Flexible enantiodivergent synthesis and biological activity of mannostatin analogues, new cyclitol glycosidase inhibitors

Article abstract of DOI:10.1021/jo951126v

Mannostatin A (1) is a new cyclitol inhibitor of glycoprotein processing. 2-Epimannostatin A (12) and its enantiomer (13) as well as their positional isomers (14, 15) were designed for probing structure-activity relationships in this class of glycosidase inhibitors. The analogues have been synthesized from (S)-4-((tert-butyldimethylsilyl)oxy)-2-cyclopentenone by an enantiodivergent strategy in a totally stereospecific fashion. Compound 13 showed inhibition against almond β-glucosidase and is shown to be a topographical analogue of β-D-glucopyranoside.

Full text of DOI:10.1021/jo951126v

480
J . Org. Chem. 1996, 61, 480-488
F lexible En a n tiod iver gen t Syn th esis a n d Biologica l Activity of
Ma n n osta tin An a logu es, New Cyclitol Glycosid a se In h ibitor s
Yoshio Nishimura,* Yoji Umezawa, Hayamitsu Adachi, Shinichi Kondo, and Tomio Takeuchi
Institute of Microbial Chemistry, 3-14-23 Kamiosaki, Shinagawa-ku, Tokyo 141, J apan
Received J une 21, 1995X
Mannostatin A (1) is a new cyclitol inhibitor of glycoprotein processing. 2-Epimannostatin A (12)
and its enantiomer (13) as well as their positional isomers (14, 15) were designed for probing
structure-activity relationships in this class of glycosidase inhibitors. The analogues have been
synthesized from (S)-4-((tert-butyldimethylsilyl)oxy)-2-cyclopentenone by an enantiodivergent
strategy in a totally stereospecific fashion. Compound 13 showed inhibition against almond
â-glucosidase and is shown to be a topographical analogue of â-D-glucopyranoside.
Ch a r t 1
In tr od u ction
Oligosaccharides, in the form of glycoproteins, are
involved in a variety of biological functions such as
immune response, oncogenesis, metastasis of tumors, and
viral infection, etc. Specific inhibitors of the glycosidases
involved in the biosynthesis of the oligosaccharide chains
of glycoproteins have been useful in unraveling how
glycosidases catalyze hydrolysis1 and how they produce
beneficial pharmaceutical effects in their roles as anti-
viral,2 antimetastatic,3 antitumor,4 or immunoregulatory
agents.3a,5
sponding glycose, such as nojirimycin,8 galactostatin,9
castanospermine,10 swainsonine,11 and their congeners.12
The structure-activity relationship of 1 is unclear since
the structure of an aminocyclopentanetriol bearing sulfur
has little resemblance either to D-mannose or to the
mannosyl cation 3 (Chart 1), the transition-state inter-
mediate in this enzymatic hydrolysis.13 It is even more
ambiguous that the antipode of 1, rather than 1 itself,
more closely resembles 3.14
Due to its intriguing chemical structure and inhibitory
mechanism, 1 has become an attractive synthetic target,
resulting in four independent syntheses14,15 and an
improved synthesis.16 Several analogues and derivatives
of 1 have also been designed and synthesized for a
mechanistic investigation.17 Our need for specific glu-
cosidase inhibitors arose in connection with projects on
antitumor metastasis and anti-AIDS studies. The ob-
servation that some glucosidase inhibitors show antitu-
mor metastasis3a,e and anti-HIV18 activities prompted us
to rationally design specific glucosidase inhibitors mod-
eled after 1. Here we report a flexible enantiodivergent
synthesis of analogues of 1 that exhibit glucosidase
inhibition.
In 1989, mannostatins A [1, (1R,2R,3R,4S/5R)-4-amino-
5-(methylthio)-1,2,3-cyclopentanetriol] and B (2) were
isolated from the culture filtrate of Streptoverticillium
verticillus var. quintum ME3-AG3 and were shown to be
potent competitive inhibitors of the rat epididymal
R-mannosidase.6 Compound 1 also competitively and
potently inhibited jack bean, mung bean, and rat liver
lysosomal R-mannosidases and proved to be a potent
inhibitor of the Golgi glycoprotein-processing enzyme
mannosidase II but was inactive against the processing
mannosidase I.7 In cell culture, 1 blocked the normal
processing of influenza viral glycoproteins, resulting in
the accumulation of hybrid types of oligosaccharides.7
The structure of 1 is quite distinct from the usual
glycohydrolase inhibitors, which are polyhydroxylated
monocyclic or bicyclic alkaloids resembling the corre-
X Abstract published in Advance ACS Abstracts, J anuary 1, 1996.
(1) Review: Elbein, A. D. In Annual Review of Biochemistry;
Richardson, C. C., Boyer, P. D., Dawid, I. B., Meister, A., Eds.; Annual
Reviews Inc.: California, 1987; Vol. 56, p 497.
(2) (a) Gruters, R. A.; Neefjes, J . J .; Terswette, M.; de Goede, R. E.
Y.; Tulp, A.; Huisman, H. G.; Miedema, F.; Ploegh, H. L. Nature 1987,
330, 74. (b) Walker, B. D.; Kawalski, M.; Goh, W.; Kozarsky, K.;
Kreiger, M.; Rosen, C.; Rohrschneider, L.; Haseltine, W. A.; Sodroski,
J . Proc. Natl. Acad. Sci. U.S.A. 1987, 84, 8120.
(3) (a) Humphries, M. J .; Matsumoto, K.; White, S. L.; Olden, K.
Cancer Res. 1986, 46, 5215. (b) Humphries, M. J .; Matsumoto, K.;
White, S. L.; Molyneux, R. J .; Olden, K. Cancer Res. 1988, 48, 1410.
(c) Nishimura, Y.; Kudo, T.; Kondo, S.; Takeuchi, T.; Tsuruoka, T.;
Fukuyasu, H.; Shibahara, S. J . Antibiot. 1994, 47, 101. (d) Nishimura,
Y.; Satoh, T.; Kondo, S.; Takeuchi, T.; Azetaka, M.; Fukuyasu, H.;
Iizuka, Y.; Shibahara, S. J . Antibiot. 1994, 47, 840. (e) Atsumi, S.;
Nosaka, C.; Ochi, Y.; Iinuma, H.; Umezawa, K. Cancer Res. 1993, 53,
4896.
(8) Inouye, S.; Tsuruoka, T.; Niida, T. J . Antibiot. 1966, 19, 288.
(9) Miyake, Y.; Ebata, M. J . Antibiot. 1987, 40, 122.
(10) Homenschutz, L. D.; Bell, E. A.; J ewest, P. J .; Leworthy, D. P.;
Pryce, R. J .; Arnold, E.; Clardy, J . Phytochemistry 1981, 20, 811.
(11) Colegate, S. M.; Dorling, P. R.; Huxtable, C. R. Aust. J . Chem.
1979, 32, 2257.
(12) Nishimura, Y. In Studies in Natural Products Chemistry; Atta-
ur-Rahman, Ed.; Elsevier: Amsterdam, 1992; Vol. 10, p 495.
(13) Winkler, D. A.; Holan, G. J . Med. Chem. 1989, 32, 2084.
(14) Knapp, S.; Dhar, T. G. M. J . Org. Chem. 1991, 56, 4096.
(15) (a) King, S. B.; Ganem, B. J . Am. Chem. Soc. 1991, 113, 5089.
(b) Trost, B. M.; Van Vranken, D. L. J . Am. Chem. Soc. 1991, 113,
6317. (c) Ogawa, S.; Yuming, Y. J . Chem. Soc., Chem. Commun. 1991,
890.
(4) Denis, J . W. Cancer Res. 1986, 46, 5131.
(16) Li, C.; Fuchs, P. L. Tetrahedron Lett. 1994, 35, 5121.
(17) King, S. B.; Ganem, B. J . Am. Chem. Soc. 1994, 116, 562.
(18) (a) Karpas, A.; Fleet, G. W. J .; Dwek, R. A.; Petursson, S.;
Namgoong, S. K.; Ramsden, N. G.; J acob, G. S.; Rademacher, T. W.
Proc. Natl. Acad. Sci. U.S.A. 1988, 85, 9229. (b) Taylor, D. L.; Sunkara,
P. S.; Liu, P. S.; Kang, M. S.; Bowlin, T. L.; Tyms, A. S. AIDS 1991, 5,
693. (c) Shimizu, H.; Tsuchie, H.; Yoshida, K.; Morikawa, S.; Tsuruoka,
T.; Yamamoto, H.; Ushijima, H.; Kitamura, T. AIDS 1990, 4, 975.
(5) Elbein, A. D.; Berninger, R. W. Biochem. J . 1985, 232, 759.
(6) (a) Aoyagi, T.; Yamamoto, T.; Kojiri, K.; Morishima, H.; Nagai,
M.; Hamada, M.; Takeuchi, T.; Umezawa, H. J . Antibiot. 1989, 42,
883. (b) Morishima, H.; Kojiri, K.; Yamamoto, T.; Aoyagi, T.; Naka-
mura, H.; Iitaka, Y. J . Antibiot. 1989, 42, 1008.
(7) Tropea, J . E.; Kaushal, G. P.; Pastuszak, I.; Mitchell, M.; Aoyagi,
T.; Molyneux, R. J .; Elbein, A. D. Biochemistry 1990, 29, 10062.
0022-3263/96/1961-0480$12.00/0 © 1996 American Chemical Society

Enantiodivergent Synthesis of Mannostatin Analogues
J . Org. Chem., Vol. 61, No. 2, 1996 481
Sch em e 1
Ch a r t 2
polyhydroxylated pyrrolidines, 1,4-dideoxy-1,4-imino-D-
mannitol (7) and 1,4,6-trideoxy-1,4-imino-D-mannitol (8),
show the specific inhibitory activity against mannosi-
dases, the natural ones, DMAP (9) and D-AB1 (10), are
specific glucosidase inhibitors (Chart 3).22 It is now clear
that both 7 and 8 superimpose very well on the energy-
minimized mannosyl cation, but 10 lacks the OH group
equivalent to the cation’s C2-OH.22b This suggests that
epimerization of the C2 hydroxy group of 1, which
equates to C3 of 7 and 8 and C2 of D-mannose or
mannosyl cation, would instill inhibitory activity against
the glucosidases.
On the basis of this supposition, 2-epimannostatin A
(12) and its enantiomer 13, as well as their positional
isomers 14 and 15, were targeted as specific glucosidase
inhibitors and as tools to probe the roles of methylthio
and amino substituents on the inhibition of enzymatic
hydrolysis.
Ch a r t 3
Since our interest in this class of inhibitors encom-
passed both enantiomerically pure stereoisomers and
positional isomers, we developed a highly flexible enan-
tiodivergent strategy utilizing both (S)-4-hydroxy-2-cy-
clopentenone (11) and its 4R-isomer 17,23 as outlined in
Scheme 1. Our approach to the desired analogues
involves, as the key steps, the regio- and stereoselective
introduction of three different heteroatom functions on
each carbon of the same mesointermediates, 18 and 19,
by differentiation of these positions. We report an
enantiodivergent route to the desired compounds starting
from (S)-4-((tert-butyldimethylsilyl)oxy)-2-cyclopentenone
(16).23
Resu lts a n d Discu ssion
The structure of 1 is different from other well-
documented mannosidase inhibitors such as 1-deoxy-
mannojirimycin,19 swainsonine,11 kifunensine,20 and man-
noamidrazone21 which closely resemble D-mannose or
mannopyranosyl cation 3. King and Ganem17 have noted
that 1 resembles â-D-mannopyranosylamine (4), a com-
petitive inhibitor of mannosidase (Chart 2). They also
found that mannostatin sulfone 5 showed the similar
activity to 1 for jack bean R-mannosidase. They synthe-
sized 3-epimannostatin sulfone 6 for the purpose of
transforming 1 from a mannosidase inhibitor to a glu-
cosidase inhibitor. However, 6 showed no significant
inhibition against almond â-glucosidase or jack bean
R-mannosidase. A synthetic antipode of 1 also had little
affect on the R-mannosidases.17 While the synthetic
Reduction of 16 with diisobutylaluminum hydride
followed by protection gave 21 (Scheme 2). Compound
21 was effectively converted to the pivotal intermediate,
mesotetrol 23, by the sequence of Woodward reaction,24
methanolysis and protection with an isopropylidene
group. Assignment of the relative stereochemistry of 23
was based on nuclear Overhauser effects (NOEs), which
were evident between 7-CH3 and 2-H, 7-CH3 and 3-H,
(22) (a) Fleet, G. W. J .; Nicholas, S. J .; Smith, P. W.; Evans, S. V.;
Fellows, L. E.; Nosh, R. J . Tetrahedron Lett. 1985, 26, 3127. (b)
Winkler, D. A.; Holan, G. J . Med. Chem. 1989, 32, 2084.
(23) Optically pure 16 ([R]23 -65.4° (c 0.96, CH3OH)) and its 4R-
D
isomer ([R]22 +67.4° (c 0.4, CH3OH)) were kindly donated from
D
Institute for Bio-medical Research, Teijin Limited: (a) Tanaka, T. J pn.
Pat. 54-163510; J apan Kokai 56-86128. (b) Tanaka, T.; Kurozumi, S.;
Toru, T.; Miuya, S.; Kobayashi, M.; Ishimoto, S. Tetrahedron 1976,
32, 1713.
(19) Ezure, Y.; Ojima, K.; Kanno, K.; Miyazaki, K.; Yamada, N.;
Sugiyama, M.; Itoh, M.; Nakamura, T. J . Antibiot. 1988, 41, 1142.
(20) Kayakiri, H.; Takase, T.; Shibata, T.; Okamoto, M.; Terano, H.;
Hashimoto, M.; Tada,T.; Koda, S. J . Org. Chem. 1989, 54, 4015.
(21) Ganem, B.; Papandreou, G. J . Am. Chem. Soc. 1991, 113, 8989.
(24) (a) Ellington, P. S.; Hey, D. G.; Meakins, G. U. J . Chem. Soc. C
1966, 1327. (b) Kametani, T.; Tsubuki, M.; Nemoto, H. Tetrahedron
Lett. 1980, 21, 4855.

482 J . Org. Chem., Vol. 61, No. 2, 1996
Nishimura et al.
Sch em e 2
8-CH3 and 1-H, and 8-CH3 and 4-H. The differentiation
of C1 and C4 of meso 23 was accomplished by selective
removal of each protecting group. Catalytic hydrogenoly-
sis of 23 with Pd/C afforded 1-hydroxy derivative 24 in
good yield, while treatment with tetrabutylammonium
fluoride gave 4-hydroxy derivative 25 quantitatively.
Treatment of 24 with triphenylphosphine and diethyl
azodicarboxylate smoothly eliminated the hydroxy group
to provide 26. The amino-hydroxylation of 26 was
successfully achieved by a silver acetate-iodine reac-
tion,25 displacement of the iodo group of the appropriately
protected derivative with an azido group, and hydro-
genolysis, in good yield. The stereochemistry of 27 was
established by NOE experiments, which revealed en-
hancements between 4-H and 1-H, 4-H and 2-H, 3-H and
5-H, 7-CH3 and 1-H, 7-CH3 and 2-H, 8-CH3 and 3-H, and
8-CH3 and 5-H. This stereochemical assignment was
later confirmed by X-ray crystallographic analysis of 47
(vide infra).
The last issue was the introduction of the methylthio
group to the desired position of thus obtained aminocy-
clitol 31. A problem arose, however, as removal of the
isopropylidene group of 31 proceeded without chemose-
lectivity, and substitution of sulfonates of the correspond-
ing monocyclic aminocyclitol with nucleophiles such as
methylthio or thioacetyl was accompanied by elimination
of the hydroxy group at the position under consideration.
This was circumvented by nucleophilic substitution of the
cyclic sulfate function of the fused tricyclic system with
sodium thiomercaptide. The desired compound 36 was
effectively obtained by the successive removal of the
O-tert-butyldimethylsilyl group, cyclic carbamate forma-
tion with NaH, protection of the hydroxy group, acid
hydrolysis, and cyclic sulfate formation26 by treatment
(25) (a) Kim, B. M.; Sharpless, K. B. Tetrahedron Lett. 1989, 30,
655. (b) Gao, Y.; Sharpless, K. B. J . Am. Chem. Soc. 1988, 110, 7538.
(26) Kuroki, R.; Weaver, L. H.; Matthews, B. W. Science 1993, 262,
2030.

Enantiodivergent Synthesis of Mannostatin Analogues
Sch em e 3
J . Org. Chem., Vol. 61, No. 2, 1996 483
with SOCl2 and pyridine in CH2Cl2, followed by oxidation
with RuCl3 and NaIO4 in CCl4-CH3CN-H2O. The
sulfate 36 smoothly underwent the nucleophilic displace-
ment with sodium thiomercaptide to generate 37 and 38
in a 1:1 ratio after hydrolysis with catalytic H2SO4 in
THF. The mixture was easily separated by preparative
thin-layer chromatography. The regiochemistry of 37
To determine whether epimerization at C2 and inver-
sion of absolute stereochemistry of 1 lead to an alteration
of enzyme specificity, 12 and its antipode 13 as well as 1
were assayed against bakers’ yeast R-glucosidase, almond
â-glucosidase, jack bean R-mannosidase, snail â-man-
nosidase, Escherichia coli R-galactosidase, Saccharomyces
fragilis â-galactosidase, and bovine liver â-glucuronidase.
The antipode 13 only affected almond â-glucosidase (IC50
8 µg/mL). Neither 12 nor 13 significantly inhibited any
of these enzymes (IC50 >100 µg/mL). The position
isomers 14 and 15 also showed no inhibitory activity
against these enzymes. Compound 1 proved to be a
specific inhibitor for jack bean R-mannosidase (IC50 0.04
µg/mL).
1
was determined by the aid of H-1H shift correlation
(COSY), 1H-13C COSY and heteronuclear multiple bond
correlation (HMBC) experiments. The strong correla-
tions between SCH3-H (2.21 ppm) and C-4 (55.54 ppm)
and between 4-H (2.88 ppm) and SCH3-C (14.27 ppm)
were observed in the HMBC, while no correlations
between SCH3-H and C-5 and between 5-H and SCH3-C
were observed. Removal of the protecting groups of 37
and 38 by alkaline and acid hydrolysis resulted in
2-epimannostatin hydrochloride 12 and its positional
isomer 14, respectively. Their enantiomers 13 and 15
were also successfully obtained from 25 by a similar
sequence of reactions varying in the removal of the
O-benzyl group of 49 and 50 with trimethylsilyl iodide.
Part of a series of enantiomers, cyclic carbamate 47 was
crystallized from ethyl acetate-methanol to give a single
crystal for X-ray diffraction analysis. The X-ray analysis
clearly indicated the desired absolute stereochemistry.27
The regiochemistry of 49 and 50 was also clarified by
HMBC experiments, which showed strong correlations
between SCH3-H (C) and C-4 (4-H) and between SCH3-H
(C) and C-5 (5-H), respectively. HMBC spectra of 13 and
15 also showed strong correlations between SCH3-H (C)
and C-5 (5-H), indicative of the regiochemistries shown
in Scheme 3.
Clearly, the configuration at C2 as well as the absolute
stereochemistry of 1 plays an important role in mannosi-
dase inhibition. Molecular modeling was undertaken to
understand the structure-inhibition relation of 13. The
structures were optimized first with molecular mechanics
(MM2) and then with PM3 in MOPAC. Molecular
modeling revealed that 13 superimposes well on the chair
form of â-D-glucopyranose and has its three hydroxyl
groups lying in the same region of space as C2, C3, and
C4 of the glucose. The C4-NH2 group of 13 would interact
with the amino acid residue of the enzyme instead of the
water molecule which participates in hydrolysis26 (Chart
4). These results would suggest that 13 mimics glucopy-
ranoside in ground-state binding to glucosidases and
thereby inhibits the enzymatic reaction.
The enantiodivergent route to mannostatin A ana-
logues presented here should offer a useful approach to
these multifunctionalized cyclopentanes which can be-
have as carbohydrate mimics, promising to be potent
glycosidase inhibitors. The synthetic intermediates are
(27) The authors have deposited atomic coordinates for structure
47 with the Cambridge Crystallographic Data Center. The coordinates
can be obtained, on request, from the Director, Cambridge Crystal-
lographic Data Center, 12 Union Road, Cambridge, CB2 IEZ, U.K.

484 J . Org. Chem., Vol. 61, No. 2, 1996
Nishimura et al.
The oil was dissolved in dry methanol (92 mL), and sodium
methoxide in methanol (1 M, 5 mL) was added to the mixture.
After being stirred at room temperature for 30 min, evapora-
tion of the solvent gave an oil, which was subjected to column
chromatography on silica gel. Elution with chloroform-
Ch a r t 4. Su p er im p osition of 2-Ep im a n n osta tin A
En a n tiom er (13) a n d â-D-Glu cop yr a n ose. Hyd r ogen
Atom s Ar e Om itted for Cla r ity
methanol (70:1) gave an oil of 22 (5.4 g, 83%): [R]25 -2.9° (c
D
0.5, CHCl3); NMR (CDCl3, 270 MHz) δ 0.05 and 0.06 (each
3H, s), 0.88 (9H, s), 1.53 (1H, dt, J ) 7.0 and 13.5 Hz), 2.3-
2.5 (3H, m), 3.82 (1H, dt, J ) 4.3 and 7.0 Hz), 4.01 (1H, dt, J
) 5.0 and 7.0 Hz), 4.55 (2H, t, J ) 11.9 Hz), and 7.2-7.4 (5H,
m); mass spectrum (FAB+) m/ z (relative intensity) 339 (M +
H)+ (61), 91 (100), 73 (81).
(1R,2S,3S,4S)-1-O-Ben zyl-4-O-(ter t-bu tyld im eth ylsilyl)-
2,3-O-isop r op ylid en ecyclop en ta n e-1,2,3,4-tetr ol (23). To
a solution of 22 (3.3 g, 9.8 mmol) in CH2Cl2 (40 mL) were added
2,2-dimethoxypropane (4 mL, 32 mmol) and D-camphor-10-
sulfonic acid (160 mg, 0.69 mmol), and the mixture was stirred
at room temperature for 30 min. After addition of a saturated
aqueous NaHCO3 solution (10 mL) and dilution with CH2Cl2
(100 mL), the mixture was washed with water, dried over
MgSO4, and filtered. Evaporation of the solvent gave an oil,
which was subjected to column chromatography on silica gel.
Elution with CHCl3 gave an oil of 23 (3.5 g, 95%): [R]25D -4.6°
(c 0.9, CHCl3); NMR (CDCl3, 270 MHz) δ 0.07 and 0.09 (each
3H, s), 0.88 (9H, s), 1.29 and 1.43 (each 3H, s), 1.88 (1H, dt
with small couplings, J ) 5.4 and 13.9 Hz), 2.21 (1H, dt, J )
5.4 and 13.9 Hz), 3.82 (1H, dt, J ) 2.0 and 5.4 Hz), 4.15 (1H,
dt, J ) 2.0 and 5.4 Hz), 4.46 (1H, broad d with a small
coupling, J ) 6.6 Hz), 4.56 (2H, t, J ) 12.5 Hz), 4.63 (1H, broad
d with small couplings, J ) 6.6 Hz), and 7.15-7.4 (5H, m);
mass spectrum (FAB+) m/ z (relative intensity) 379 (M + H)+
(25), 229 (53), 129 (53), 91 (100), 73 (91).
(1R,2S,3S,4S)-4-O-(ter t-Bu t yld im et h ylsilyl)-2,3-O-iso-
p r op ylid en ecyclop en ta n e-1,2,3,4-tetr ol (24). The solution
of 23 (1.85 g, 4.9 mmol) in a mixture of ethyl acetate (30 mL)
and methanol (60 mL) was stirred with 10% Pd/C (1 g) under
a hydrogen atmosphere for 7 h. The catalysts were filtered
off, and the filtrate was evaporated to give an oil of 26 (1.46
g, 100%): [R]25D -4.5° (c 0.98, CHCl3); NMR (CDCl3, 400 MHz)
δ 0.12 and 0.13 (each 3H, s), 0.89 (9H, s), 1.29 and 1.39 (each
3H, s), 1.77 (1H, broad d with small couplings, J ) 14.2 Hz),
2.09 (1H, broad dt with small couplings, J ) 4.1 and 14.2 Hz),
3.21 (1H, d, J ) 10.9 Hz), 4.09 (1H, broad dd, J ) 4.1 and
10.9 Hz), 4.13 (1H, broad d, J ) 4.1 and 5.4 Hz), 4.51 (1H, dd,
J ) 1.5 and 5.4 Hz), 4.66 (1H, dd, J ) 2.0 and 5.4 Hz); mass
spectrum (FAB+) m/ z (relative intensity) 289 (M + H)+ (100),
231 (30), 173 (24), 73 (37).
highly flexible in terms of alteration of the diastereo- and
enantiomerism and the regioplacement of the functional-
ity.
Exp er im en ta l Section
(1R,4S)-4-O-(ter t-Bu tyld im eth ylsilyl)cyclop en t-2-en e-
1,4-d iol (20). To a solution of 16 (4.87 g, 23 mmol) in dry
benzene (97 mL) was added dropwise a solution of diisobuty-
laluminum hydride (DIBALH) in toluene (1 M, 23 mL, 23
mmol) at 0 °C, and the mixture was stirred at the same
temperature for 2 h. After the reaction was quenched with a
large excess of saturated aqueous Na2SO4 solution, the result-
ing insoluble matters were filtered off. Evaporation of the
solvent gave an oil, which was dissolved in chloroform. The
solution was washed with water, dried over MgSO4, and
filtered. The filtrate was evaporated to give an oil, which was
subjected to column chromatography on silica gel. Elution
with chloroform-methanol (70:1) gave a colorless liquid of 20
(4.4 g, 90%): [R]28 -33.6° (c 0.35, CHCl3); NMR (CDCl3, 400
D
MHz) δ 0.09 (6H, s), 0.89 (9H, s), 1.52 (1H, dt, J ) 4.4 and
13.7 Hz), 1.68 (1H, broad d, J ) 8.8 Hz), 2.69 (1H, dt, J ) 6.8
and 13.7 Hz), 4.59 (1H, broad m), 4.66 (1H, m), 5.89 (1H, broad
d with small couplings, J ) 5.4 Hz), and 5.95 (1H, broad d
with small couplings, J ) 5.4 Hz); mass spectrum (FAB+) m/ z
(relative intensity) 215 (M + H)+ (11), 197 (57), 107 (28), 73
(100).
(1R,4S)-1-O-Ben zyl-4-O-(ter t-bu tyld im eth ylsilyl)cyclo-
p en t-2-en e-1,4-d iol (21). To a solution of 20 (4.3 g, 20 mmol)
in dry THF was added NaH (60% in oil, 1.7 g, 42 mmol) at
-10 °C. After the mixture was stirred at room temperature
for 30 min, tetrabutylammonium iodide (3.4 g, 9.2 mmol) and
benzyl bromide (7.1 mL, 60 mmol) were added to the mixture.
Then the resulting mixture was stirred at room temperature
for 1 h. After quenching with a small amount of water at -10
°C, evaporation of the solvent gave an oil, which was dissolved
in chloroform. The solution was washed with water, dried over
MgSO4, and filtered. Evaporation of the filtrate gave an oil,
which was subjected to column chromatography on silica gel.
Elution with dichloromethane gave a liquid of 21 (6 g, 98%):
[R]27D -2.2° (c 1.0, CHCl3); NMR (CDCl3, 270 MHz) δ 0.08 (6H,
broad s), 0.90 (9H, s), 1.65 (1H, dt, J ) 5.4 and 13.2 Hz), 2.68
(1H, dt, J ) 6.6 and 13.2 Hz), 4.45 (1H, m), 4.52 and 4.57 (2H,
ABq, J ) 11.9 Hz), 4.59 (1H, m), 5.89 (1H, m), 5.96 (1H, m,)
and 7.1-7.4 (5H, m); mass spectrum (FAB+) m/ z (relative
intensity) 305 (M + H)+ (9), 197 (100), 165 (31), 91 (76), 75
(60), 73 (62).
(1R ,2R ,3S ,4S )-1-O-Be n zyl-4-O-(t er t -b u t yld im e t h yl-
silyl)cyclop en ta n e-1,2,3,4-tetr ol (22). To a solution of 21
(5.9 g, 19 mmol) in acetic acid (120 mL) were added CH3CO2-
Ag (14 g, 84 mmol) and iodine (9.7 g, 38 mmol), and the
mixture was stirred at room temperature for 1.5 h. After
addition of 4% aqueous acetic acid solution, the mixture was
further stirred at 50 °C for 4 h. After removal of insoluble
matters by filtration, the filtrate was evaporated to give an
oil. The oil was dissolved in CHCl3, and the solution was
washed with saturated aqueous NaHCO3 solution, dried over
MgSO4, and filtered. Evaporation of the filtrate gave an oil,
which was subjected to column chromatography on silica gel.
Elution with chloroform-methanol (100:1) gave an oil (6.1 g).
(1R,2S,3R,4S)-1-O-Ben zyl-2,3-O-isop r op ylid en ecyclo-
p en ta n e-1,2,3,4-tetr ol (25). To a solution of 23 (1.7 g, 4.5
mmol) in THF (18 mL) was added tetrabutylammonium
fluoride in THF (1 M, 6.8 mL, 6.8 mmol). After stirring at
room temperature for 30 min, evaporation of the solvent gave
an oil. The oil was dissolved in CH2Cl2, and the solution was
washed with water, dried over MgSO4, and filtered. Evapora-
tion of the filtrate gave an oil, which was subjected to column
chromatography on silica gel. Elution with chloroform-
methanol (150:1) gave an oil of 25 (1.3 g, 100%): [R]25 0° (c
D
1.0, CHCl3); NMR (CDCl3, 270 MHz) δ 1.21 and 1.30 (each
3H, s), 1.87 (1H, broad d, J ) 14.7 Hz), 2.02 (1H, dt, J ) 4.4
and 14.7 Hz), 2.80 (1H, broad d, J ) 10.9 Hz), 3.91 (1H, broad
d, J ) 4.4 Hz), 4.02 (1H, broad dd, J ) 4.4 and 10.9 Hz), 4.46
and 4.55 (2H, ABq, J ) 11.9 Hz), 4.53 (1H, dd, J ) 1.6 and
5.6 Hz), 4.64 (1H, dd, J ) 1.7 and 5.6 Hz), and 7.1-7.3 (5H,
m); mass spectrum (FAB+) m/ z (relative intensity) 265 (M +
H)+ (37), 107 (25), 91 (100).
(1S,2S,3S)-3-O-(ter t-Bu t yld im et h ylsilyl)-2,3-O-isop r o-
p ylid en ecyclop en t-4-en e-1,2,3-tr iol (26). To a solution of
24 (2.8 g, 9.7 mmol) in dry benzene (77 mL) were added
triphenylphosphine (10.2 g, 39 mmol) and diethyl azodicar-
boxylate (6.1 mL, 39 mmol), and the mixture was stirred at
room temperature overnight. After addition of water, evapo-
ration of the solvent gave an oil. The oil was dissolved in
CHCl3, and the solution was washed with water, dried over
MgSO4, and filtered. Evaporation of the filtrate gave an oil,
which was subjected to column chromatography on silica gel.
Elution with CHCl3 gave a liquid of 7 (1.9 g, 72%): [R]23D -116°

Enantiodivergent Synthesis of Mannostatin Analogues
J . Org. Chem., Vol. 61, No. 2, 1996 485
(c 0.48, CHCl3); NMR (CDCl3, 270 MHz) δ 0.09 and 0.12 (each
3H, s), 0.89 (9H, s), 1.24 and 1.29 (each 3H, s), 4.44 (1H, d, J
) 5.4 Hz), 4.74 (1H, m), 5.26 (1H, broad d with small couplings,
J ) 5.4 Hz), 5.78 (1H, broad d with small couplings, J ) 5.9
Hz), and 5.90 (1H, broad d with small couplings, J ) 5.9 Hz);
mass spectrum (FAB+) m/ z (relative intensity) 271 (M + H)+
(45), 213 (88), 73 (100).
(1S,2S,3R,4R,5R)-5-((ter t-Bu toxyca r bon yl)a m in o)-3,4-
b is-O-(ter t-b u t yld im et h ylsilyl)-1,2-O-isop r op ylid en ecy-
clop en ta n e-1,2,3,4-tetr ol (31). The solution of 30 (1.0 g, 2.3
mmol) in a mixture of ethyl acetate (25 mL) and methanol (25
mL) was stirred with 10% Pd/C (1 g) under a hydrogen
atmosphere for 3 h. The catalysts were filtered off, and the
filtrate was evaporated to give a residue, which was dissolved
in dry CH2Cl2 (21 mL). To the solution were added N,N-
diisopropylethylamine (5.6 mL, 32 mmol) and di-tert-butyl
dicarbonate (2.5 mL, 11 mmol), and the mixture was stirred
at room temperature overnight. Evaporation of the solvent
gave an viscous oil, which was dissolved in CH2Cl2. The
solution was washed with water, dried over MgSO4, and
filtered. Evaporation of the filtrate gave an oil. The oil was
subjected to column chromatography on silica gel. Elution
(1R,2S,3R,4S,5S)-4-O-Acetyl-3-O-(ter t-bu tyld im eth ylsi-
lyl)-5-iod o-1,2-O-isop r op ylid e n e cyclop e n t a n e -1,2,3,4-
tetr ol (27). To a solution of 26 (2.3 g, 8.5 mmol) in dry ether
(75 mL) were added iodine (3.4 g, 13 mmol) and CH3CO2Ag
(3.2 g, 19 mmol), and the mixture was stirred at room
temperature for 48 h. After removal of insoluble matters,
evaporation of the solvent gave an oil. The oil was dissolved
in CH2Cl2, and the solution was washed with water, dried over
MgSO4, and filtered. Evaporation of the filtrate gave an oil,
which was subjected to column chromatography on silica gel.
Elution with toluene-acetone (40:1) gave an oil of 27 (3.5 g,
with chloroform gave an oil of 31 (920 mg, 79%): [R]25 +2.5°
D
(c 1.3, CHCl3); NMR (CDCl3, 400 MHz) δ 0.07, 0.08, 0.09 and
0.10 (each 3H, s), 0.87 and 0.91 (each 9H, s), 1.28 and 1.45
(each 3H, s), 1.45 (9H, s), 3.92 (1H, broad d, J ) 4.4 Hz), 3.97
(1H, s), 4.24 (1H, broad dt, J ) 5.9 and 9.8 Hz), 4.32 (1H, dd,
J ) 1.0 and 5.9 Hz), 4.64 (1H, t, J ) 5.9 Hz), and 5.16 (1H,
broad d, J ) 9.8 Hz); mass spectrum (FAB+) m/ z (relative
intensity) 518 (M + H)+ (6), 418 (70), 404 (28), 73 (100), 57
(48).
90%): [R]23 -12.8° (c 0.91, CHCl3); NMR (CDCl3, 270 MHz)
D
δ 0.10 and 0.11 (each 3H, s), 0.90 (9H, s), 1.28 and 1.49 (each
3H, s), 2.09 (3H, s), 4.04 (1H, dd, J ) 4.0 and 6.3 Hz), 4.11
(1H, dd, J ) 2.3 and 4.6 Hz), 4.44 (1H, dd, J ) 2.3 and 6.8
Hz), 4.98 (1H, dd, J ) 4.0 and 6.8 Hz), 5.33 (1H, dd, J ) 4.6
and 6.3 Hz); mass spectrum (FAB+) m/ z (relative intensity)
457 (M + H)+ (21), 399 (81), 281 (28), 117 (100), 73 (95).
(1S,2R,3S,4R,5S)-5-((ter t-Bu t oxyca r bon yl)a m in o)-1,2-
O-isop r op ylid en ecyclop en ta n e-1,2,3,4-tetr ol (32). To a
solution of 31 (900 mg, 1.7 mmol) in dry THF (18 mL) was
added tetrabutylammonium fluoride in THF (1 M, 4 mL, 4
mmol), and the mixture was stirred at room temperature for
3 h. Evaporation of the solvent gave an oil, which was
dissolved in CH2Cl2. The solution was washed with water,
dried over MgSO4, and filtered. Evaporation of the filtrate
gave an oil. The oil was subjected to column chromatography
on silica gel. Elution with chloroform-methanol (30:1) gave
a solid of 32 (430 mg, 86%), which was crystallized from ethyl
acetate to give colorless crystals: mp 156-157 °C; [R]24D -18.3°
(c 1.4, CHCl3); NMR (CDCl3, 400 MHz) δ 1.32 and 1.48 (each
3H, s), 1.47 (9H, s), 2.34 (1H, broad d, J ) 8.8 Hz), 3.01 (1H,
broad s), 3.95 (1H, broad dd, J ) 4.4 and 8.8 Hz), 4.18 (1H,
broad s), 4.27 (1H, broad dt, J ) 4.4 and 8.8 Hz), 4.52 (1H, dd,
J ) 1 and 5.4 Hz), 4.71 (1H, t, J ) 5.4 Hz), and 5.33 (1H,
broad d, J ) 8.8 Hz); mass spectrum (FAB+) m/ z (relative
intensity) 290 (M + H)+ (51), 234 (67), 190 (100), 57 (42). Anal.
Calcd for C13H23NO6: C, 53.96; H, 8.01; N, 4.58. Found: C,
53.69; H, 8.30; N, 4.31.
(1R,2S,3S,4S,5R)-3-O-(ter t-Bu tyld im eth ylsilyl)-5-iod o-
1,2-O-isopr opyliden ecyclopen tan e-1,2,3,4-tetr ol (28). Com-
pound 27 (3.1 g, 6.8 mmol) was dissolved in methanol
saturated with NH3 (31 mL), and the solution was allowed to
stand at room temperature overnight. Evaporation of the
solvent gave an oil, which was subjected to column chroma-
tography on silica gel. Elution with CHCl3-CH3OH (25:1)
gave an oil of 28 (2.5 g, 89%): [R]23 -12.2° (c 0.36, CHCl3);
D
NMR (CDCl3, 270 MHz) δ 0.10 and 0.11 (each 3H, s), 0.80 (9H,
s), 1.27 and 1.47 (each 3H, s), 2.45 (1H, broad d, J ) 5.8 Hz),
3.99 (1H, dd, J ) 5.3 and 7.9 Hz), 4.00 (1H, dd, J ) 3.1 and
5.8 Hz), 4.08 (1H, broad dt, J ) 5.8 and 7.9 Hz), 4.35 (1H, dd,
J ) 3.1 and 7.1 Hz), and 4.82 (1H, dd, J ) 5.3 and 7.1 Hz),
mass spectrum (FAB+) m/ z (relative intensity) 415 (M + H)+
(15), 257 (21), 215 (37), 73 (100), 59 (21).
(1R,2R,3R,4S,5S)-3,4-Bis-O-(ter t-bu tyld im eth ylsilyl)-5-
iodo-1,2-O-isopr opyliden ecyclopen tan e-1,2,3,4-tetr ol (29).
To a solution of 28 (2.0 g, 4.8 mmol) in dry DMF (1.8 mL) were
added imidazole (1.3 g, 19 mmol) and tert-butyldimethylsilyl
chloride (2.2 g, 14 mmol), and the mixture was stirred at room
temperature for 2 h. After dilution with CHCl3 (200 mL), the
solution was washed with water, dried over MgSO4, and
filtered. Evaporation of the filtrate gave an oil. The oil was
subjected to column chromatography on silica gel. Elution
(3a R ,3b R ,6a R ,7S,7a R )-7-H yd r oxy-2,2-d im e t h yl[1,3]-
d ioxolo[4,5-d ]cyclop en t[4,5-d ]oxa zolid in -5-on e (33). To
a solution of 32 (398 mg, 1.4 mmol) in dry DMF (8 mL) was
added NaH (60% in oil, 165 mg, 4.1 mmol) at -20 °C, and the
mixture was stirred at room temperature overnight. After
quenching with saturated aqueous NH4Cl solution, evapora-
tion of the solvent gave a viscous solid. The solid was dissolved
in chloroform, and the solution was washed with water, dried
over MgSO4, and filtered. Evaporation of the solvent gave a
solid. The solid was subjected to column chromatography
on silica gel. Elution with chloroform-methanol (7:1) gave a
solid of 33 (263 mg, 89%), which was crystallized from
with chloroform gave an oil of 29 (2.1 g, 82%): [R]25 +11.6°
D
(c 1.8, CHCl3); NMR (CDCl3, 400 MHz) δ 0.09, 0.10, 0.12, and
0.17 (each 3H, s), 0.90 and 0.91 (each 9H, s), 1.25 and 1.56
(each 3H, s), 3.87 (1H, dd, J ) 5.4 and 7.8 Hz), 3.93 (1H, dd,
J ) 2.5 and 5.4 Hz), 4.15 (1H, dd, J ) 5.4 and 7.8 Hz), 4.27
(1H, dd, J ) 2.5 and 7.0 Hz), and 4.83 (1H, dd, J ) 5.4 and
7.0 Hz); mass spectrum (FAB+) m/ z (relative intensity) 529
(M + H)+ (5), 413 (66), 285 (74), 229 (76), 215 (98), 147 (100),
133 (91), 81 (87), 75 (89), 59 (90).
chloroform to give colorless crystals: mp 125-126 °C: [R]23
D
-36° (c 0.66, CHCl3); NMR (CDCl3, 400 MHz) δ 1.35 and 1.50
(each 3H, s), 4.25 (1H, t, J ) 6.6 Hz), 4.54 (1H, s), 4.63 (1H, d,
J ) 5.6 Hz), 4.69 (1H, t, J ) 5.6 Hz), 4.88 (1H, d, J ) 7.0 Hz),
5.17 (1H, broad s); mass spectrum (FAB+), m/ z (relative
intensity) 216 (M + H)+ (52), 107 (100), 89 (80), 77 (67). Anal.
Calcd for C9H13NO5: C, 50.23; H, 6.09; N, 6.51. Found: C,
49.97; H, 6.25; N, 6.73.
(1S,2S,3R,4R,5R)-5-Azid o-3,4-bis-O-(ter t-bu tyld im eth -
ylsilyl)-1,2-O-isop r op ylid en ecyclop en ta n e-1,2,3,4-tetr ol
(30). To a solution of 29 (2.0 g, 3.8 mmol) in dry dimethyl
sulfoxide (30 mL) was added NaN3 (4 g, 62 mmol), and the
mixture was stirred at 150 °C for 2.5 h. After dilution with
ether (500 mL), the solution was washed with water, dried
over MgSO4, and filtered. Evaporation of the filtrate gave an
oil. The oil was subjected to column chromatography on
silica gel. Elution with chloroform gave an oil of 30 (1.1 g,
(3a S ,3b R ,6a R ,7S ,7a S )-7-((Be n zyloxy)m e t h oxy)-2,2-
d im eth yl[1,3]d ioxolo[4,5-a ]cyclop en t[4,5-d ]oxa zolid in -5-
on e (34). To a solution of 33 (236 mg, 4.6 mmol) in dry DMF
(2.5 mL) were added N,N-diisopropylethylamine (1.5 mL, 8.6
mmol) and (benzyloxy)methyl chloride (0.31 mL, 2.2 mmol),
and the mixture was stirred at room temperature for 48 h.
After quenching with water, evaporation of the solvent gave
an oil. The oil was dissolved in chloroform, and the solution
was washed with water, dried over MgSO4, and filtered.
Evaporation of the filtrate gave an oil, which was subjected
to column chromatography on silica gel. Elution with
66%): [R]25 -69.4° (c 0.96, CHCl3); NMR (CDCl3, 400 MHz)
D
δ 0.07, 0.10, 0.13, and 0.15 (each 3H, s), 0.85 and 0.94 (each
9H, s), 1.30 and 1.52 (each 3H, s), 3.34 (1H, t, J ) 5.4 Hz),
4.02 (1H, broad dd, J ) 3.0 and 5.4 Hz), 4.05 (1H, d with a
small coupling, J ) 3.0 Hz), 4.30 (1H, d with a small coupling,
J ) 5.8 Hz), and 4.76 (1H, t, J ) 5.8 Hz); mass spectrum
(FAB+) m/ z (relative intensity) 444 (M + H)+ (8), 386 (38),
147 (76), 73 (100).

486 J . Org. Chem., Vol. 61, No. 2, 1996
Nishimura et al.
chloroform-methanol (15:1) gave a solid of 34 (215 mg, 58%),
7.40 (5H, m); 13C NMR (CDCl3) δ 14.27, 55.54, 57.79, 70.41,
76.75, 81.64, 89.26, 95.15, 128.10, 128.20, 128.26, 136.56,
158.40; mass spectrum (FAB+) m/ z (relative intensity) 326 (M
+ H)+ (90), 137 (98), 91 (100).
which was crystallized from ether to give colorless crystals:
mp 114-115 °C; [R]24 -43.2° (c 0.93, CHCl3); NMR (CDCl3,
D
400 MHz) δ 1.32 and 1.50 (each 3H, s), 4.16 (1H, dd with a
small coupling, J ) 5.9 and 7.8 Hz), 4.46 (1H, s), 4.58 (1H, t,
J ) 5.9 Hz), 4.63 (2H, s), 4.70 (1H, d, J ) 5.9 Hz), 4.83 (2H,
s), 4.84 (1H, d, J ) 7.8 Hz), 5.25 (1H, broad s), and 7.2-7.4
(5H, m); mass spectrum (FAB+) m/ z (relative intensity) 336
(M + H)+ (56), 138 (94), 107 (56), 91 (100). Anal. Calcd for
C17H21NO6: C, 60.88; H, 6.31; N, 4.18. Found: C, 60.61; H,
6.52; N, 4.33.
38: [R]23 +64.6° (c 0.8, CHCl3); NMR (CDCl3, 400 MHz) δ
D
2.22 (3H, s), 3.06 (1H, dd, J ) 4.4 and 10.3 Hz), 3.57 (1H, broad
s), 4.16 (1H, dd, J ) 5.9 and 10.3 Hz), 4.2-4.3 (2H, m), 4.62
and 4.77 (2H, ABq, J ) 11.7 Hz), 4.81 (1H, dd, J ) 6.8 and
14.7), 4.83 and 4.85 (2H, ABq), 6.38 (1H, s), and 7.25-7.40
(5H, m); mass spectrum (FAB+) m/ z (relative intensity) 348
(M + Na)+ (25), 326 (M + H)+ (30), 296 (33), 218 (82), 91 (100).
(1R,2S,3R)-1-O-Ben zyl-2,3-O-isop r op ylid en ecyclop en t-
4-en e-1,2,3-tr iol (39). Procedures used were similar to those
used for the preparation of 26 from 24 described above; the
yield was 95%; [R]25D +101° (c 0.96, CHCl3); NMR (CDCl3, 270
MHz) δ 1.37 and 1.41 (each 3H, s), 4.57 (1H, m), 4.57 and 4.70
(2H, ABq, J ) 11.7 Hz), 4.65 (1H, d, J ) 5.6 Hz), 5.28 (1H,
broad d with small couplings, J ) 5.6 Hz), 5.93 (1H, broad d
with small couplings, J ) 5.1 Hz), 6.05 (1H, broad d with small
couplings, J ) 5.1 Hz), and 7.2-7.4 (5H, m); mass spectrum
(FAB+) m/ z (relative intensity) 247 (M + H)+ (6), 189 (76), 91
(100), 69 (51), 55 (58).
(3a R,4S,5S,6R,6a R)-6-((Ben zyloxy)m eth oxy)-4,5-d ih y-
d r oxycyclop en t[d ]oxa zolid in -2-on e (35). Compound 34
(107 mg, 0.32 mmol) was dissolved in 50% aqueous acetic acid
(3 mL), and the mixture was stirred at 70 °C for 2 h.
Evaporation of the solvent gave a solid of 35 (77 mg, 82%),
which was crystallized from methanol-water (5:1) to give
colorless crystals: mp 155-156 °C; [R]23D -16.4° (c 0.55, CH3-
OH); NMR (CD3OD, 400 MHz) δ 3.94 (1H, dd, J ) 4.6 and 5.4
Hz), 4.01 (1H, t, J ) 4.6 Hz), 4.16 (1H, dd, J ) 4.6 and 8.3
Hz), 4.25 (1H, dd, J ) 2.2 and 5.4 Hz), 4.64 (2H, t, J ) 12.2
Hz), 4.78 (1H, dd, J ) 2.2 and 8.3 Hz), 4.86 (2H, s), and 7.2-
7.4 (5H, m); mass spectrum (FAB+) m/ z (relative intensity)
296 (M + H)+ (64), 107 (86), 91 (100), 89 (68). Anal. Calcd
for C14H17NO6: C, 56.94; H, 5.80; N, 4.74. Found: C, 56.71;
H, 6.04; N, 4.59.
(1R,2S,3S,4S,5R)-1-O-Acet yl-2-O-b en zyl-5-iod o-3,4-O-
isop r op ylid en ecyclop en t a n e-1,2,3,4-t et r ol (40). Proce-
dures used were similar to those used for the preparation of
27 from 26; the yield was 82%; [R]23 -1.6° (c 0.48,CHCl3);
D
(3a S,3b S,6a R,7S,7a R)-7-((Ben zyloxy)m et h oxy)[1,3,2]-
d ioxa t h iolo[4,5-a ]cyclop en t [4,5-d ]oxa zolid in e-2,2,5-t r i-
on e (36). To a solution of 35 (78 mg, 0.26 mmol) in dry CH2Cl2
(3 mL) were added dry pyridine (0.15 mL, 1.9 mmol) and SOCl2
(0.024 mL, 0.33 mmol), and the mixture was stirred at room
temperature for 2 h. After dilution with CH2Cl2 (10 mL), the
solution was washed with water, dried over MgSO4, and
filtered. Evaporation of the filtrate gave an oil, which was
dissolved in CCl4-CH3CN-H2O (2:2:3, 4.5 mL). To the
solution were added RuCl3 (13 mg, 0.063 mmol) and NaIO4
(95 mg, 0.44 mmol), and the mixture was stirred at room
temperature for 1 h. After dilution with CH2Cl2 (10 mL), the
solution was washed with saturated aqueous NaCl solution,
dried over MgSO4, and filtered. Evaporation of the filtrate
gave an oil. The oil was subjected to preparative thin-layer
chromatography (PTLC) on silica gel developed with chloro-
form-methanol (10:1) to give a solid of 36 (69 mg, 73%), which
was crystallized from methanol to give colorless crystals: mp
122-123 °C; [R]24D -41.3° (c 0.75, CH3OH); NMR (CD3OD, 400
MHz) δ 4.61 (1H, dd, J ) 5.9 and 7.8 Hz), 4.65 (1H, d, J ) 2.0
Hz), 4.64 and 4.68 (2H, ABq, J ) 12.2 Hz), 4.91 (2H, s), 4.98
(1H, d with small couplings, J ) 7.8 Hz), 5.28 (1H, dd with
small coupling, J ) 2.0 and 5.9 Hz), 5.40 (1H, t, J ) 5.9 Hz)
and 7.2-7.4 (5H, m); mass spectrum (FAB+) m/ z (relative
intensity) 358 (M + H)+ (26), 107 (71), 91 (100), 89 (58), 77
(50). Anal. Calcd for C14H15NO8S: C, 47.05; H, 4.23; N, 3.92.
Found: C, 46.89; H, 4.41; N, 3.67.
NMR (CDCl3, 270 MHz) δ 1.29 and 1.49 (each 3H, s), 2.09 (3H,
s), 3.93 (1H, dd, J ) 2.0 and 4.8 Hz), 4.07 (1H, dd, J ) 4.3 and
6.4 Hz), 4.60 (1H, dd, J ) 2.0 and 6.6 Hz), 4.64 (2H, s), 4.98
(1H, dd, J ) 4.3 and 6.6 Hz), 5.54 (1H, dd, J ) 4.8 and 6.4
Hz), and 7.2-7.4 (5H, m); mass spectrum (FAB+) m/ z (relative
intensity) 433 (M + H)+ (31), 375 (36), 91 (100).
(1R ,2S ,3S ,4S ,5S )-2-O-Be n zyl-5-iod o-3,4-O-isop r op y-
lid en ecyclop en ta n e-1,2,3,4-tetr ol (41). Procedures used
were similar to those used for the preparation of 28 from 27;
the yield was 85%; [R]25 -2.9° (c 0.8, CHCl3); NMR (CDCl3,
D
270 MHz) δ 1.31 and 1.51 (each 3H, s), 2.55 (1H, broad d, J )
4.6 Hz), 3.84 (1H, dd, J ) 3.3 and 6.9 Hz), 3.94 (1H, dd, J )
6.0 and 9.2 Hz), 4.24 (1H, m), 4.51 (1H, dd, J ) 3.3 and 6.9
Hz), 4.64 and 4.72 (2H, ABq, J ) 11.7 Hz), 4.82 (1H, dd, J )
6.0 and 6.9 Hz), and 7.2-7.4 (5H, m); mass spectrum (FAB+)
m/ z (relative intensity) 391 (M + H)+ (23), 107 (24), 91 (100),
89 (33).
(1R,2S,3S,4S,5R)-2-O-Ben zyl-1-O-(ter t-b u t yld im et h yl-
silyl)-5-iod o-2,3-isop r op ylid e n e cyclop e n t a n e -1,2,3,4-
tetr ol (42). Procedures used were similar to those used for
the preparation of 29 from 28; the yield was 95%; [R]23D -5.2°
(c 0.35, CHCl3); NMR (CDCl3, 270 MHz) δ 0.09 and 0.16 (each
3H, s), 0.90 (9H, s), 1.30 and 1.53 (each 3H, s), 3.71 (1H, dd,
J ) 3.6 and 7.3 Hz), 3.88 (1H, dd, J ) 7.3 and 9.9 Hz), 4.19
(1H, dd, J ) 7.3 and 9.9 Hz), 4.40 (1H, dd, J ) 3.6 and 7.3
Hz), 4.55 and 4.68 (2H, ABq, J ) 11.4 Hz), 4.77 (1H, t, J ) 7.3
Hz), and 7.2-7.4 (5H, m); mass spectrum (FAB+) m/ z (relative
intensity) 505 (M + H)+ (18), 107 (33), 91 (100), 73 (85).
(1S,2S,3R,4R,5S)-5-Azid o-2-O-b en zyl-1-O-(ter t-b u t yl-
d im eth ylsilyl)-3,4-O-isop r op ylid en ecyclop en ta n e-1,2,3,4-
tetr ol (43). Procedures used were similar to those used for
the preparation of 30 from 29; the yield was 81%; [R]23D -86.5°
(c 0.45, CHCl3); NMR (CDCl3, 270 MHz) δ 0.12 and 0.13 (each
3H, s), 0.92 (9H, s), 1.33 and 1.56 (each 3H, s), 3.39 (1H, t, J
) 4.9 Hz), 3.80 (1H, dd, J ) 1.6 and 4.9 Hz), 4.07 (1H, t, J )
4.9 Hz), 4.37 (1H, dd, J ) 1.6 and 5.0 Hz), 4.62 (1H, broad t,
J ) 5.0 Hz), and 7.2-7.4 (5H, m); mass spectrum (FAB+) m/ z
(relative intensity) 420 (M + H)+ (4), 362 (36), 91 (100), 73
(91).
(3aS,4R,5R,6R,6aR)-6-((Ben zyloxy)m eth oxy)-5-h ydr oxy-
4-(m et h ylt h io)cyclop en t [d ]oxa zolid in -2-on e (37) a n d
(3a S,4S,5R,6S,6a R)-6-((Ben zyloxy)m eth oxy)-4-h yd r oxy-
5-(m eth ylth io)cyclop en t[d ]oxa zolid in -2-on e (38). A mix-
ture of 36 (52 mg, 0.15 mmol) and NaSCH3 (51 mg, 0.73 mmol)
in dry DMF (0.6 mL) was stirred under argon at room
temperature for 1 h. Evaporation of the solvent gave a viscous
solid, which was dissolved in CHCl3. The solution was washed
with saturated aqueous NaCl solution, dried over MgSO4, and
filtered. Evaporation of the filtrate gave an oil. The oil was
dissovled in a solution (1 mL) of a mixture of THF (46.4 mL),
H2O (15 µL), and H2SO4 (10 µL), and the solution was stirred
at room temperature overnight. After being stirred with
excess NaHCO3, the mixture was filtered through a Celite.
Evaporation of the filtrate gave an oil. The oil was subjected
to PTLC on silica gel developed with toluene-acetone (3:1) to
give a foam of 37 (18 mg, 38%) and a foam of 38 (19 mg, 40%).
(1S,2S,3R,4R,5S)-2-O-Ben zyl-5-((ter t-bu toxyca r bon yl)-
a m in o)-1-O-(t er t -b u t yld im e t h ylsilyl)-3,4-O-isop r op y-
lid en ecyclop en ta n e-1,2,3,4-tetr ol (44). Procedures used
were similar to those used for the preparation of 31 from 30;
the yield was 84%; [R]24 -1.4° (c 0.97, CHCl3); NMR (CDCl3,
D
37: [R]23 +34° (c 0.7, CHCl3); H NMR (CDCl3, 400 MHz) δ
270 MHz) δ 0.03 and 0.06 (each 3H, s), 0.89 (9H, s), 1.46 (9H,
s), 3.72 (1H, broad s), 4.12 (1H, broad d, J ) 5.3 Hz), 4.22 (1H,
dt, J ) 5.3 and 9.9 Hz), 4.45-4.60 (3H, m), 4.64 (1H, broad t,
J ) 5.3 Hz), 5.15 (1H, broad d, J ) 9.9 Hz), and 7.2-7.4 (5H,
m); mass spectrum (FAB+) m/ z (relative intensity) 494 (M +
H)+ (10), 394 (87), 380 (50), 91 (100).
D
2.21 (3H, s), 2.89 (1H, dd, J ) 7.3 and 10.3 Hz), 3.76 (1H, dd,
J ) 8.0 and 10.3 Hz), 3.82 (1H, broad s), 3.96 (1H, broad t, J
) ∼8.3 Hz), 4.02 (1H, dd, J ) 4.9 and 8.0 Hz), 4.65 and 4.75
(2H, ABq, J ) 11.7 Hz), 4.79 (1H, dd, J ) 4.9 and 10.3 Hz),
4.85 and 4.95 (2H, ABq, J ) 7.3 Hz), 6.52 (1H, s), and 7.25-

Enantiodivergent Synthesis of Mannostatin Analogues
J . Org. Chem., Vol. 61, No. 2, 1996 487
(1S,2S,3R,4R,5R)-2-O-Ben zyl-5-((ter t-bu toxyca r bon yl)-
a m i n o )-3,4-O -i s o p r o p y li d e n e c y c lo p e n t a n e -1,2,3,4-
tetr ol (45). Procedures used were similar to those used for
the preparation of 32 from 31; the yield was 98%; [R]26D +16.1°
(c 0.45, CHCl3); NMR (CDCl3, 400 MHz) δ 1.32 (3H, s), 1.47
(12H, s), 2.20 (1H, d, J ) 9.8 Hz), 3.90 (1H, s), 4.12 (1H, dd, J
) 4.4 and 9.8 Hz), 4.26 (1H, m), 4.5-4.65 (3H, m), 4.71 (1H, t,
J ) 5.4 Hz), 5.28 (1H, broad d, J ) 8.3 Hz), and 7.2-7.4 (5H,
m); mass spectrum (FAB+) m/ z (relative intensity) 380 (M +
H)+ (19), 280 (100), 91 (85), 57 (35).
THF (46.4 mL), H2O (15 µL) and H2SO4 (10 µL), and the
solution was stirred at room temperature overnight. After
being stirred with excess NaHCO3, the mixture was filtered
through a Celite. Evaporation of the filtrate gave an oil, which
was suspended in CH2Cl2 (2 mL). To a suspension was added
CH3SiI (37 µL, 0.2 µmol), and the mixture was stirred at room
temperature for 3 h. After addition of methanol, evaporation
of the solvent gave a solid. The solid was subjected to PTLC
on silica gel to give an amorphous solid of 51 (8 mg, 77%):
[R]23D +11° (c 0.2, CH3OH); NMR (CD3OD) δ 2.19 (3H, s), 2.75
(1H, dd, J ) 6.3 and 9.3 Hz), 3.63 (1H, dd, J ) 8.3 and 9.3
Hz), 3.94 (1H, dd, J ) 4.9 and 8.3 Hz), 4.02 (1H, dd, J ) 6.3
and 9.3 Hz), and 4.66 (1H, dd, J ) 4.9 and 9.3 Hz); mas
spectrum (FAB+) m/ z (relative intensity) 228 (M + Na)+ (22),
206 (M + H)+ (80), 176 (100), 107 (73), 89 (62).
(3a R ,3b S ,6a R ,7R ,7a R )-7-Be n zoxy-2,2-d im e t h yl[1,3]-
d ioxolo[4,5-a ]cyclop en t[4,5-d ]oxa zolid en -5-on e (46). Pro-
cedures used were similar to those used for the preparation
of 33 from 32; the yield was 64%: mp 137-138 °C; [R]27
D
+47.1° (c 0.45, CHCl3); NMR (CDCl3, 400 MHz) δ 1.34 and
1.50 (each 3H, s), 4.21 (1H, d, J ) 6.8 Hz), 4.24 (1H, broad s),
4.64 (2H, s), 4.66 (1H, d, J ) 5.6 Hz), 4.71 (1H, d, J ) 5.6 Hz),
4.94 (1H, d, J ) 6.8 Hz), 5.00 (1H, broad s), and 7.2-7.4 (5H,
m); mass spectrum (FAB+) m/ z (relative intensity) 306 (M +
H)+ (100), 137 (36), 91 (88). Anal. Calcd for C16H19NO5: C,
62.94; H, 6.27; N, 4.59. Found: C, 62.65; H, 6.48; N, 4.73.
(3a S,4R,5S,6R,6a S)-4,6-Dih yd r oxy-5-(m et h ylt h io)cy-
clop en t[d ]oxa zolid in -2-on e (52). Procedures used were
similar to those used for the preparation of 51 from 49; the
yield was 70%; [R]23 -71° (c 0.27, CH3OH); NMR (CD3OD,
D
400 MHz) δ 2.20 (3H, s), 2.89 (1H, dd, J ) 3.9 and 10.3 Hz),
4.06 (1H, d, J ) 3.9 Hz), 4.09 (1H, dd, J ) 5.9 and 10.3 Hz),
4.25 (1H, dd, J ) 5.9 and 7.8 Hz), and 4.73 (1H, d, J ) 7.8
Hz); 13C NMR (CD3OD) δ 14.97, 54.82, 58.44, 75.15, 77.02,
84.26 and 161.47; mass spectrum (FAB+) m/ z (relative inten-
sity) 228 (M + Na)+ (40), 206 (M + H)+ (100), 176 (80), 107
(41).
(3aS,4S,5R,6R,6aS)-6-Ben zoxy-4,5-dih ydr oxycyclopen t-
[d ]oxa zolid in -2-on e (47). Procedures used were similar to
those used for the preparation of 35 from 34; the yield was
72%; crystallized from ethyl acetate-methanol (5:1): mp 178-
179 °C; [R]27 +3.5° (c 0.5, CHCl3); NMR (CD3OD, 400 MHz)
D
2-Ep im a n n osta tin A Hyd r och lor id e (12). Compound 37
(13 mg, 0.04 mmol) was dissolved in a solution (2 mL) of water
(10 mL) containing Ba(OH)2‚8H2O (100 mg, 0.32 mmol), and
the solution was stirred at 100 °C for 1 h. After introduction
of CO2 gas, the resulting precipitates were filtered off. Evapo-
ration of the filtrate gave a foam. The foam was dissolved in
4 M HCl-dioxane (0.5 mL), and the mixture was stirred at
room temperature for 4 h. The resulting precipitates were
taken by centrifugation and washed thoroughly with ether to
give a colorless amorphous solid of hydrochloride of 12 (8 mg,
δ 3.97 (1H, dd, J ) 4.3 and 5.4 Hz), 4.02 (1H, t, J ) 4.3 Hz),
4.04 (1H, dd, J ) 2.0 and 5.4 Hz), 4.18 (1H, dd, J ) 4.3 and
8.6 Hz), 4.62 and 4.69 (2H, ABq, J ) 11.7 Hz), 4.81 (1H, dd, J
) 2.0 and 8.5 Hz), and 7.25-7.45 (5H, m); mass sepctrum
(FAB+) m/ z (relative intensity) 266 (M + H)+ (35), 120 (100),
107 (93), 91 (93), 90 (83), 77 (86). Anal. Calcd for C13H15NO5:
C, 58.86; H, 5.70; N, 5.28. Found: C, 58.57; H, 5.83; N, 5.39.
(3a R,3bR,6a S,7R,7a S)-7-Ben zoxy[1,3,2]d ioxa th iolo[4,5-
a ]cyclop en t [4,5-d ]oxa zolid in -2,2,5-t r ion e (48). Proce-
dures used were similar to those used for the preparation of
36 from 35; the yield was 89%; crystallized from ethanol; mp
150-151 °C; [R]23D +46.6° (c 0.57, CH3OH); NMR (CD3OD, 400
MHz) δ 4.45 (1H, broad t, J ) 2.0 Hz), 4.65 (1H, dd, J ) 5.9
and 7.8 Hz), 4.71 (2H, s), 5.06 (1H, dt, J ) 1.0 and 7.8 Hz),
5.40 (1H, dd, J ) 2.0 and 5.9 Hz), 5.45 (1H, t, J ) 5.9 Hz),
and 7.25-7.45 (5H, m); mass spectrum (FAB+) m/ z (relative
intensity) 328 (M + H)+ (83), 107 (99), 91 (100), 89 (71), 77
(71).
97%): mp 149-151 °C dec; [R]26 +16° (c 0.27, H2O); H NMR
D
(D2O, 400 MHz) δ 1.56 (3H, s), 2.28 (1H, t, J ) 9.3 Hz), 2.83
(1H, dd, J ) 6.8 and 9.3 Hz), 3.18 (1H, dd, J ) 6.8 and 9.3
Hz), 3.29 (1H, dd, J ) 4.9 and 6.8 Hz), and 3.45 (1H, dd, J )
4.9 and 6.8 Hz); mass spectrum (FAB+) m/ z (relative intensity)
180 (M + H)+ (100), 115 (57), 75 (83).
(1S,2R,3R,4S,5R)-3-Am in o-5-(m eth ylth io)cyclopen tan e-
1,2,4-tr iol Hyd r och lor id e (14). Compound 38 (15 mg, 0.046
mmol) was dissolved in a solution (2 mL) of water (10 mL)
containing Ba(OH)2‚8H2O (100 mg, 0.32 mmol), and the
solution was stirred at 100 °C for 1 h. After introduction of
CO2 gas, the resulting precipitates were filtered off. Evapora-
tion of the filtrate gave a foam. The foam was dissolved in 4
M HCl-dioxane (0.5 mL), and the mixture was stirred at room
temperature for 4 h. Evaporation of the solvent gave an oil,
which was washed thoroughly with ether to give a viscous
solid. The resulting viscous solid was subjected to column
chromatography on Diaion HP-20 (Nippon Rensui Co.). Elu-
tion with water gave a hygroscopic amorphous solid of hydro-
(3a R,4S,5S,6R,6a S)-6-Ben zoxy-4-(m et h ylt h io)-5-(su l-
fooxy)cyclop en t [d ]oxa zolid in -2-on e (49) a n d (3a S,4R,-
5R,6R,6a R)-6-Ben zoxy-5-(m eth ylth io)-4-(su lfooxy)cyclo-
p en t[d ]oxa zolid in -2-on e (50). A mixture of 48 (49 mg, 0.15
mmol) and NaSCH3 (53 mg, 0.76 mmol) in dry DMF (0.5 mL)
was stirred under argon at room temperature for 1 h. Evapo-
ration of the solvent gave a viscous solid, which was dissolved
in CHCl3. The solution was washed with saturated aqueous
NaCl solution, dried over MgSO4, and filtered. Evaporation
of the filtrate gave a foam. The foam was subjected to PTLC
on silica gel developed with chloroform-methanol to give a
foam of 49 (26 mg, 46%) and a foam of 50 (25 mg, 44%).
chloride of 14 (8 mg, 84%): [R]26 +36.4° (c 0.53, H2O); NMR
D
(D2O, 400 MHz) δ 2.04 (3H, s), 3.13 (1H, t, J ) 5.4 Hz), 3.73
(1H, t, J ) 6.6 Hz), and 4.0-4.2 (3H, m); mass spectrum
(FAB+) m/ z (relative intensity) 180 (M + H)+ (100), 115 (99),
75 (56).
49: [R]22 +20.3° (c 1.7, CH3OH); NMR (CD3OD, 400 MHz)
D
δ 2.23 (3H, s), 3.39 (1H, m), 4.29 (1H, m), 4.32 (1H, dd, J )
1.9 and 7.8 Hz), 4.62 and 4.75 (2H, ABq, J ) 11.7 Hz), 4.92
(1H, m), 5.00 (1H, d with a small coupling, J ) 7.8 Hz), and
7.20-7.45 (5H, m); 13C NMR (CD3OD) δ 15.89, 57.66, 63.93,
73.39, 85.28, 86.38, 88.87, 160.44; mass spectrum (FAB+) m/ z
(relative intensity) 398 (M+Na)+ (9), 176 (100), 107 (57), 87
(48).
2-Ep im a n n osta tin A En a n tiom er (13). Compound 51 (6
mg, 0.029 mmol) was dissolved in a solution (1 mL) of water
(10 mL) containing Ba(OH)2‚8H2O (100 mg, 0.32 mmol), and
the solution was stirred at 100 °C for 6 h. After introduction
of CO2 gas, the resulting precipitates were filtered off. Evapo-
ration of the filtrate gave a solid. The solid was subjected to
PTLC on silica gel developed with chloroform-methanol-
50: [R]22 -65.5° (c 2.0, CH3OH); NMR (CD3OD, 400 MHz)
D
δ 2.21 (3H, s), 3.17 (1H, dd, J ) 4.9 and 9.8 Hz), 3.99 (1H, d,
J ) 4.9 Hz), 4.56 (1H, dd, J ) 5.7 and 7.8 Hz), 4.61 and 4.69
(2H, ABq, J ) 12.0 Hz), 4.78 (1H, dd, J ) 5.7 and 9.8 Hz),
4.93 (1H, d, J ) 7.8 Hz), and 7.20-7.40 (5H, m); 13C NMR
(CD3OD) δ 15.18, 51.87, 57.21, 73.40, 81.61, 83.14, 83.45,
160.94; mass spectrum (FAB-) m/ z (relative intensity) 374 (M
- H)- (100), 306 (39), 199 (30), 153 (94).
ammonia (2:1:0.3) to give 13 (3 mg, 57%): [R]24 -11° (c 0.1,
D
H2O); NMR (D2O, 400 MHz) δ 2.00 (3H, s), 2.52 (1H, t, J )
9.0 Hz), 2.99 (1H, dd, J ) 6.8 and 9.2 Hz), 3.57 (1H, dd, J )
6.3 and 8.8 Hz), 3.68 (1H, dd, J ) 4.9 and 6.3 Hz), and 3.76
(1H, dd, J ) 4.9 and 6.8 Hz); mass spectrum (FAB+) m/ z 180
(M + H)+ (92), 115 (100), 75 (91).
(3a R,4S,5S,6S,6a S)-5,6-Dih yd r oxy-4-(m eth ylth io)cyclo-
p en t[d ]oxa zolid in -2-on e (51). Compound 49 (19 mg, 0.05
mmol) was dissolved in a solution (0.5 mL) of a mixture of
(1R,2S,3R,4R,5S)-3-Am in o-5-(m eth ylth io)cyclopen tan e-
1,2,4-tr iol (15). Procedures used were similar to those used
for the preparation of 14 from 51 described above; the yield

488 J . Org. Chem., Vol. 61, No. 2, 1996
Nishimura et al.
was 61%: [R]24D -30.8° (c 0.14, H2O); NMR (D2O, 500 MHz) δ
2.19 (3H, s), 3.24 (1H, t, J ) 6.4 Hz), 3.48 (1H, dd, J ) 5.4 and
6.5 Hz), 4.02 (1H, dd, J ) 3.9 and 5.4 Hz), 4.03 (1H, t, J ) 6.4
Hz), and 4.20 (1H, dd, J ) 3.9 and 6.4 Hz); 13C NMR (D2O) δ
14.05, 53.37, 55.14, 74.40, 75.42 and 76.52; mass spectrum
(FAB+) m/ z (relative intensity) 180 (M + H)+ (54), 115 (100),
75 (38).
Rigaku AFC7R diffractometer with graphite-monochromated
Cu KR radiation giving 1172 unique reflections. The structure
was solved by a direct method (SHEL XS86) to yield R ) 0.050
for 896 independent reflections with I > 2σ(I).27
Ack n ow led gm en t. We are grateful to Dr. S. Ohuchi
of the Pharmaceutical Research Center, Meiji Seika
Kaisha, Ltd., and Dr. C. Imada of Institute of Microbial
Chemistry for the biological evaluation of the deriva-
tives. We also thank Ms. R. Shinei and Y. Fukurose
for their technical assistance.
Molecu la r Mod elin g of 13. Force field calculation MM228
and semiempirical calculation PM3 incorporated in the MO-
PAC (ver. 6.0)29 package were performed on BIOCES[E]30
system in one high performance desk top workstation (NEC
EWS 4800/330).
X-r a y An a lysis of 47. Crystal data: C13H15NO5, orthor-
hombic P212121, a ) 7.198(2) Å, b ) 29.587(3) Å, c ) 5.971(2)
Å, V ) 1271.6(5) Å, Z ) 4. Data were collected at 20 °C on a
Su p p or tin g In for m a tion Ava ila ble: 1H NMR, 13C NMR,
and HMBC spectra of compounds 12-15 and 20-52 (80
pages). This material is contained in libraries on microfiche,
immediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
masthead page for ordering information.
(28) Allinger, N. L. J . Am. Chem. Soc. 1977, 99, 8127.
(29) Stewart, J . J . P. J . Comput. Chem. 1989, 10, 209. MOPAC Ver.
6, J . J . P. Stewart, QCPE Bull. 1989, 9, 10; Revised as Ver. 6.01 by T.
Hirano, University of Tokyo, for HITAC and UNIX Machines, J CPE
Newsletter 1989, 1, 10.
(30) BIOCES[E]: supporting system for protein modeling and
molecular design by NEC, J apan.
J O951126V