Synthesis, resolution, and determination of the absolute configuration of the enantiomers of cis-4,5-dihydroxy-1,2-dithiane 1,1-dioxide, an HIV-1 NCp7 inhibitor

Article abstract of DOI:10.1016/S0968-0896(03)00269-4

The anti-HIV activity of (±)-cis-4,5-dihydroxy-1,2-dithiane 1,1-dioxide [(±)-cis-1,1-dioxo-[1,2]-dithiane-4,5-diol, NSC-624151] and its attack on the zinc finger domain of the HIV-1 nucleocapsid p7 (NCp7) protein has been established [Rice, W. G.; Baker, D. C.; Schaeffer, C. A.; Graham, L.; Bu, M.; Terpening, S.; Clanton, D.; Schultz, R.; Bader, J. P.; Buckheit, R. W.; Field, L.; Singh, P. K. Turpin, J. A. Antimicrob. Agents Chemother. 1997, 41, 419]. In order to determine which enantiomer of NSC-624151 is the more active component, the compound was resolved via its bis-'Mosher ester', which was prepared via its reaction with two equiv of (-)-(R)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride. The diastereoisomeric esters were separated, and each ester was hydrolyzed to yield enantiomers with [α]_D²¹ +151° (c 0.5, MeOH) and [α]_D²¹ -146° (c 0.5, MeOH). Single-crystal X-ray analysis of the (-)-bis-'Mosher ester' showed that the (-)-enantiomer is the (4S, 5R)-compound. The (-)-enantiomer (NSC 693195) was ca. twice as active (EC₅₀ 8.8±0.2 μM) as its (+)-counterpart (NSC 693194) (EC₅₀ 16.2±2.4 μM) in the XTT assay against HIV-1. All three compounds were found to be approximately equally effective in promoting Zn ejection from the NCp7 zinc finger. As the more anti-HIV active enantiomer is only slightly more active than the racemic form, it appears to offer no advantages over the racemic form.

Full text of DOI:10.1016/S0968-0896(03)00269-4

Bioorganic & Medicinal Chemistry 11 (2003) 3215–3219
Synthesis, Resolution, and Determination of the Absolute
Configuration of the Enantiomers of cis-4,5-dihydroxy-
1,2-dithiane 1,1-dioxide, an HIV-1 NCp7 Inhibitor
Anand Mayasundari,a,y William G. Rice,b,{
Jonathan B. Diminniea,x and David C. Bakera,*
aDepartment of Chemistry, The University of Tennessee, Knoxville, Knoxville, TN 37996-1600, USA
bLaboratory of Antiviral Drug Mechanisms, National Cancer Institute-FCRDC, SAIC Frederick,
Frederick, MD 21702-1201, USA
Received 19October 2002; accepted 20 March 2003
Abstract—The anti-HIV activity of (Æ)-cis-4,5-dihydroxy-1,2-dithiane 1,1-dioxide [(Æ)-cis-1,1-dioxo-[1,2]-dithiane-4,5-diol,
NSC-624151] and its attack on the zinc finger domain of the HIV-1 nucleocapsid p7 (NCp7) protein has been established [Rice, W.
G.; Baker, D. C.; Schaeffer, C. A.; Graham, L.; Bu, M.; Terpening, S.; Clanton, D.; Schultz, R.; Bader, J. P.; Buckheit, R. W.;
Field, L.; Singh, P. K. Turpin, J. A. Antimicrob. Agents Chemother. 1997, 41, 419]. In order to determine which enantiomer of
NSC-624151 is the more active component, the compound was resolved via its bis-‘Mosher ester’, which was prepared via its
reaction with two equiv of (À)-(R)-a-methoxy-a-(trifluoromethyl)phenylacetyl chloride. The diastereoisomeric esters were sepa-
21
D
21
D
rated, and each ester was hydrolyzed to yield enantiomers with ½ꢀŠ +151ꢀ (c 0.5, MeOH) and ½ꢀŠ À146ꢀ (c 0.5, MeOH). Single-
crystal X-ray analysis of the (À)-bis-‘Mosher ester’ showed that the (À)-enantiomer is the (4S, 5R)-compound. The (À)-enantiomer
(NSC 693195) was ca. twice as active (EC50 8.8Æ0.2 mM) as its (+)-counterpart (NSC 693194) (EC50 16.2Æ2.4 mM) in the XTT
assay against HIV-1. All three compounds were found to be approximately equally effective in promoting Zn ejection from the
NCp7 zinc finger. As the more anti-HIV active enantiomer is only slightly more active than the racemic form, it appears to offer no
advantages over the racemic form.
# 2003 Elsevier Science Ltd. All rights reserved.
Introduction
protease,5À7 and drugs are under development that target
the viral integrase8À11 or the viral gp120 glycoprotein.12
Because these drugs ultimately suffer from cross-resis-
tance within drug classes and the development of resis-
tance to new drug entities,4,13 it is highly desirable to
create new drug classes that target atypical viral struc-
tures, especially those that are highly conserved, and,
hence, resistant to mutation.
It is well established that the human immunodeficiency
virus type 1 (HIV-1) has an extreme tendency to mutate
to forms that are resistant to existing antiviral thera-
pies.1 The most common approach to combating the
rapid emergence of drug-resistant HIV is to treat infec-
ted individuals with a cocktail of drugs that simulta-
neously disrupt virus replication through multiple
modalities.2À4 Such cocktails include the combination of
drugs that target the viral reverse transcriptase or
For some time it has been recognized that in all lenti-
and oncoretroviruses, the nucleocapsid (NC) proteins
contain one or two highly conserved Cys-Xaa2-Cys-
Xaa4-His-Xaa4-Cys (CCHC, where Xaa is any amino
acid) peptide segments14,15 that are coordinated to zinc
and are known as retroviral zinc fingers.16,17 The spa-
cing and the zinc-chelating residues (three Cys and one
His) of the zinc finger motif are absolutely conserved,
and mutations in the metal-chelating residues lead to a
noninfectious virus.18À20 The zinc finger domains within
the Pr55gag and Pr160gag-pol precursor polyproteins are
*Corresponding author. Tel.: +1-865-974-3395; fax: +1-865-974-
1536; e-mail: dcbaker@utk.edu
yPresent address: Department of Biochemistry and Cellular and
Molecular Biology, The University of Tennessee, Knoxville, TN
37996-0840, USA.
{Present address: Achillion Pharmaceuticals, 300 George Street, New
Haven, CT 06511, USA.
xPresent address: Olin Chlor-Alkali Products, 1186 Lower River
Road, NW, Charleston, TN 37310-0248, USA.
0968-0896/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0968-0896(03)00269-4

3216
A. Mayasundari et al. / Bioorg. Med. Chem. 11 (2003) 3215–3219
involved in a number of essential viral processes includ-
ing reverse transcription,21,22 integration,23 protease
processing,24 and packaging of viral RNA.18 The mature
NCp7 protein results from the processing of these pre-
cursor polyproteins,25 and the zinc fingers of this protein
are needed to initiate further infection.21,26À28 Hence,
compounds that attack the retroviral zinc finger may
function as inhibitors in more than one step of the HIV-1
replication cycle and may provide an improved approach
to anti-HIV chemotherapy.29À31
chloride and DMAP in dry CH2Cl2 into its ‘Mosher
esters’ 2 and 3.47,48 Diastereomers (+)-2 and (À)-3 were
then separated on a silica gel column and subsequently
hydrolyzed to the diols (+)-4 and (À)-5, respectively,
with 40% NH3 in MeOH. Then, in order to determine
the absolute stereochemistry at C-4 and C-5, a single-
crystal X-ray structure of compound (À)-3 was
obtained, which indicated the (À)-enantiomer (À)-5 to
be the (4S, 5R) compound, based on apparent relative
configurations of the stereogenic centers with the known
chirality of the ester ligands. Details of the X-ray struc-
tural determination are in Table 1, and the ORTEP
structure of (À)-3 is shown in Figure 1.
It has been shown that within the HIV-1 nucleocapsid p7
protein, the sulfur atoms of the Cys residues that are
coordinated to zinc can be covalently modified through
electrophilic attack by various functional groups.32
Among active compounds are aromatic C-nitroso com-
pounds,33,34 2,20-dithiobisbenzamides and derivatives,35,36
cyclic 2,20-dithiobisbenzamides,37,38 pyridinioalkanoyl
esters and thioesters,39À41 and thiolcarbamates.42
Anti-HIV-1 activity
Evaluation of the enantiomers (+)-4 and (À)-5 in the
XTT-based cytoprotection assay revealed slightly more
Table 1. Crystal structure data for compound (À)-3
The NCI’s XTT-based cytoprotection assay for anti-
HIV compounds43 had identified cis- and trans-4,5-
dihydroxy-1,2-dithiane 1,1-dioxide44 as inhibitors of
HIV-1 replication. Our extension of this research was to
determine which enantiomer of the more potent cis
compound (Æ1) was responsible for the anti-HIV
activity through interaction with NCp7.
Empirical formula
Formula weight
Temperature
C24H22F6O8S2
616.54
293(2) K
Wavelength
0.71073 A
Crystal system
Space group
Unit cell dimensions
Orthorhombic
P212121 (no. 19)
a=7.536(3) A
b=12.886(5) A
c=27.470(11) A
2668(2) A3, 4
1.535 mg/m3
0.288 mmÀ1
1264
a=90ꢀ
b=90ꢀ
g=90ꢀ
Volume, Z
Density (calculated)
Absorption coefficient
F(000)
Results and Discussion
Resolution of (Æ)-cis-4,5-dihydroxy-1,2-dithiane 1,1-di-
oxide [(Æ)-1] (Scheme 1)
Crystal size
ꢀ range for data collection
Limiting indices
0.30 Â 0.22 Â 0.20 mm
2.17 to 22.58ꢀ
0ꢁh ꢁ8, 0ꢁk ꢁ13, À29ꢁl ꢁ29
4158
3443 (Rint=0.1354)
Full-matrix least-squares on F2
3440/0/361
Previous studies using the XTT-based cytoprotection
assay45 had identified (Æ)-cis-4,5-dihydroxy-1,2-
dithiane 1,1-dioxide (Æ-1)44 as the more potent of the
two (cis–trans) stereoisomers. In order to determine
which enantiomer of the cis isomer is the more active
anti-HIV agent, resolution was attempted by a number
of methods, including the use of lipases and hydrolases
on appropriate ester derivatives, as well as separation of
the bis-benzoyl derivative of (Æ)-1 on a chiral d-phen-
ylglycine HPLC column (data not shown). Neither
method proved successful.46 Conversion of (Æ)-1 to a
set of diesters with an optically active acyating agent
and separation of the resulting diastereomers was the
next option. Thus (Æ)-1 was converted by reaction with
(À)-(R)-a-methoxy-a-(trifluoromethyl)phenylacetyl
Reflections collected
Independent reflections
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I >2s(I)]
R indices (all data)
Absolute structure parameter
Largest diff. peak and hole
1.108
R1=0.0857, wR2=0.1324
R1=0.2059, wR2=0.1865
0.0(3)
0.308 and À0.289eA À3
Figure 1. ORTEP view of bis-Mosher ester (À)-3 shown as 50% ther-
Scheme. 1. Resolution of (Æ)-1 into its enantiomers 4 and 5.
mal ellipsoids.

A. Mayasundari et al. / Bioorg. Med. Chem. 11 (2003) 3215–3219
3217
potent antiviral activity by the (À)-enantiomer 5
(NSC-693195), which showed an EC50 of 8.8 mM and an
CC50 of 132 mM, compared with an EC50 of 16.2 mM
and an CC50 of 134 mM for the (+)-enantiomer (+)-4
(Table 2). Thus the (À)-enantiomer (À)-5 is almost twice
as active as its (+)-enantiomer, and the CC50 values are
equivalent.
and –OAc analogues in the previous paper.45) These
observations, together with the fact that the anti-HIV
activities of the two enantiomers [(+)-4 and (À)-5] differ
only by a factor of two, would seem to indicate that the
presence of substituents, as well as their stereo-
chemistry, play a more important role in some other
phenomena that are important in determining anti-HIV
activity—drug delivery, compound stability, host-cell
toxicity (as indicated by CC50 values), or possibly other
properties—and that, at least with these compounds,
the interaction with the zinc finger protein per se is itself
less selective and is a process that has far lower demands
on the finer aspects of the structure of the interacting
species.
Using an assay that measures the ejection of zinc from
the HIV-1 p7 nucleocapsid protein (NCp7) protein,45
these compounds were found to target the highly con-
served retroviral zinc fingers. The assay measures the
decrease in relative fluorescence (reported in relative
fluorescence units, RFU) following the loss of zinc from
the C-terminal zinc finger. The loss of fluorescence
occurs as the Trp37 residue folds away from the aqueous
environment. The greater the percent decrease of RFU,
which is measured at time intervals of 0, 3, 10 and
30 min, the better is the ability of the compound to eject
zinc from the zinc finger. The results (Table 2) show that
all three compounds, the (Æ)-1, (+)-4, and (À)-5, show
approximately equivalent rates of zinc ejection in the
assay.
Single-crystal X-ray structure of (À)-3
The X-ray crystal structure of (À)-3 was determined at
20 ꢀC on a Siemens R3m/V diffractometer. A suitable
crystal was mounted using epoxy on a glass fiber. Unit
cell dimensions were calculated from the angular setting
of 35 well-centered reflections having 2ꢁ values in the
range of 15–25ꢀ. Compound (À)-3 was found to crys-
tallize in the orthorhombic system. Axial dimensions
were confirmed by use of axial photographs. Two
unique octants of data were collected for a total of 4158
(3443 unique) reflections. Corrections for Lorentz and
polarization effects were applied during data reduction;
absorption effects were ignored (m=0.288 mmÀ1). The
jEÃE À 1j statistics, as well as observed systematic
absences, were uniquely consistent with the space group
P212121. The structure was solved by direct methods
using the Siemens SHELXTL-93 (Version 5.0) proprie-
tary software package, and refined by Full-Matrix Least
Squares on F2 until the structure converged to R
(RwF2)=8.57% (13.24%). All non-hydrogen atoms
were anisotropically refined. Hydrogen atoms were
placed at calculated positions and introduced into the
refinement as fixed contributors with an isotropic U
value of 0.08 A2. The ORTEP view of bis-Mosher ester
(À)-3 as 50% thermal ellipsoids is shown in Figure 1
and its crystal structure data are given in Table 1.50
While no studies to determine the precise mode of
action for these compounds have been undertaken, their
behavior in the NCp7 zinc ejection assay indicates that
they are likely substrates for a nucleophilic reaction
with specific Cys residues of the zinc fingers in a step-
wise fashion similar to that established for pyr-
idinioalkanoyl esters.40 The chemical reaction would be
similar to that established for the decomposition in base
of these cyclic 1,2-dithiane 1,1-dioxides as reported by
Field and co-workers44 or that accepted for the hydro-
lysis of cyclic thiosulfonates in general.49 It is interesting
to note that, while OH substitution at C-4 and C-5, as
well as the cis or trans configuration of the –OH sub-
stituents, are important in determining anti-HIV activ-
ity as determined in the XTT-based cytoprotection
assay (–OAc or –H substitution renders the compounds
essentially inactive),45 neither the presence of, nor the
relative configurations of, these substituents has much
effect on the rate of ejection of zinc in the Trp37 assay.
(See data in Table 2 as well as that reported for the –OH
Experimental
Table 2. XTT Cytoprotection assay and NCp7 zinc ejection assay for
compounds (Æ)-1, (+)-4, and (À)-5
General procedures (chemistry)
Compda
XTT Assayb
NCp7 Trp37Assay (RFU)c
Melting points were determined on a Thomas–Hoover
capillary melting point apparatus and are uncorrected.
Analytical TLC was performed on aluminum-backed
plates coated with E. Merck Silica Gel-60 F-254. The
developed plates were air-dried and visualized by irra-
diation with UV light and/or by dipping in 10 wt%
phosphomolybdic acid solution in ethanol, followed by
heating at 120–140 ꢀC. Flash column chromatography
was performed on Silica Gel-60 (230–400 mesh). The
HPLC analysis was carried out on a Beckman System
Gold instrument using a Regis no. 731221 Pirkle
d-phenylglycine (25 cm  1 cm i.d.) column. Optical
rotations were measured with a Perkin–Elmer Model
243 automatic polarimeter for solutions in a 1-dm cell at
EC50 (mM) CC50 (mM)
0
3
10
30 min
(Æ)-1
(+)-4
(À)-5
12.2Æ2.7
16.2Æ2.4
8.8Æ0.2
122Æ5
134Æ1
132Æ3
295
280
136
146
75
75
42
41
279117
69 45
aThe National Cancer Institute’s NSC numbers are as follows: (Æ)-1,
NSC-624151; (+)-4, À693194; (À)-5, À693195.
bThe assay was run according to the protocols previously established
using an XTT-based cytoprotection study with CEM-SS cells and
HIV-1.34,45 EC50, effective concentration for 50% cytoprotection;
CC50, cytotoxic concentration, 50%; that is, compound concentration
to reduce cell viability 50%. The mean values of duplicate runs are
reported.
cThe NCp7 activity assay was conducted as previously described using
NCp7 protein and monitoring of the ejection of Zn2+ by the fluores-
cence of Newport Green following the chelation of Zn2+ 40
1
the indicated temperature. H and 13C NMR spectra
.

3218
A. Mayasundari et al. / Bioorg. Med. Chem. 11 (2003) 3215–3219
were recorded at 250 and 62.9MHz, respectively, on a
Bruker AC 250 instrument using the indicated solvent.
1H NMR shifts are reported as d (ppm) downfield from
tetramethylsilane (TMS), which was used as an internal
standard; multiplicities are first-order values in Hz: s,
singlet; bs, broad singlet; d, doublet; t, triplet; dd, dou-
ble of doublets; db, broad doublet; q, quartet; m, mul-
tiplet. 13C NMR chemical shifts are reported as d (ppm)
relative to the chemical shift of the solvent used (CDCl3:
77.0 ppm; CD3OD: 49.0 ppm). Elemental analyses were
performed by Atlantic Microlabs, Inc. of Atlanta, GA,
USA. Chemicals were of reagent grade and were used
directly. Solvents were distilled and dried by literature
procedures before use. All evaporations were carried
out with a rotary evaporator under vacuum and below
40 ꢀC.
The reaction mixture was then concentrated under
vacuum, and the crude oil was purified by silica gel
chromatography using 95:5 CH2Cl2–MeOH as the elu-
ent to give (+)-4 (0.0212 g, 43%) as a white solid: mp
21
D
133–134 ꢀC; ½aŠ +151ꢀ (c 0.5, CD3OD); 1H NMR
(CD3OD): d 4.20 (m, 1H), 4.13 (m, 1H), 3.66 (dd, 1H,
J=12.6 Hz, J=11.0 Hz), 3.47 (dd, 1H, J=14.7 Hz,
J=1.4 Hz), 3.37 (m, 2H); 13C NMR (CD3OD) d 71.44,
65.92, 61.62, 38.63. Anal. calcd for C4H8O4S2: C, 27.74;
H, 4.66; S, 32.77. Found: C, 27.75; H, 4.58; S, 32.57.
(À)-cis-4,5-Dihydroxy-1,2-dithiane 1,1-dioxide [(À)-5].
As for (+)-2, compound (À)-3 (0.159g, 0.258 mmol)
was deacylated and purified to give (À)-5 (0.019g, 40%)
21
D
as a white solid: mp 131–132 ꢀC; ½aŠ À146ꢀ (c 0.5,
1
CD3OD); H NMR (CD3OD): d 4.19(m, 1H), 4.13 (m,
1H), 3.66 (dd, 1H, J=12.8 Hz, J=10.9Hz), 3.47 (dd,
1H, J=14.7 Hz, J=1.5 Hz), 3.37 (m, 2H); 13C NMR
(CD3OD) d 71.42, 65.91, 61.62, 38.63. Anal. calcd for
C4H8O4S2 0.14C4H8O2: C, 27.86; H, 4.68; S, 32.62.
Found: C, 27.85; H, 4.59; S, 32.44.
(2S,4R,5S)-(+)-3,3,3-Trifluoro-2-methoxy-2-phenylpro-
pionic acid 1,1-dioxo-4-[(2S)-3,3,3-trifluoro-2-methoxy-
2-phenylpropionyloxy][1,2]dithiane-5-yl ester [(+)-2] and
(2S,4S,5R)-(À)-3,3,3-trifluoro-2-methoxy-2-phenylpro-
pionic acid 1,1-dioxo-4-[(2S)-2-methoxy-2-phenyl-3,3,3-
trifluoropropionyloxy][1,2]dithiane-5-yl ester [(À)-3]. To
(Æ)-1 (0.225 g, 1.22 mmol) and N,N-dimethylaminopyr-
idine (0.597 g, 4.89 mmol) in dry CH2Cl2 (5 mL) was added
(À)-(R)-a-methoxy-a-(trifluoromethyl)phenylacetyl chlo-
ride (0.750 g, 2.97 mmol) over 30 min at 0 ꢀC under N2.
The reaction mixture was allowed to gradually rise to
room temperature and stir at that temperature for 20 h.
Then, the reaction mixture was cooled in an ice bath,
washed with N HCl, followed by satd aq NaHCO3, and
finally with dist H2O. The CH2Cl2 layer was dried with
anhyd Na2SO4 and concentrated, and the crude product
was purified on a column of silica gel with 85:15 hex-
.
Antiviral activity determinations
The antiviral activities were determined in an XTT [2,3-
bis[2-methoxy-4-nitro-5-sulfophenyl]-5-[(phenylamino)-
carbonyl]-2H-tetrazolium hydroxide]-based cytoprotec-
tion assay using CEM-SS cells and HIV-1 as previously
described.34,45 Details of the results are in Table 2.
Acknowledgements
This work was supported, in part, by Contract No.
N01-CM-47038 (to D.C.B.) from the Drug Synthesis
and Chemistry Branch of the National Cancer Institute.
anes–EtOAc to obtain (+)-2 (0.252 g, 34%) as the 1st
21
fraction; mp: 162–163 ꢀC: ½aŠ +81ꢀ (c 1.0, CH2Cl2);
D
1H NMR (CDCl3): d 7.39(m, 10H), 5.79(m, 1H), 5.59
(m, 1H), 3.67 (m, 3H), 3.49(s, 3H), 3.40 (dd, 1H,
J=15.5 Hz, J=5.1 Hz), 3.25 (s, 3H); 13C NMR (CDCl3)
d 165.35, 165.19, 131.29, 131.14, 130.10, 129.95, 128.77,
128.61, 126.91, 125.16, 120.59, 116.02, 85.40, 84.94,
84.44, 84.01, 70.78, 65.73, 58.47, 55.52, 55.38, 34.15.
Anal. calcd for C24H22F6O8S2: C, 46.75; H, 3.60; S,
10.40. Found: C, 46.79; H, 3.58; S, 10.29. The 2nd
fraction yielded diastereomer (À)-3 (0.250 g, 33%) as
References and Notes
1. Coffin, J. M. Science 1995, 267, 483.
2. Battegay, M. Expert Opin. Invest. Drugs 2001, 10, 175.
3. Temesgen, Z. Expert Opin. Pharmacother. 2001, 2, 1239.
4. O’Brien, T. R.; Engels, E. A. Infect. Disease and Ther. 2002,
27, 163.
5. Ren, S.; Lien, E. J. Antiviral Agents 2001, 1.
6. Erickson, J. W. Infect. Disease and Ther. 2002, 25, 1.
7. Murata, H.; Hruz, P. W.; Mueckler, M. Curr. Drug Tar-
gets: Infect. Disorders 2002, 2, 1.
8. Neamati, N.; Marchand, C.; Winslow, H. E.; Pommier, Y.
Antiretroviral Ther. 2001, 87.
9. Sayasith, K.; Sauve, G.; Yelle, J. Expert Opin. Ther. Tar-
gets 2001, 5, 443.
10. Pluymers, W.; De Clercq, E.; Debyser, Z. Curr. Drug
Targets: Infect. Disorders 2001, 1, 133.
11. Tarrago-Litvak, L.; Andreola, M. L.; Fournier, M.;
Nevinsky, G. A.; Parissi, V.; de Soultrait, V. R.; Litvak, S.
Curr. Pharm. Design 2002, 8, 595.
white crystals: mp: 184–185 ꢀC (from hexanes–EtOAc);
21
D
½ꢀŠ À120ꢀ (c 1.0, CH2Cl2); H NMR (CDCl3): d 7.38
1
(m, 10H), 5.76 (m, 2H), 3.73 (d, 1H, J=15.4 Hz), 3.54
(m, 3H), 3.45 (s, 3H), 3.40 (s, 3H); 13C NMR (CDCl3) d
165.41, 165.31, 131.17, 131.07, 130.07,130.01, 128.73,
128.65, 127.31, 126.96, 125.27, 125.18, 120.67, 120.58,
116.09, 115.97, 85.38, 84.93, 84.48, 84.03, 70.84, 66.28,
58.36, 55.58, 55.32, 34.47. Anal. calcd for
C24H22F6O8S2: C, 46.75; H, 3.60; S, 10.40. Found: C,
46.68; H, 3.66; S, 10.32. For single-crystal X-ray data,
see Table 1 and Figure 1.
12. Redshaw, S.; Westby, M. Expert Opin. Emerging Drugs
2001, 6, 209.
13. Mellors, J. W.; Larder, B. A.; Schinazi, R. F. Int. Antiviral
News 1995, 3, 8.
14. Berg, J. M. Science 1986, 232, 485.
(+)-cis-4,5-Dihydroxy-1,2-dithiane 1,1-dioxide [(+)-4].
To (+)-2 (0.167 g, 0.271 mmol) was added 40% NH3 in
MeOH (4 mL) over 5 min under N2 at room temperature.
The solid went into solution as 40% NH3 in MeOH was
added, and the solution turned pale yellow in color. After
1.5 h, TLC showed complete disappearance of the diester.
15. Green, L. M.; Berg, J. M. Proc. Natl. Acad. Sci. U.S.A.
1989, 86, 4047.

A. Mayasundari et al. / Bioorg. Med. Chem. 11 (2003) 3215–3219
3219
16. Berg, J. M.; Shi, Y. Science 1996, 271, 1081.
17. Ramboarina, S.; Morellet, N.; Fournie-Zaluski, M.-C.;
Roques, B. P. Biochemistry 1999, 38, 9600.
18. Aldovini, A.; Young, R. A. J. Virol. 1990, 64, 1920.
19. Dorfman, T.; Luban, J.; Goff, S. P.; Haseltine, W. A.;
Gottlinger, H. G. J. Virol. 1993, 67, 6159.
20. Krausslich, H. G.; Facke, M.; Heuser, A. M.; Konvalinka,
J.; Zentgraf, H. J. Virol. 1995, 69, 3407.
21. Darlix, J. L.; Vincent, A.; Gabus, C.; de Rocquigny, H.;
Roques, B. C. R. Acad. Sci. III 1993, 316, 763.
22. Li, X.; Quan, Y.; Arts, E. J.; Preston, B. D.; De Roc-
quigny, H.; Roques, B. P.; Darlix, J.-L.; Klieman, L.; Parniak,
M. A.; Wainberg, M. A. J. Virol. 1996, 70, 4996.
23. Carteau, S.; Batson, S. C.; Poljak, L.; Mouscadet, J. F.; de
Rocquigny, H.; Darlix, J.-L.; Roques, B. P.; Kas, E.; Auclair,
C. J. Virol. 1997, 71, 6225.
24. Zybarth, G.; Carter, C. J. Virol. 1995, 69, 3878.
25. Henderson, L. E.; Bowers, M. A.; Sowder, R. C.; Serabyn,
S. A.; Johnson, D. G.; Bess, J. W.; Arthur, L. O.; Bryant,
D. K.; Fenselau, C. J. Virol. 1992, 66, 1856.
26. Demene, H.; Dong, C. Z.; Ottmann, M.; Rouyez, M. C.;
Jullian, N.; Morellet, N.; Mely, Y.; Darlix, J. L.; Fournie-
Zaluski, M. C.; Saragosti, S.; Roques, B. P. Biochemistry 1994,
33, 11707.
27. Seligmann, M.; Warrell, D. A.; Aboulker, J. P.; Carbon,
C.; Darysshire, J. H.; Dormot, J.; Eschwege, E.; Girling, D. J.;
James, D. R.; Levy, J. P.; Peto, T. E. A.; Schwartz, D.; Stone,
A. B.; Weller, I. V. D.; Withnall, R. Lancet 1994, 343, 871.
28. Tanchou, V.; Gabus, C.; Rogemond, V.; Darlix, J. L.
J. Mol. Biol. 1995, 252, 563.
29. Rice, W. G.; Turpin, J. A. Rev. Med. Virol. 1996, 6, 187.
30. Rein, A. Rec. Res. Develop. Virol. 1999, 1, 849.
31. Druillennec, S.; Roques, B. P. Drug News Perspect. 2000,
13, 337.
J.; Gogliotti, R.; Sanchez, J.; Song, Y.; Hupe, D. Antimicrob.
Agents Chemother. 1997, 41, 394.
37. Turpin, J. A.; Schaeffer, C. A.; Terpening, S. J.; Graham,
L.; Bu, M.; Rice, W. G. Antiviral Chem. Chemother. 1997, 8,
60.
38. Witvrouw, M.; Balzarini, J.; Pannecouque, C.; Jhaumeer-
Laulloo, S.; Este, J. A.; Schols, D.; Cherepanov, P.; Schmit, J.-C.;
Debyser, Z.; Vandamme, A.-M.; Desmyter, J.; Ramadas, S. R.;
De Clercq, E. Antimicrob. Agents Chemother. 1997, 41, 262.
39. Huang, M.; Maynard, A.; Turpin, J. A.; Graham, L.;
Janini, G. M.; Covell, D. G.; Rice, W. G. J. Med. Chem. 1998,
41, 1371.
40. Basrur, V.; Song, Y.; Mazur, S. J.; Higashimoto, Y.; Tur-
pin, J. A.; Rice, W. G.; Inman, J. K.; Appella, E. J. Biol.
Chem. 2000, 275, 14890.
41. Song, Y.; Goel, A.; Basrur, V.; Roberts, P. E. A.; Miko-
vits, J. A.; Inman, J. K.; Turpin, J. A.; Rice, W. G.; Appella,
E. Bioorg. Med. Chem. 2002, 10, 1263.
42. Goel, A.; Mazur, S. J.; Fattah, R. J.; Hartman, T. L.;
Turpin, J. A.; Huang, M.; Rice, W. G.; Appella, E.; Innman,
J. K. Bioorg. Med. Chem. Lett. 2002, 12, 767.
43. Buckheit, R. W., Jr.; Hollingshead, M. G.; Germany-
Decker, J.; White, E. L.; McMahon, J. B.; Allen, L. B.; Ross,
L. J.; Decker, W. D.; Westbrook, L.; Shannon, W. M.; Wei-
slow, O.; Bader, J. P.; Boyd, M. R. Antiviral Res. 1993, 21, 247.
44. Singh, P. K.; Nguyen, T. Q.; Field, L.; Sweetman, B. J.
Sulfur Lett. 1988, 8, 107.
45. Rice, W. G.; Baker, D. C.; Schaeffer, C. A.; Graham, L.;
Bu, M.; Terpening, S.; Clanton, D.; Schultz, R.; Bader, J. P.;
Buckheit, R. W.; Field, L.; Singh, P. K.; Turpin, J. A. Anti-
microb. Agents Chemother. 1997, 41, 419.
46. Mayasundari, A. Synthetic and Structural Studies on Anti-
HIV Agents; PhD. Dissertation; The University of Tennessee:
Knoxville, TN, 1998.
32. Scozzafava, A.; Mastrolorenzo, A.; Supuran, C. T. Expert
Opin. Ther. Pat. 2001, 11, 765 and references cited therein.
33. Rice, W. G.; Schaeffer, C. A.; Harten, B.; Villinger, F.;
South, T. L.; Summers, M. F.; Henderson, L. E.; Bess, J. W.;
Arthur, L. O.; McDougal, J. S.; Orloff, S. L.; Mendeleyev, J.;
Kun, E. Nature 1993, 361, 473.
47. Dale, J. A.; Dull, D. L.; Mosher, H. S. J. Org. Chem.
1969, 34, 2543.
48. Niwa, H.; Ogawa, T.; Okamoto, O.; Yamada, K. Tetra-
hedron 1992, 48, 10531.
49. Laleh, A.; Ranson, R.; Tillett, J. G. J. Chem. Soc., Perkin
Trans. 2 1980, 610.
34. Rice, W. G.; Schaeffer, C. A.; Graham, L.; Bu, M.;
McDougal, J. S.; Orloff, S. L.; Villinger, F.; Young, M.;
Oroszlan, S.; Fesen, M. R.; Pommier, Y.; Mendeleyev, J.;
Kun, E. Proc. Natl. Acad. Sci. U.S.A. 1993, 90, 9721.
35. Loo, J. A.; Holler, T. P.; Sanchez, J.; Gogliotti, R.; Mal-
oney, L.; Reily, M. D. J. Med. Chem. 1996, 39, 4313.
36. Tummino, P. J.; Harvey, P. J.; McQuade, T.; Domagala,
50. The crystal structure data have been deposited with
the Cambridge Crystallographic Data Centre. These data
may be obtained upon request from The Directory,
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK. Fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk; WEB: http://www.ccdc.cam.ac.uk.
Deposition number: 200053.