Noncovalent inhibitors of human leukocyte elastase based on the 4-imidazolidinone scaffold

Article abstract of DOI:10.1016/j.bmc.2003.08.030

A central problem associated with the design of enzyme inhibitors in general, and serine protease inhibitors in particular, is the identification of templates capable of binding to the active site of an enzyme in a predictable and substrate-like fashion, orienting appended recognition elements in a correct spatial relationship so that favorable binding interactions with multiple sites are achieved. Described herein for the first time is the design of noncovalent inhibitors of human leukocyte elastase that employs a functionalized 4-imidazolidinone scaffold.

Full text of DOI:10.1016/j.bmc.2003.08.030

Bioorganic & Medicinal Chemistry 11 (2003) 5149–5153
Noncovalent Inhibitors of Human Leukocyte Elastase Based on
the 4-Imidazolidinone Scaffold
Liuqing Wei, Xiangdong Gan, Jiaying Zhong, Kevin R. Alliston and William C. Groutas*
Department of Chemistry, Wichita State University, Wichita, KS 67260, USA
Received 8July 2003; accepted 15 August 2003
Abstract—A central problem associated with the design of enzyme inhibitors in general, and serine protease inhibitors in particular,
is the identification of templates capable of binding to the active site of an enzyme in a predictable and substrate-like fashion,
orienting appended recognition elements in a correct spatial relationship so that favorable binding interactions with multiple sites
are achieved. Described herein for the first time is the design of noncovalent inhibitors of human leukocyte elastase that employs a
functionalized 4-imidazolidinone scaffold.
# 2003 Elsevier Ltd. All rights reserved.
Inhibitor design
Introduction
Proteases of mammalian, viral, bacterial and parasitic
origin are directly involved or have been implicated in
the pathogenesis of a range of human diseases,1,2 con-
sequently, mammalian and non-mammalian serine,
cysteine, aspartic and metallo-proteases have been the
subject of intense investigation in recent years.3 The
development of agents capable of modulating the activ-
ity of proteases may lead to the emergence of new ther-
apeutic interventions.
Based on the results of preliminary computational and
modeling studies, as well as insights gained from the
aforementioned studies with the 1,2,5-thiadiazolidin-3-
one 1,1 dioxide scaffold, we hypothesized that append-
ing recognition elements P1, R2 and R3 to a planar or
near planar cyclic system in a way that these elements
bear the same vector relationship as when similarly
appended to the 1,2,5-thiadiazolidin-3-one 1,1 dioxide
scaffold would yield a series of heterocyclic scaffolds
[represented by structure (I)] capable of binding to the
active site of (chymo)trypsin-like serine proteases, lead-
ing to inhibition of these enzymes. The evolution of the
design process is summarized in Figure 1. Described
herein are the results of preliminary studies related to
the use of substituted 4-imidazolidinones (Ib) in the
inhibition of human leukocyte elastase that lend sup-
port to the aforementioned hypothesis, as well as pave
the way toward placing the design of protease inhibitors
on a more secure structural and biochemical footing.
In recent studies we have described the structure-based
design of a novel heterocyclic scaffold and its use in the
mechanism-based inactivation of (chymo)trypsin-like
serine proteases.4ꢀ8 We have furthermore demonstrated
that the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold
(Ia) (Fig. 1) is a versatile core structure that can be used
in (a) the design of covalent and noncovalent inhibitors
of serine proteases and to fashion inhibitors that show
absolute selectivity between neutral, basic and acidic
serine proteases; (b) is amenable to the construction of
libraries for lead identification and optimization and, (c)
makes possible the attachment and optimal spatial
orientation of recognition elements, thereby allowing
the exploitation of favorable binding interactions with
both the S and S0 subsites of a target protease.
Chemistry
Compounds 6–16 were synthesized as illustrated in
Scheme 1 and are listed in Tables 1 and 2. As indicated
in Scheme 1, the amino acid derivative selected to serve
as the starting material is dictated by the primary sub-
strate specificity of the target protease. Likewise, the
nature of R2 and R3 was chosen on the basis of what is
known about the active site subsites of HLE (vide
*Corresponding author. Tel.: +1-316-978-7374; fax: +1-316-978
3431; e-mail: bill.groutas@wichita.edu
0968-0896/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2003.08.030

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L. Wei et al. / Bioorg. Med. Chem. 11 (2003) 5149–5153
Table 1. Structures of compounds 6–16
X=
Cbz, P1=isobutyl, R2=H, R3=COOt-Bu, (6)
Cbz, P1=isobutyl, R2=H, R3=COOCH3, l-isomer (7)
Cbz, P1=isobutyl, R2=H, R3=COOCH3, d-isomer (8)
Cbz, P1=isobutyl, R2=H, R3=COOH (9)
Cbz, P1=isobutyl, R2=OH, R3=COOCH3 (10)
Cbz, P1=isobutyl, R2=R3=H (11)
H, P1=isobutyl, R2=R3=H (12)
CH3SO2, P1=isobutyl, R2=R3=H (13)
CH3CH2OCO, P1=isobutyl, R2=R3=H (14)
Cbz, P1=isobutyl, R2=R3=H (15)
Figure 1. Evolution of the design of inhibitor (I) beginning with the
human leukocyte elastase–turkey ovomucoid inhibitor (HLE–TOMI)
complex.
Cbz, P1=isobutyl, R2=H, R3=COOCH3, l-isomer (16)
strate concentrations: 2.3315 ꢁ 10ꢀ4 M and 1.1658 ꢁ
10ꢀ4 M). All rates were determined in triplicate. The
inverse of the average velocities was plotted against the
final inhibitor concentrations and the KI determined
from the intersection of the three lines (each R2 >0.99).
A representative 1/v versus [I] plot is shown in Figure 2.
Results and Discussion
The rational and successful development of protease
inhibitors that exhibit high enzyme selectivity and
potency is largely dependent on the design of highly
functionalized templates that are capable of exploiting
subtle differences in the topography of the active sites of
the target enzymes. This is of particular importance in
the case of proteases which have the same or very similar
primary substrate specificity such as, for example, the
serine proteases of the coagulation cascade (thrombin,
factor Xa, plasmin, etc.), or the neutrophil-derived
enzymes human leukocyte elastase (HLE) and proteinase
3 (PR 3). In such cases, attainment of maximal enzyme
selectivity is possible only if subtle structural differences
in the subsites on either side of the scissile bond can be
exploited. Accomplishing this requires the availability of
templates that are capable of docking to the active site in
a predictable and substrate-like fashion, at the same time
orienting appended binding elements toward the S2–Sn
and S0 subsites.10 Exploitation of differences in the S and
S0 subsites can then be achieved by structural modifi-
cation of the appended recognition elements.
Scheme 1. (a) IBCF/NMM then Gly-OCH3 (HCl); (b) HCl/dioxane;
(c) Cbz-l-Val-l-prolinal/NaBH (OAc)3; (d) 37% aq HCHO; (e) aq
KOH; (f) CDI/THF then RNH2.
infra). A representative synthesis is described in the
Experimental.
Biochemical Studies
The inhibitory activity of compounds 6–16 was eval-
uated by determining the KI using Dixon plots9 and the
results are listed in Table 3. A representative experiment
was carried out according to the following procedure: to
a thermostatted solution of 930 mL 0.1 M HEPES buffer
containing 0.5 M NaCl, pH 7.25, was added DMSO
(50 mL), human leukocyte elastase (10 mL solution in
0.05 M sodium acetate buffer containing 0.5 M NaCl,
pH 5.5, for a final enzyme concentration of 70 nM) and,
lastly, 10 mL methoxysuccinyl-Ala-Ala-Pro-Val p-nitro-
anilide in DMSO for a final substrate concentration of
0.70 mM, and the rate of hydrolysis was determined by
monitoring the absorbance at 410 nm for 2 min. The
experiment was repeated in the presence of varying
amounts of inhibitor 11 (10–50 mL) at a constant final
concentration of DMSO (5%), and the rates of sub-
strate hydrolysis determined.
HLE, a neutrophil-derived serine protease that has been
implicated in inflammatory diseases11,12 and cancer
metastasis,13,14 was chosen as a representative serine
protease for exploring the aforementioned ideas. HLE is
known to interact with its substrate through a series of
hydrogen bonds and hydrophobic binding interactions,
as illustrated in Figure 3.15
Based on earlier structure–activity relationship studies
with the 1,2,5-thiadiazolidin-3-one 1,1 dioxide scaffold,
as well as modeling and computational studies, we specu-
The series of experiments described above was repeated
at two additional substrate concentrations (final sub-

L. Wei et al. / Bioorg. Med. Chem. 11 (2003) 5149–5153
5151
Table 2. Spectral data of inhibitors 6-16
Compd
1H NMR Data ( d )
MF (anal.)
Mr
6
7
8
9
(CDCl3) 0.85–1.00 (m, 12H), 1.32–1.58 (m, 12H), 1.75–2.00 (m, 6H), 2.39–2.42 (m, 1H),
2.76–2.90 (m, 1H), 3.02–3.18(m, 3H), 3.40–3.58(m, 1H), 3.63–3.72 (m, 1H), 3.80–3.98(m, 3H),
4.16–4.25 (m, 1H), 4.26–4.37 (m,1), 4.52–4.56 (d, 1H), 4.67–4.74 (m, 1H), 5.00–5.18(m, 2H),
5.58–5.63 (d, 1H), 6.43–6.48 (d, 1H), 7.10–7.40 (m, 10H)
C40H57N5O7
719.91
(CDCl3) 0.82–1.04 (m, 12H), 1.35–1.45 (m, 1H), 1.47–1.59 (m, 1H), 1.64–2.02 (m, 6H),
2.35–2.42 (m, 1H), 2.72–2.90 (m, 1H), 3.02–3.20 (m, 3H), 3.40–3.52 (m, 1H), 3.63–3.74 (m, 4H),
3.80–3.97 (m, 3H), 4.20–4.26 (m, 1H), 4.27–4.37 (m,1H), 4.52–4.56 (d, 1H), 4.78–4.86 (m, 1H),
5.04–5.14 (m, 2H), 5.52–5.63 (d, 1H), 6.52–6.60 (d, 1H), 7.05–7.40 (m, 10H)
C37H51N5O7
C37H51N5O7
C36H50ClN5O7
677.83
677.83
700.26
(CDCl3) 0.82–1.04 (m, 12H), 1.35–1.45 (m, 1H), 1.47–1.59 (m, 1H), 1.64–2.02 (m, 6H),
2.35–2.42 (m, 1H), 2.72–2.90 (m, 1H), 3.02–3.20 (m, 3H), 3.40–3.52 (m, 1H), 3.63–3.74 (m, 4H),
3.75–3.81 (m, 1H), 3.90–4.05 (m, 2H), 4.23–4.35 (m, 2H), 4.52–4.56 (d, 1H), 4.78–4.86 (m, 1H),
5.04–5.14 (m, 2H), 5.52–5.63 (d, 1H), 6.52–6.60 (d, 1H), 7.05–7.40 (m, 10H)
(CDCl3) 0.81–1.00 (m, 12H), 1.32–1.37 (s, 1H), 1.56–1.72 (br m, 2H), 1.74–2.08 (m, 6H),
2.45–2.52 (s, 1H), 2.85–3.01 (m, 1H), 3.02–3.16 (m, 2H), 3.18–3.40 (br m, 1H),
3.43–3.60 (m, 1H), 3.63–3.80 (m, 1H), 3.83–3.95 (m, 2H), 3.95–4.07 (m, 1H), 4.09–4.20 (m, 1H),
4.37–4.50 (m, 2H), 4.72–4.83 (m, 1H), 4.97–5.14 (m, 2H), 7.15–7.42 (m, 10H), 7.50–7.63 (d, 1H),
8.54–8.60 (s, 1H)
10
11
(CDCl3) 0.84–1.06 (m, 12H), 1.34–1.45 (m, 1H), 1.47–1.57 (m, 1H), 1.77–2.00 (m, 6H),
2.35–2.43 (m, 1H), 2.78–2.91 (m, 1H), 2.95–3.16 (m, 2H), 3.18–3.23 (m, 1H), 3.48–3.60 (m, 2H),
3.72–3.80 (m, 4H), 3.83–4.13 (m, 2H), 4.18–4.32 (m, 2H), 4.36–4.42 (m, 1H), 4.75–4.83 (m, 1H),
5.02–5.18(m, 2H), 5.55–5.63 (m, 1H), 6.54–6.57 (d, 1H), 6.70–7.40 (m, 9H)
C37H51N5O8
693.83
619.79
(CDCl3) 0.82–1.04 (m, 12H), 1.33–1.45 (m, 1H), 1.53–1.60 (m, 1H), 1.70–2.02 (m, 6H),
2.34–2.43 (m, 1H), 2.72–2.93 (m, 3H), 3.10–3.19 (t, 1H), 3.37–3.62 (m, 3H), 3.63–3.80 (m, 1H),
3.80–4.02 (m, 3H), 4.12–4.38 (m, 2H), 4.52–4.62 (m, 1H), 5.08–5.15 (m, 2H), 5.44–5.53 (m, 1H),
6.12–6.22 (m, 1H), 6.95–7.42 (m, 10H)
C35H49N5O5
12
13
(CDCl3) 0.82–1.04 (m, 12H), 1.30–1.45 (m, 1H), 1.47–1.60 (m, 1H), 1.60–2.01 (m, 8H),
2.37–2.43 (m, 1H), 2.72–2.92 (m, 3H), 3.10–3.19 (t, 1H), 3.24–3.33 (d, 1H), 3.36–4.00 (m, 4H),
3.80–4.00 (m, 3H), 4.20–4.33 (m, 1H), 4.52–4.58 (m, 1H), 6.24–6.32 (m, 1H), 7.09–7.36 (m, 5H)
C27H43N5O3
485.66
563.75
(CDCl3) 0.80–1.04 (m, 12H), 1.30–1.42 (m, 1H), 1.42–1.60 (m, 1H), 1.73–2.00 (m, 6H),
2.37–2.43 (m, 1H), 2.70–2.88 (m, 6H), 3.10–3.19 (t, 1H), 3.35–3.65 (m, 4H), 3.67–3.80 (m, 1H),
3.80–3.97 (m, 3H), 4.17–4.33 (m, 1H), 4.52–4.58 (m, 1H), 5.43–5.56 (m, 1H), 6.30–6.40 (m, 1H),
7.09–7.32 (m, 5H)
C28H45N5O5S
14
15
16
(CDCl3) 0.65–0.96 (m, 12H), 1.05–1.25 (m, 3H), 1.26–1.38(m, 1H), 1.40–1.56 (m, 1H),
1.73–1.87 (m, 6H), 2.30–2.43 (m, 1H), 2.64–2.82 (m, 3H), 3.00–3.15 (t, 1H), 3.24–3.55 (m, 3H),
3.60–3.67 (m, 1H), 3.68–3.80 (m, 1H), 3.82–3.94 (m, 2H), 3.95–4.08 (m, 2H), 4.13–4.26 (m, 2H),
4.42–4.53 (m, 1H), 5.33–5.40 (d, 1H), 6.18–6.23 (m, 1H), 7.00–7.26 (m, 5H)
C30H47N5O5
C34H47N5O5
C36H49N5O7
557.72
605.77
663.8
(CDCl3) 0.78–1.05 (m, 12H), 1.70–2.06 (m, 6H), 2.40–2.64 (m, 1H), 2.72–2.90 (m, 2H),
1.92–3.00 (m, 1H), 3.04–3.16 (m, 1H), 3.38–3.62 (m, 3H), 3.63–3.75 (m, 1H), 3.77–3.90 (m, 2H),
3.91–4.04 (m, 1H), 4.12–4.22 (m, 1H), 4.25–4.35 (m, 1H), 4.45–4.50 (m, 1H), 4.96–5.15 (m, 2H),
5.50–5.63 (m, 1H), 6.30–6.40 (m, 1H), 7.07–7.40 (m, 10H)
(CDCl3) 0.82–1.04 (m, 12H), 1.80–2.04 (m, 6H), 2.35–2.50 (m, 1H), 2.80–3.00 (m, 1H),
3.02–3.20 (m, 3H), 3.42–3.52 (m, 1H), 3.63–3.75 (m, 4H), 3.80–4.00 (m, 3H), 4.15–4.22 (m, 1H),
4.27–4.37 (m, 1H), 4.52–4.56 (d, 1H), 4.79–4.87 (m, 1H), 5.02–5.12 (m, 2H), 5.52–5.60 (d, 1H),
6.56–6.60 (d, 1H), 7.05–7.40 (m, 10H)
lated that derivatives based on the 4-imidazolidinone
template may exhibit inhibitory activity toward HLE and
related (chymo)trypsin-like proteases. Since many of the
known inhibitors of HLE such as, for example, peptidyl
trifluoromethylketones and related transition state inhibi-
tors,16,17 incorporate in their structures a -Val-Pro- seg-
ment that interacts with the S3 and S2 subsites, we decided
to attach this sequence to the heterocyclic template. An
aromatic amino acid was also attached to the inhibitor in
order to exploit favorable binding interactions with
Phe-41, located near the S02 subsite.
Table 3. Inhibitory activity of compounds 6–16 toward human
leukocyte elastase
Compd
KI (mM)
6
7
65.0
18.0
8
9
40.0
70.0
10
11
12
13
14
15
16
40.0
12.0
Inactive
Inactive
Inactive
9.0
The results summarized in Table 2 clearly show that the
4-imidazolidinone template can be used in the design of
22.0

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L. Wei et al. / Bioorg. Med. Chem. 11 (2003) 5149–5153
Figure 2. Dixon plot showing the inhibition of human leukocyte elastase by compound 11.
the synthesized compounds were recorded on a Varian
XL-300 or XL-400 spectrometer. The synthesized com-
pounds were purified using flash chromatography. A
Hewlett-Packard diode array UV/VIS spectro-
photometer was used in the enzyme assays and inhibi-
tion studies. Human leukocyte elastase was purchased
from Elastin Products Co., Owensville, MO, USA.
Methoxysuccinyl Ala-Ala-Pro-Val p-nitroanilide was
purchased from Sigma Chemicals Co., St. Louis, MO,
USA. 2 M oxalyl chloride in methylene chloride was
purchased from Aldrich Chemical Co.
Figure 3. Main-chain and side-chain binding interactions between a
substrate or inhibitor and the active site of HLE.
inhibitors of human leukocyte elastase. While the
potency of many of the compounds was modest, many
of the compounds did possess inhibitory activity toward
HLE. Compounds 11 and 15 (Table 2), having a phe-
nethylamine moiety oriented toward the S0 subsites and
differing only in the nature of the primary specificity
residue (P1=isobutyl and isopropyl, respectively), were
found to have the highest potency (KI 12.0 and 9.0 mM,
respectively). Interestingly, removal and/or replacement
of the Cbz group resulted in total loss of inhibitory
activity (Table 2, compounds 12–14). Replacement of 2-
phenethylamine with (l) phenylalanine methyl ester
yielded 7 which was near equipotent to compound 11.
Potency decreased 2-fold when (d) phenylalanine
methyl ester was attached at the same position.
Synthesis of compound 1. A solution of Boc-l-leucine
(40 g; 173 mmol) in dry THF (600 mL) was cooled in an
ice-bath and then treated with N-methylmorpholine
(NMM) (87.6 g; 0.80 mol). Isobutyl chloroformate
(23.6 g; 173 mmol) was added and, after stirring the
reaction mixture for 5 min, glycine methyl ester hydro-
chloride (21.6 g; 173 mmol) was added. The ice bath was
removed and the reaction mixture was stirred for 1 h.
The solvent was removed using a rotary evaporator and
the residue was treated with ethyl acetate (600 mL). The
resulting solution was washed with 5% aq HCl
(200 mL), 5% aq NaHCO3 (200 mL) and brine
(200 mL). The organic phase was dried over anhydrous
sodium sulfate and the solvent removed in vacuo. Eva-
poration of the solvent left a crude solid which was
purified by recrystalization to yield a white solid
(36.36 g; 70% yield), mp 123–124 ꢂC. 1H NMR (CDCl3)
d 0.91–0.96 (m, 6H), 1.50–1.55 (m, 1H), 1.63–1.73
(dd, 2H), 3.75 (s, 3H), 4.04–4.06 (d, 2H), 4.14–4.24 (br s,
1H), 4.98–5.02 (d, 2H), 6.75–6.80 (br s, 1H).
In summary, these studies have demonstrated that deriva-
tives based on the 4-imidazolidinone scaffold function as
inhibitors of HLE and, possibly, related serine proteases.
Furthermore, the results of these studies, as well as related
studies in progress,18 provide tentative support to the
hypothesis that surrogate scaffolds with appended
recognition elements oriented in space the same way as
when appended to the 1,2,5-thiadiazolidin-3-one 1,1
dioxide scaffold, exhibit protease inhibitory activity.
Synthesis of compound 2. A solution of 1 (33.86 g;
112 mmol) in dry dioxane (154 mL) was treated with dry
hydrogen chloride (280 mL 4.0 M HCl in dioxane)
dropwise. After stirring for 3 h, the solvent was removed
on the rotovac and the residue washed with ethyl ether
(3 ꢁ 200 mL). Residual ethyl ether was removed in
vacuum, yielding a light-yellow hygroscopic foam
(32.70 g; 100% yield) that was used in the next step
without further purification. 1H NMR (acetone-d6) d
0.98–1.10 (m, 6H), 1.78–1.94 (m, 2H), 1.95–2.02 (m,
1H), 3.74–3.78(s, 3H), 4.02–4.12 (d, 2H), 4.41–4.46 (t,
1H), 8.18–8.23 (br s, 2H), 8.60–8.66 (br s, 1H).
Experimental
General
Melting points were recorded on a Mel-Temp apparatus
1
and are uncorrected. The H and 13C NMR spectra of

L. Wei et al. / Bioorg. Med. Chem. 11 (2003) 5149–5153
5153
Synthesis of compound 3. To a solution of 2 M oxalyl
chloride in methylene chloride (32 mL; 61 mmol) cooled
to ꢀ78 ꢂC under nitrogen was added dropwise a solu-
tion of dry dimethyl sulfoxide (6.8mL; 90 mmol) in dry
methylene chloride (50 mL) over 5 min. After the mix-
ture was stirred for 0.5 h, a solution of Cbz-l-Val-l-
prolinol (14 g; 42 mmol) in dry methylene chloride
(100 mL) was added dropwise. After stirring for 40 min,
dry triethylamine (13.00 g; 128mmol) in dry methylene
chloride (50 mL) was added to the reaction mixture and
stirring continued for 15 min. Glacial acetic acid (8.20 g;
139 mmol) was added, followed by sodium (triacetoxy)
borohydride (14.0 g; 59 mmol) and compound 2. The
reaction mixture was stirred for 4 h and then neutralized
by adding dropwise cold 10% aq NaOH (pH ꢃ10). The
organic phase was separated and the aqueous phase was
extracted with ethyl acetate (3 ꢁ 300 mL). Removal of
the solvent left a crude product which was purified by
flash chromatography (silica gel/hexane/ethyl acetate)
2-phenylethylamine (0.24 g; 2 mmol) was added and the
solution stirred for 15 min. A solution of DBU (0.30 g;
2 mmol) in dry THF (8mL) was added dropwise and the
reaction mixture stirred for 2 h. The solvent was
removed and the residue was dissolved in ethyl acetate
(30 mL) and washed with 5% NaHCO3 (10 mL), 5%
HCl (10 mL), and brine (10 mL). The organic phase was
dried and then evaporated to give a crude product
which was purified using flash chromatography (silica
gel/hexane/ethyl acetate gradient) to yield a white foam
(0.75 g; 75% yield).
Acknowledgements
Financial support of this work by the National Insti-
tutes of Health (HL57788) and Supergen, Inc. is grate-
fully acknowledged.
1
to yield a light-yellow oil (12.7 g; 58% yield). H NMR
d 0.84–1.02 (m, 12H), 1.30–1.43 (m, 1H), 1.44–1.60 (m,
1H), 1.60–1.68(m, 1H), 1.91–2.02 (m, 6H), 2.42–2.55
(m,1H), 2.76–2.85 (m, 1H), 3.06–3.16 (m, 1H), 3.44–3.56
(m, 1H), 3.73–3.78(s, 3H), 3.83–3.95 (dd, 1H), 4.12–
4.24 (dd, 1H), 4.25–4.38(t 1H), 5.10–5.13 (s, 2H), 5.46–
5.64 (m, 1H), 7.25–7.42 (m, 5H), 7.72–8.86 (br m, 1H).
References and Notes
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Synthesis of compound 4. A mixture of 3 (11.70 g;
22.5 mmol) and 37% aq formaldehyde (24 mL) was
refluxed for 0.5 h. The reaction mixture was allowed to
cool to room temperature and then extracted with
methylene chloride (3 ꢁ 75 mL). The organic phase was
dried over anhydrous sodium sulfate and the solvent
removed in vacuo to yield a pure product (12.01 g;
1
100% yield). H NMR (CDCl3) d 0.82–1.03 (m, 12H),
1.33–1.45 (m, 1H), 1.46–1.60 (m, 1H), 1.68–2.03 (m,
6H), 2.42–2.54 (m, 1H), 2.74–2.86 (m, 1H), 3.14–3.24 (t,
1H), 3.33–3.40 (d, 2H), 3.40–3.50 (m, 1H), 3.64–3.76 (s,
3H), 3.84–3.91 (d, 1H), 3.96–4.08 (m, 1H), 4.24–4.35 (m,
2H), 4.54–4.57 (d, 1H), 5.05–5.14 (d, 1H), 5.61–5.71 (d,
1H), 7.23–7.38(m, 5H).
7. Kuang, R.; Epp, J. B.; Ruan, S.; Yu, H.; Huang, P.; He, S.;
Tu, J.; Schechter, N. M.; Turbov, J.; Froelich, C. J.; Groutas,
W. C. J. Am. Chem. Soc. 1999, 121, 8128.
8. Groutas, W. C.; Kuang, R.; Venkataraman, R.; Epp, J. B.;
Ruan, S.; Prakash, O. Biochemistry 1997, 36, 4739.
9. Dixon, M. Biochem. J. 1953, 55, 170.
10. Schechter, I.; Berger, A. J. Biol. Chem. 1962, 12, 2940.
11. Ohbayashi, H. Expert Opin. Investig. Drugs 2002, 11, 965.
12. Zeiher, B. G.; Matsuoka, S.; Kawabata, K.; Repine, J. E.
Crit. Care Med. 2002, 30, S281.
13. Shamanian, P.; Pocock, B. J. Z.; Schwartz, J. D.; Monea,
S.; Chuang, N.; Whiting, D.; Marcus, S. G.; Galloway, A. C.;
Mignatti, P. Surgery 2000, 126, 142.
14. Fockens, J. A.; Ries, C.; Look, M. P.; Gippner-Steppert,
C.; Klijn, J. G.; Jochum, M. Cancer Res. 2003, 63, 337.
15. Bode, W.; Meyer, E.; Powers, J. C. Biochemistry 1989, 28,
1951.
16. Metz, W. A.; Peet, N. P. Exp. Opin. Ther. Pat. 1999, 9,
851.
Synthesis of compound 5. A solution of 4 (12.01 g;
22.6 mmol) in dioxane (96 mL) was treated with a solu-
tion of potassium hydroxide (15.0 g; 240 mmol) in water
(50 mL). The reaction mixture was stirred at room tem-
perature overnight and then acidified with cold 10%
HCl and the mixture extracted with ethyl acetate (3 ꢁ
250 mL). The organic phase was dried over anhydrous
sodium sulfate and the solvent removed to yield the
product as a light-yellow hygroscopic foam (11.01 g;
94% yield).
17. Anderson, G. P.; Shinagawa, K. Curr. Opin. Anti-inflamm.
Immunom. Invest. Drugs 1999, 1, 29.
18. Related work with cyclic sulfamide derivatives: Zhong, J.;
Gan, X.; Alliston, K. R.; Groutas, W. C. Manuscript in
preparation.
Synthesis of compound 11. A solution of 5 (1.00 g;
2 mmol) in dry THF (5 mL) was added dropwise to a
solution of 1,10-carbonyl diimidazole (0.34 g; 2 mmol) in
dry THF (5 mL). After the mixture was stirred for 0.5 h,