2 H, m), 3.09 (2 H, m), 3.36
(2 H, m), 3.50 (4 H, m), 3.98 (3 H, s), 4.70 (1H, brs), 7.40-7.50
(4 H, m), 7.78 (1 H, d, J ) 9 Hz), 7.98 (2H, d, J ) 9 Hz), 8.01
(1H, d, J ) 9 Hz), 8.10 (2 H, d, J ) 9 Hz), 8.13 (1 H, s), 8.32
(1 H, s). 13C NMR (100 MHz, CDCl3): δC 22.7, 22.9, 27.4, 29.5,
35.6, 43.1, 45.0, 45.2, 51.4, 77.6, 122.1, 123.2, 123.4, 124.2,
124.5, 127.7, 127.8, 129.2, 129.8, 130.4, 131.0, 133.0, 135.0,
146.0, 154.8, 161.8. HPLC (386 nm): tR ) 7.08 min (100%).
MS (ESI+): (MH - BOC)+, 536.3, 538.3.
Analytical cleavage data using standard conditions:
F r om Resin 14. LC-MS (386 nm): tR ) 3.37 min (100%);
m/z (ESI+) MH+ 513.5, 515.3.
The H2- and D2-sulfonamides were also prepared separately
using a similar procedure and gave the following analytical
data:
H2-Sulfonamide (11). HPLC (386 nm): tR ) 7.08 min (100%).
HR-MS (ESI+): m/z calcd (C33H37N3NaO8S) 658.2199, found
658.2211 (MNa)+.
D2-Sulfonamide (11). HPLC (386 nm): tR ) 7.07 min (100%).
HR-MS (ESI+): m/z calcd (C33H35D2N3NaO8S) 660.2325, found
660.2341 (MNa)+.
P r ep a r a tion of Ba se Resin 15. ArgoGel-NH2 (500 mg,
0.22 mmol) was washed with piperidine/CH2Cl2/DMF (6:7:7,
10 mL), filtered, and washed extensively with DMF, CH2Cl2,
and diethyl ether. The resin was pre-swollen with CH2Cl2 (2
mL) and treated with a mixture of PyBOP (220 mg, 420 µmol),
HOBt (60 mg, 440 µmol), and 4-[(4-formyl-3-methoxy)phenoxy]-
butyric acid (94 mg, 400 µmol) in DMF (2 mL). DIPEA (140
µL, 880 µmol) was added, and the mixture was shaken at room
temperature for 18 h, filtered, and washed extensively with
DMF, CH2Cl2, and diethyl ether; Kaiser test negative.
4-[(3-An th r acen -9-yl-pr opyl)(3-ter t-bu toxycar bon ylam i-
n op r op yl)su lfa m oyl]-3-n itr oben zoic Acid (1). Aqueous
sodium hydroxide solution (5.0 mL × 2.0 M, 10.0 mmol) was
added dropwise to a solution of the ester 11 (2.10 g, 3.40 mmol)
in THF (20 mL) at 0 °C. The mixture was stirred at room
temperature for 1.5 h and then acidified by addition of dilute
aqueous HCl (10%) to pH 3. The resulting mixture was
extracted with ethyl acetate, and the combined organic phases
were washed with brine, dried (MgSO4), and evaporated under
reduced pressure to afford the acid 1 as a yellow foam (2.10 g,
Gen er a l P r oced u r e for F or m a tion of F m oc Der iva -
tives of Ald eh yd e Resin s 14 a n d 15. A solution of 9-fluor-
enylmethyl carbazate (90 mg, 350 µmol) in DMF (2.2 mL) and
AcOH (1.0 mL) was prepared. The resulting mixture (1.0 mL)
was added to each of the aldehyde resins 14 and 15 (approx
35 µmol) pre-swollen in DMF (1.0 mL), and the resins were
shaken for 16 h at room temperature. The resins were then
filtered, washed extensively with DMF, CH2Cl2, and diethyl
ether, and dried in vacuo to afford the corresponding resin-
bound Fmoc hydrazones. Fmoc numbers were determined by
cleavage of a known quantity of resin with piperidine/DMF
mixture (1:1) and determination of the absorbance at 300 nm:
1
100%). IR νmax (cm-1): 2937, 1704, 1365. H NMR (400 MHz,
DMSO-d6): δH 1.29 (9 H, s), 1.63 (2 H, m), 1.80 (1/2 × 2 H, m),
2.89 (2 H, m), 3.30 (2 H, m), 3.48 (2 H, m), 3.59 (2 H, m), 6.75
(1 H, brt), 7.4-7.50 (4 H, m), 8.0-8.10 (3 H, m), 8.21 (3 H, m),
8.37 (1 H, s), 8.48 (1 H, s). 13C NMR, (100 MHz, DMSO-d6):
δC 22.3, 22.5, 26.3, 26.7, 27.6, 35.6, 43.5, 45.1, 45.2, 75.7, 122.2,
123.0, 123.2, 123.8, 124.0, 127.1, 127.2, 128.7, 129.3, 130.8,
Construct resin 14 loading: 0.25 mmol g-1
Base resin 15 loading: 0.26 mmol g-1
.
.
Gen er a l P r oced u r e for Red u ctive Am in a tion s of Ald e-
h yd e Resin s: P r ep a r a tion of Resin s 17{1-3} a n d 18{1-
3}. The aldehyde resins 14 and 15 (approximately 3 × 60 µmol
each) were washed with trimethyl orthoformate and filtered.
The resins were then pre-swollen with a mixture of TMOF/
NMP (4:1 v/v, 1 mL) and shaken with an amine 16 (700 µmol)
and AcOH (12 µL, 200 µmol) for 2 h at room temperature. The
resins were filtered and washed with CH2Cl2, pre-swollen with
CH2Cl2 (1 mL), and shaken with Me4NBH(OAc)3 (92 mg, 350
µmol) and AcOH (12 µL, 200 µmol) for 1 h.
The resins were again washed with CH2Cl2 and TMOF, pre-
swollen with TMOF/NMP mixture (4:1 v/v, 1 mL), and shaken
with the same amine 16 (700 µmol) and AcOH (12 µL, 200
µmol) for a further 2 h. Once more, the resins were filtered
and washed with CH2Cl2, pre-swollen with CH2Cl2, and shaken
with Me4NBH(OAc)3 (92 mg, 350 µmol) and AcOH (12 µL, 200
µmol) for 16 h. The resins were filtered and washed extensively
with DMF, CH2Cl2, and diethyl ether to afford the amino-
resins 17{1-3} and 18{1-3}.
131.7, 133.3, 134.3, 145.6, 153.7, 162.6. HPLC (386 nm): tR
)
6.84 min (100%). LC-MS (386 nm ESI-): tR ) 5.90 min (100%),
MH- 620.1, 622.2. HR-MS (ES+): m/z calcd (C32H35N3O8NaS,
C
32H33D2N3O8NaS) 644.2043, 646.2168, found 644.2048,
646.2160 (MNa+).
Sta n d a r d An a lytica l Clea va ge P r oced u r e. A stock
cleavage solution was prepared from 2-mercaptoethanol (40
µL, 600 mmol) and sodium methoxide solution (1.0 mL × 0.5
M in MeOH). A small sample of resin beads was removed (10-
20 beads) and incubated with the cleavage solution (30 µL)
for 10 min at room temperature and then filtered. The filtrate
was diluted with CH3CN (100 µL) and analyzed by LC-MS
(ESI() with UV detection at 386 nm.
P r ep a r a tion of Con str u ct Resin s 12 a n d 13. ArgoGel-
NH2 resin (0.43 mmol g-1, 500 mg, 0.22 mmol) was washed
with piperidine/CH2Cl2/DMF (6:7:7, 10 mL), filtered, and
washed extensively with DMF, CH2Cl2, and diethyl ether. The
resin was pre-swollen with CH2Cl2 (2 mL) and then treated
with a mixture of 1-hydroxybenzotriazole (60 mg, 440 µmol),
5532 J . Org. Chem., Vol. 68, No. 14, 2003

Analysis and Development of Solid-Phase Chemistries
Analytical cleavage data using standard cleavage conditions:
F r om Resin 17{1}. LC-MS (386 nm): tR ) 3.13 min
(>95%); m/z (ESI+) MH+ 618.6, 620.3.
which were quantified by 1H NMR comparing peak areas
relative to residual DMSO in DMSO-d6 precalibrated with
p-nitrophenol.
F r om Resin 17{2}. LC-MS (386 nm): tR ) 3.10 min (91%);
24{1,1}. 1H NMR (400 MHz, DMSO-d6): δH 2.24 (3 H, s),
4.41 (2 H, d J ) 6 Hz), 7.10 (2 H, d, J ) 8 Hz), 7.15 (1 H, m),
7.19 (2 H, d J ) 8 Hz), 7.60 (2 H, m), 7.72 (2 H, m), 7.90 (2 H,
m), 8.99 (1 H, t J ) 6 Hz). LC-MS (254 nm): tR ) 5.61 min
(>95%); m/z (ESI+) MH+ 308.2.
m/z (ESI+) MH+ 570.4, 572.4.
F r om Resin 17{3}. LC-MS (386 nm): tR ) 3.20 min (93%);
m/z (ESI+) MH+ 618.5, 620.5.
Gen er a l P r oced u r e for Acyla tion s of Am in o-Resin s
w ith 4-Iod oben zoyl Ch lor id e: P r ep a r a tion of Resin s 19-
{1-3} a n d 20{1-3}. To the amino-resins 17{1-3} and 18{1-
3} (approximately 3 × 60 µmol each), pre-swollen in DCM (1
mL), were added 4-iodobenzoyl chloride (48 mg, 180 µmol) and
DIPEA (63 µL, 360 µmol). The suspensions were shaken at
room temperature for 2 h, filtered, and washed extensively
with DMF, CH2Cl2, and diethyl ether.
1
24{2,1}. H NMR (400 MHz, DMSO-d6): δH 0.88 (6 H, d, J
) 7 Hz), 1.83 (1 H, m), 3.07 (2 H, m), 7.15 (1 H, m), 7.59 (2 H,
m), 7.70 (2 H, m), 7.86 (2 H, m), 8.45 (1 H, t, J ) 6 Hz). LC-
MS (254 nm): tR ) 5.09 min (>95%); m/z (ESI+) MH+ 260.4.
1
24{3,1}. H NMR (400 MHz, DMSO-d6): δH 2.83 (2 H, t, J
) 7 Hz), 3.45 (2 H, m), 7.1-7.3 (6 H, m), 7.60 (2 H, m), 7.70 (2
H, m), 7.83 (2 H, m), 8.57 (1 H, t, J ) 6 Hz). LC-MS (254
nm): tR ) 5.46 min (>95%); m/z (ESI+) MH+ 308.3.
24{1,2}. 1H NMR (400 MHz, DMSO-d6): δH 2.24 (3 H, s),
4.41 (2 H, d, J ) 8 Hz), 7.12 (2 H, d, J ) 8 Hz), 7.20 (2 H, d,
J ) 8 Hz), 7.27-7.33 (2 H, m), 7.57 (1 H, s), 7.65 (2 H, m), 8.0
(4 H, s), 9.10 (1 H, t, J ) 8 Hz). LC-MS (254 nm): tR ) 6.28
min (>95%); m/z (ESI+) MH+ 342.0.
Analytical cleavage data using standard cleavage conditions:
F r om Resin 19{1}. LC-MS (386 nm): tR ) 4.10 min
(>95%); m/z (ESI+) MH+ 848.7, 850.3.
F r om Resin 19{2}. LC-MS (386 nm): tR ) 4.04 min (91%);
m/z (ESI+) MH+ 800.3, 802.3.
F r om Resin 19{3}. LC-MS (386 nm): tR ) 4.11 min (88%);
m/z (ESI+) MH+ 848.3, 850.3.
1
24{2,2}. H NMR (400 MHz, DMSO-d6): δH 0.88 (6 H, d, J
Gen er a l P r oced u r e for Su zu k i Cou p lin gs: P r ep a r a -
tion of Resin s 22{1-3,1-3} a n d 23{1-3,1-3}. To the iodo-
resins 19{1-3} and 20{1-3} (approximately 3 × 20 µmol each)
were added solutions of the boronic acids 21{1-3} (100 µmol)
in DMF (350 µL), K3PO4 (50 µmol) in H2O (150 µL), and Pd-
(PPh3)4 (4 µmol) in DMF (500 µL). The vessels were flushed
with nitrogen gas and sealed. The suspensions were stirred
and heated to 80 °C for 1.5 h, filtered, and washed extensively
with DMF, CH2Cl2, and diethyl ether.
) 7 Hz), 1.84 (1 H, m), 3.08 (2 H, t, J ) 6 Hz), 7.25-7.36 (2 H,
m), 7.56 (1 H, m), 7.66 (2 H, m), 7.98 (4 H, m), 8.57 (1 H, t, J
) 6 Hz). LC-MS (254 nm): tR ) 5.87 min (95%); m/z (ESI+)
MH+ 294.2.
1
24{3,2}. H NMR (400 MHz, DMSO-d6): δH 2.83 (2 H, t, J
) 8 Hz), 3.46 (2 H, m), 7.16-7.36 (7 H, m), 7.56 (1 H, m), 7.66
(2 H, m), 7.92-8.0 (4 H, m), 8.69 (1 H, t, J ) 6 Hz). LC-MS
(254 nm): tR ) 6.14 min (>95%); m/z (ESI+) MH+ 342.1.
24{1,3}. 1H NMR (400 MHz, DMSO-d6): δH 2.24 (3 H, s),
3.74 (3 H, s), 4.42 (2 H, d, J ) 6 Hz), 7.01 (1H, m), 7.10 (2 H,
m), 7.18 (3 H, m), 7.27-7.38 (2 H, m), 7.53 (2 H, m), 7.89 (2
H, m), 9.01 (1 H, t, J ) 6 Hz). LC-MS (254 nm): tR ) 5.54
min (>95%); m/z (ESI+) MH+ 332.2.
Analytical cleavage data using standard cleavage conditions:
F r om Resin 22{1,1}. LC-MS (386 nm): tR ) 4.16 min
(>95%); m/z (ESI+) MH+ 804.7, 806.5.
F r om Resin 22{1,2}. LC-MS (386 nm): tR ) 4.44 min
(89%); m/z (ESI+) MH+ 838.7, 840.5.
24{2,3}. H NMR (400 MHz, DMSO-d6): δH 0.88 (6 H, d, J
1
F r om Resin 22{1,3}. LC-MS (386 nm): tR ) 4.30 min
(80%); m/z (ESI+) MH+ 790.4, 792.4.
) 8 Hz), 1.84 (1 H, m), 3.07 (2 H, m), 3.74 (3 H, s), 7.02 (1 H,
m), 7.11 (1 H, m), 7.30 (1 H, m), 7.35 (1 H, m), 7.42 (2 H, m),
F r om Resin 22{2,1}. LC-MS (386 nm): tR ) 4.10 min
7.82 (2 H, m), 8.48 (1 H, t, J ) 6 Hz). LC-MS (254 nm): tR )
(88%); m/z (ESI+) MH+ 756.8, 758.4.
5.04 min (>95%); m/z (ESI+) MH+ 284.4.
1
F r om Resin 22{2,2}. LC-MS (386 nm): tR ) 4.36 min
(91%); m/z (ESI+) MH+ 838.5, 840.5.
24{3,3}. H NMR (400 MHz, DMSO-d6): δH 2.83 (2 H, m),
3.48 (2 H, m), 3.74 (3 H, s), 7.01 (1 H, m), 7.10 (1 H, m), 7.16-
7.30 (7 H, m), 7.51 (2 H, m), 7.80 (2 H, m), 8.57 (1 H, t, J ) 6
Hz). LC-MS (254 nm): tR ) 5.39 min (>95%); m/z (ESI+) MH+
332.2.
F r om Resin 22{2,3}. LC-MS (386 nm): tR ) 4.23 min
(91%); m/z (ESI+) MH+ 828.5, 830.5.
F r om Resin 22{3,1}. LC-MS (386 nm): tR ) 4.16 min
(88%); m/z (ESI+) MH+ 804.5, 806.5.
F r om Resin 22{3,2}. LC-MS (386 nm): tR ) 4.11 min
Ack n ow led gm en t. We thank GlaxoSmithKline for
financial support of this work (industrial placement to
S.P.A.) and Drs. Miles Congreve and J an Scicinski for
helpful discussions.
(88%); m/z (ESI+) MH+ 780.5, 782.5.
F r om Resin 22{3,3}. LC-MS (386 nm): tR ) 4.17 min
(88%); m/z (ESI+) MH+ 828.6, 830.6.
Gen er a l P r oced u r e for Resin Clea va ge To Affor d
Ca r boxa m id es (24{1-3,1-3}). The resins 22{1-3,1-3} and
23{1-3,1-3} (approximately 9 × 20 µmol each) were shaken
with TFA/TES/H2O (500 µL, 90:5:5) at room temperature for
1 h, filtered, and washed with CH2Cl2 (2 × 1 mL). The
procedure was repeated, and combined filtrates were evapo-
rated under reduced pressure to afford the carboxamides 24,
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra for all compounds described that are not attached to
resin or obtained following analytical cleavage. This material
is available free of charge via the Internet at http://pubs.acs.org.
J O034340P
J . Org. Chem, Vol. 68, No. 14, 2003 5533