Acidic and basic hydrolysis of an optically pure spiro-λ4-sulfurane: Completely opposite stereochemical outcome [7]

Full text of DOI:10.1021/ja973039l

J. Am. Chem. Soc. 1998, 120, 1631-1632
1631
Scheme 1
Acidic and Basic Hydrolysis of an Optically Pure
Spiro-λ4-sulfurane: Completely Opposite
Stereochemical Outcome
Jian Zhang, Shinichi Saito, and Toru Koizumi*,†
Faculty of Pharmaceutical Sciences
Toyama Medical & Pharmaceutical UniVersity
2630 Sugitani, Toyama 930-01, Japan
ReceiVed August 29, 1997
Sulfurane (1) has been proposed as an intermediate in various
reactions of organosulfur compounds.1 A number of achiral
sulfuranes have been prepared, and the structural as well as the
chemical properties were investigated.2 However, the stereo-
chemistry of chiral sulfuranes and stereochemical process of their
reactions have been scarcely studied.3,4 We designed a series of
chiral alkoxyacyloxyspirosulfuranes using the 2-exo-hydroxy-10-
bornyl group as a chiral ligand to study the stereochemistry of
sulfuranes and their reactions. Herein we report the synthesis,
structural determination and the mechanistic research on the
hydrolysis of optically pure spirosulfuranes.
We synthesized the chiral spiro-λ4-sulfuranes (3a-e) as il-
lustrated in Scheme 1.5 Spirosulfuranes (3a-d) were obtained
as colorless crystals in high yield and as single diastereomers.
An X-ray crystallographic analysis of 3a indicated that the
spirosulfuranes have a slightly distorted trigonal bipyramidal
(TBP) structure as shown in Figure 1.6
Figure 1. ORTEP drawings of the compounds 3a, 4, and 5 with 50%
thermal ellipsoids.
To give a deep insight into the stereochemistry of the
nucleophilic reactions of hypervalent sulfur compounds and how
the coordinated groups bound to the sulfur atom affect this
process, we carried out the hydrolysis of spirosulfurane (3a) under
various conditions (Scheme 2 and Table 1). Compound 3a was
easily hydrolyzed under a basic condition (1 N NaOH) to give
optically pure sulfoxide (4) as a single diastereomer (Table 1,
Scheme 2
† Deceased, January 12, 1998.
(1) Martin, J. C.; Paul, I. C. Science 1976, 191, 154-159.
(2) (a) Kapovits, I.; Ka´lma´n, A. J. Chem. Soc., Chem. Commun. 1971, 649-
650. (b) Adzima, L. J.; Martin, J. C. J. Org. Chem. 1977, 42, 4006-4016. (c)
Kapovits, I.; Ra´bai, J.; Szabo´, D.; Czako´, K.; Kucsman, AÄ .; Argay, G.; Fu¨lo¨p,
V.; Ka´lma´n, A.; Koritsa´nszky, T.; Pa´rka´nyi, L. J. Chem. Soc., Perkin Trans.
2 1993, 847-853. (d) Vass, E.; Ruff, F.; Kapovits, I.; Ra´bai, J.; Szabo´, D. J.
Chem. Soc., Perkin Trans. 2 1993, 855-859. (e) Hornbuckle, S. F.; Livant,
P.; Webb, T. R. J. Org. Chem. 1995, 60, 4153-4159. (f) Rabai, J.; Kapovits,
I.; Argay, G.; Koritsanszky, T.; Kalman, A. J. Chem. Soc., Chem. Commun.
1995, 1069-1070. (g) Szabo´, D.; Kapovits, I.; Argay, G.; Czugler, M.;
Ka´lma´n, A.; Koritsa´nszky, T. J. Chem. Soc., Perkin Trans. 2 1997, 1045-
1053.
(3) (a) Huszthy, P.; Kapovits, I.; Kucsman, AÄ .; Radics, L. Tetrahedron
Lett. 1978, 1853-1856. (b) Allenmark, S.; Claeson, S. Tetrahedron: Asym-
metry 1993, 4, 2329-2332. (c) Drabowicz, J.; Martin, J. C. Tetrahedron:
Asymmetry 1993, 4, 297-300. (d) Drabowicz, J.; Martin, J. C. Pure Appl.
Chem. 1996, 68, 951-956. (e) Szabo´, D.; Szendeffy, S.; Kapovits, I.; Kucsman,
AÄ .; Czugler, M.; Ka´lma´n, A.; Nagy, P. Tetrahedron: Asymmetry 1997, 8,
2411-2420.
entry 1). The (R) absolute configuration of the sulfur atom in
sulfoxide (4) has been determined by an X-ray analysis (Figure
1).7 In contrast, hydrolysis of spirosulfurane (3a) under an acidic
condition (1 N HCl) gaVe sulfoxide (5), also as a single
diastereomer but with an opposite absolute configuration at the
sulfur atom (Table 1, entry 2). The stereochemistry of sulfoxide
(5) was also clearly determined by an X-ray analysis (Figure 1).8
Next, we confirmed that the sulfoxides did not isomerize under
the conditions employed for the hydrolysis. Stirring the sulfoxides
(4 or 5) under basic or acidic conditions afforded only the starting
materials (Table 1, entries 3-6).8 These results clearly rule out
the possibility of pH-dependent isomerization of these sulfoxides,
and we, therefore, conclude that the chiral sulfoxides obtained
here are stereoselectively formed by the hydrolysis.
(4) Zhang, J.; Takahashi, T.; Koizumi, T. Heterocycles 1997, 44, 325-
339, and references therein.
(5) See Supporting Information for detailed procedures. The structure of
sulfurane (3e) was determined by the 1H NMR analysis of the crude product
since it is not stable to moisture.
(6) Crystal data for 3a: C17H20SO3, colorless crystal, MW ) 304.40,
orthorhombic, space group P212121 (#19) with a ) 11.206(3) Å, b ) 12.282-
(2) Å, c ) 10.965(3) Å, V ) 1509.1(5) Å3, Z ) 4, density(calcd) ) 1.34 g
cm-3, F(000) ) 648.00, λ ) 0.710 69 Å, T ) 293 K, µ (Mo KR) ) 2.22
cm-1. Intensity data were collected on a Rigaku AFC7R diffractometer using
a 0.15 × 0.15 × 0.20 mm3 sized crystal. 1999 unique reflections; 766 with I
> 3.00σ(I) were used in refinement; R ) 4.2%, Rw ) 4.4%.
S0002-7863(97)03039-4 CCC: $15.00 © 1998 American Chemical Society
Published on Web 02/06/1998

1632 J. Am. Chem. Soc., Vol. 120, No. 7, 1998
Communications to the Editor
Table 1. The Reaction of 3a, 4, and 5 under Basic or Acidic
Conditions
Scheme 3
entry substrate
condition
producta yield (%)
1
2
3
4
5
6
3a
3a
4
4
5
1 N NaOH, 0 °C, 0.5 h
1 N HCl, rt,b 48 h
1 N NaOH, rt,b 48 h
1 N HCl, rt,b 48 h
1 N NaOH, rt,b 48 h
1 N HCl, rt,b 48 h
4
5
4
4
5
5
88
98
92
98
96
98
5
a No isomer was detected by an 1H NMR analysis. b Room temper-
ature ) rt.
Finally, we performed the hydrolysis of spirosulfurane (3a)
with isotopically labeled H2O to see whether and where the
oxygen atom of H2O attack the spirosulfurane. Spirosulfurane
(3a) was hydrolyzed under basic or acidic conditions in the
presence of H218O (97 atom % 18O) followed by treatment with
diazomethane to give methyl esters 6-18O and 7-18O.9 Mass
spectroscopic analyses revealed that 6-18O and 7-18O are enriched
with 18O to a significant extent (70% and 91% incorporation,
respectively).9 On the other hand, the sulfoxides (4-17O and
5-17O) obtained by hydrolysis of 3a with H217O (20.3 atom %
17O) under basic or acidic conditions showed signals with chemical
shift of -9.2 and -8.1 ppm in their 17O NMR spectra,
respectively. The values of the chemical shift strongly indicate
that under both conditions the oxygen atoms from H217O were
bound to the sulfur atoms.10 Based on these results, we concluded
that the oxygen of H2O attacked sulfur atom directly in the
hydrolysis.
We propose the mechanism of these reactions as follows:
hydrolysis under basic condition may proceed through the attack
of hydroxide ion onto the central sulfur atom to give an
intermediate (8) (Scheme 3).11 Cleavage of S-O (acyloxy) bond12
and isomerization around the sulfur center generates the penta-
coordinate intermediate (9) with the hydroxyl group at the apical
position.13 Then, deprotonation and tandem breaking of the S-O
(alkoxy) bond takes place to give the highly diastereoselective
formation of the sulfoxide (4) with R absolute configuration.
Scheme 4
Under the acidic condition, the reaction may proceed through the
initial protonation of the spirosulfurane at the oxygen of alkoxy,14
then attack of H2O to the sulfur atom takes place, and a
hexacoordinate sulfur intermediate (11) is formed (Scheme 4).
Cleavage of the S-O (alkoxy) bond of the intermediate (11) and
isomerization around the sulfur center produce an intermediate
(12) with the hydroxyl group at the apical position.13 Final
deprotonation and consecutive breaking of the S-O (acyloxy)
bond gave sulfoxide (5) with S absolute configuration at the sulfur
atom.15
In summary, an optically pure sulfurane (3a) was stereoselec-
tively hydrolyzed under basic and acidic conditions to give the
sulfoxides (4 and 5) with the completely opposite absolute
configuration at sulfur atom. We proposed the mechanism of
the reaction which accounts for the observed stereochemical
outcome. The results obtained here would be helpful for the
understanding of the stereochemistry of the nucleophilic reaction
concerning the hypervalent compounds.
(7) Crystal data for 4: C17H22SO4, colorless crystal, MW ) 322.42,
orthorhombic, space group P212121 (#19) with a ) 13.124(3) Å, b ) 14.720-
(3) Å, c ) 8.659(2) Å, V ) 1672.8(5) Å3, Z ) 4, density(calcd) ) 1.280 g
cm-3, F(000) ) 688.00, λ ) 0.710 69 Å, T ) 293 K, µ (Mo KR) ) 2.08 cm
cm-1. Intensity data were collected on a Rigaku AFC7R diffractometer using
a 0.20 × 0.20 × 0.25 mm3 sized crystal. 2216 unique reflections; 1464 with
I > 3.00σ(I) were used in refinement; R ) 4.2%, Rw ) 4.1%. Crystal data for
5: C17H22SO4, colorless crystal, MW ) 322.42, monoclinic, space group P21
(#4) with a ) 6.961(4) Å, b ) 10.993(3) Å, c ) 10.765(4) Å, â ) 103.04-
(4)°, V ) 802.6(6) Å3, Z ) 2, density(calcd) ) 1.334 g cm-3, F(000) ) 344.00,
λ ) 0.710 69 Å, T ) 293 K, µ (Mo KR) ) 2.17 cm-1. Intensity data were
collected on a Rigaku AFC7R diffractometer using a 0.30 × 0.20 × 0.20
mm3 sized crystal. 2084 unique reflections; 1138 with I > 3.00σ(I) were used
in refinement; R ) 4.1%, Rw ) 4.2%.
Acknowledgment. This work was supported by Grants-in-Aid for
Scientific Research from the Ministry of Education, Sciences, Sports and
Culture, Japan No. 09470483 (T.K.), No. 092338213 (T.K.), No.
09239219 (T.K.), by Hoan Sha Foundation (T.K.), and by Uehara
Memorial Foundation (T.K.).
(8) Refluxing the sulfoxides (4 or 5) under basic condition for 5 h gave
also the starting material recovered. Slight isomerization was observed when
the sulfoxides (4 or 5) were refluxed in 1 N HCl-EtOH.
(9) Esterification was necessary in order to observe the mass spectra. The
isotopic purity is calculated by comparing the height of peaks at m/z ) 186
Supporting Information Available: Detailed synthetic procedures
and spectroscopic data for sulfides and compounds 3a-e, 4, 5, 6, and 7
and structure determination summary and listings of final atomic
coordinates, thermal parameters, bond lengths, and bond angles for
compounds 3a, 4, and 5 (67 pages). See any current masthead page for
ordering and Web access instructions.
[(M+- 18O) - C10H16O] with that of peaks at m/z ) 184 [(M+
-
16O) -
C10H16O] in the mass spectra of sulfoxides (6-18O or 7-18O), while in the
mass spectra of sulfoxides (6-16O or 7-16O) there are no peaks at m/z ) 186.
(10) (a) Boykin, D. W.; Baumstark, A. L. Tetrahedron 1989, 45, 3613-
3651. (b) Dyer, J. C.; Harris, D. C.; Evans, J. S. A. J. Org. Chem. 1982, 47,
3660-3664.
JA973039L
(11) Martin, J. C.; Balthazor, T. M. J. Am Chem. Soc. 1977, 99, 152-162.
(12) The S-O (acyloxy) bond is expected to be hydrolyzed easier compared
to the S-O (alkoxy) bond. See: Lam, W. Y.; Duesler, E. N.; Martin, J. C. J.
Am. Chem. Soc. 1981, 103, 127-135.
(13) The pentacoordinated intermediates (9 and 12) can be reasonably
considered as with the TBP geometries and the most electronegative groups
in 9 and 12 are expected to occupy axial positions.
(14) The basicity of ethers (pKBH+ ) -3.5) is generally stronger than that
of esters (pKBH+ ) -6.5). March, J. AdVanced Organic Chemistry: Reactions,
Mechanisms, and Structure; Wiley-Interscience: New York, 1992; p 250.
(15) Alternatively, the cleavage of the S-O (alkoxy) bond may be induced
by the initial protonation to give a sulfonium cation, then the attack of water
onto the sulfur atom from pseudoaxial direction may afford the intermediate
(12).