Oxidation of tetrathiolanes: Isolation of a vic-disulfoxide, 5-(1-adamantyl)-5-tert-butyltetrathiolane 2,3-dioxide and its decomposition to the dithiirane 1-oxide and 'S2O'

Article abstract of DOI:10.1016/S0022-328X(00)00435-6

Oxidation of 5-(1-adamantyl)-5-tert-butyltetrathiolane (3a) with dimethyldioxirane (DMD) at -78 or -20°C gave (1R*,3S*)-and (1R*,3R*)-3-(1-adamantyl)-3-tert-butyldithiirane 1-oxides (cis-4a and trans-4a, respectively) as the final products. The reaction was revealed to proceed through stepwise oxidation to the corresponding 2-oxide and then to the 2,3-dioxide 5, a vic-disulfoxide; the latter is isolated in pure form by low-temperature recrystallization and is fairly stable at room temperature in the crystalline state. The structure of 5 was determined by X-ray crystallography. The 2,3-oxide 5 decomposes in solution above -10°C to cis-4a, trans-4a, and 'S₂O' as the principal products. The reactive sulfur species, S₂O, is trapped by 2,3-dimethyl-1,3-butadiene to give 4,5-dimethyl-3H,6H-1,2-dithiin 1-oxide. In the absence of the diene, S₂O disproportionates to SO₂ and 'S₃', which is trapped by norbornene to give exo-norbornane trithiolane (exo-3,4,5-trithiatricyclo[5.2.1.0^2,6]decane).

Full text of DOI:10.1016/S0022-328X(00)00435-6

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 611 (2000) 127–135
Oxidation of tetrathiolanes: isolation of a 6ic-disulfoxide,
5-(1-adamantyl)-5-tert-butyltetrathiolane 2,3-dioxide and its
decomposition to the dithiirane 1-oxide and ‘S2O’
Akihiko Ishii *1, Masaaki Nakabayashi, Yi-Nan Jin, Juzo Nakayama *2
Department of Chemistry, Faculty of Science, Saitama Uni6ersity, Urawa, Saitama 338-8570, Japan
Received 1 March 2000; accepted 31 March 2000
Abstract
Oxidation of 5-(1-adamantyl)-5-tert-butyltetrathiolane (3a) with dimethyldioxirane (DMD) at −78 or −20°C gave (1R*,3S*)-
and (1R*,3R*)-3-(1-adamantyl)-3-tert-butyldithiirane 1-oxides (cis-4a and trans-4a, respectively) as the final products. The
reaction was revealed to proceed through stepwise oxidation to the corresponding 2-oxide and then to the 2,3-dioxide 5, a
6ic-disulfoxide; the latter is isolated in pure form by low-temperature recrystallization and is fairly stable at room temperature in
the crystalline state. The structure of 5 was determined by X-ray crystallography. The 2,3-oxide 5 decomposes in solution above
−10°C to cis-4a, trans-4a, and ‘S2O’ as the principal products. The reactive sulfur species, S2O, is trapped by 2,3-dimethyl-1,3-bu-
tadiene to give 4,5-dimethyl-3H,6H-1,2-dithiin 1-oxide. In the absence of the diene, S2O disproportionates to SO2 and ‘S3’, which
is trapped by norbornene to give exo-norbornane trithiolane (exo-3,4,5-trithiatricyclo[5.2.1.02,6]decane). © 2000 Elsevier Science
S.A. All rights reserved.
Keywords: Tetrathiolane; Oxidation; Dimethyldioxirane; 6ic-Disulfoxide; Dithiirane oxide; S2O; S3
1. Introduction
(DMD) leads to a new synthesis of dithiirane 1-oxides
4 [3].
We have reported the first synthesis of isolable dithi-
iranes 2 by the oxidative hydrolysis of bicyclic 1,3-dithi-
etanes 1 [1]. Detailed examination of this synthesis has
revealed it to be successfully applicable only to bicyclic
1,3-dithietanes, which inevitably yield carbonyl group-
containing dithiiranes 2 [1d,e]. Although the carbonyl
groups are considered to be independent of the stability
of the dithiirane rings by inspection of the crystal
structures of 2 (n=1, m=0,1) [1a,b,e], they take part
in some reactions of 2 [1b,e,f]. In our continuing study
to develop new and more general methods for the
preparation of dithiirane derivatives, which do not pos-
sess other functional groups, we found that the oxida-
tion of tetrathiolanes 3 [2] with dimethyldioxirane
Furthermore, we succeeded in the isolation of the
corresponding tetrathiolane 2,3-dioxide 5 (Fig. 1), the
first isolable 6ic-disulfoxide [4], as the intermediate
giving 4a. 6ic-Disulfoxides (a-disulfoxides), which pos-
sess an extremely weak sulfurꢀsulfur bond, are an im-
portant intermediate in the oxidation of oligosulfides
and have been drawing considerable attention [5–7].
Nevertheless, most of them are still elusive and only a
few were detected by NMR spectroscopy [7].
1 *Corresponding author.
2 *Corresponding author. Tel.: +81-48-8583390; fax: +81-48-
8583700; e-mail: nakaj@post.saitama-u.ac.jp.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00435-6

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A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
We report here a full account of the oxidation of
compared with that given in our preliminary report [4].
The cis–trans mixture of 4a was separated by HPLC
with a silica-gel column to give cis-4a and trans-4a in
28 and 24% isolated yields, respectively (Eq. (1)). Their
tetrathiolanes 3 with DMD including the structure
determination of intermediates, mono- and dioxides of
3, and decomposition of the 2,3-dioxide 5 to the
dithiirane 1-oxide 4 and a reactive sulfur species, S2O.
1
stereochemistry could be elucidated by H-NMR spec-
troscopy: the tert-butyl signal of cis-4a (l 1.09) appears
at a 0.35 ppm higher field than that of trans-4a (l 1.44),
whereas three broad signals due to the adamantyl of
cis-4a appear at 0.08–0.23 ppm lower fields than those
of trans-4a, because of the anisotropy of the SO group
[9]. The above assignment was further supported by
aromatic solvent-induced shift studies [10]. Optical res-
olution of (1R*,3R*)-4a (trans-4a) was performed by
HPLC equipped with a chiral column, and the enan-
tiomer with a shorter retention time was assigned as
(1R, 3R)-4a by X-ray crystallography [11].
2. Results and discussion
2.1. Oxidation of tetrathiolane 3a with DMD:
formation of dithiirane 1-oxide 4a
A solution of 1-adamantyl-tert-butyltetrathiolane
(3a) in dichloromethane was treated with DMD [8]
(four molar equivalents) at −78°C, and the mixture
was stirred for 1 h at −78°C and then for 4 h at room
temperature. Removal of the solvent and careful purifi-
cation of the residue by gel-permeation chromatogra-
phy (GPC) gave
a mixture of (1R*,3S*)- and
(1)
(1R*,3R*)-dithiirane 1-oxides 4a (cis-4a and trans-4a,
respectively) in 62% combined yield. The use of the
optimized equivalent of DMD improved the yield of 4a
The dithiirane 1-oxides 4a decomposed at each melt-
ing point to give the corresponding thioketone S-oxides
(sulfines) 6a, thioketone 7a, and ketone 8. In solution,
thermal isomerization between cis-4a and trans-4a took
place in addition to decomposition. Thus, heating pure
cis-4a in CDCl3 at 60°C for 20 h yielded a mixture of
cis-4a (36%), trans-4a (21%), (E)-6a (10%), (Z)-6a
(11%), 7a (2%), and 8 (20%) (Eq. (2)). A similar result
was obtained by heating trans-4a in CDCl3.
(2)
The desulfurization of cis-4a and trans-4a by Ph3P
gave (Z)-6a and (E)-6a, respectively, in quantitative
yields with complete retention of configuration [12]
(Eqs. (3) and (4)).
(3)
(4)
Fig. 1. ORTEP drawing of (2R*,3R*)-5-(1-adamantyl)-5-tert-butylte-
trathiolane 2,3-dioxide (5) (ellipsoids at 50% probability). Relevant
2.2. Determination of the precursor of dithiirane
1-oxides 4
,
bond lengths (A) and bond angles (°): C1ꢀS1, 1.868(2); S1ꢀS2, 2.054;
S2ꢀS3, 2.301(1); S3ꢀS4, 2.052(1); S4ꢀC1, 1.861(2); C1ꢀC2, 1.606(3);
C1ꢀC3, 1.599(3); S2ꢀO1, 1.461(2); S3ꢀO2, 1.409(2); C1ꢀS1ꢀS2,
109.3(1); S1ꢀS2ꢀS3, 94.4(1); S2ꢀS3ꢀS4, 93.0(1); C1ꢀS4ꢀS3, 109.6(1);
S1ꢀC1ꢀS4, 107.8(1); C1ꢀS1ꢀS2ꢀS3, 39.6(1); S1ꢀS2ꢀS3ꢀS4, 45.5(1);
S2ꢀS3ꢀS4ꢀC1, 42.6(1).
2.2.1. NMR study
After the treatment of tetrathiolane 3a with DMD
(four molar equivalents) at −20°C, the solvent and

A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
129
Scheme 1.
Fig. 2.
disulfoxide of 3a. Meanwhile, based on the amount of
DMD used, the precursors (IV and V) of the thioke-
tone 7a are presumed to be two epimers of a monoox-
ide of 3a. The relationship among oxides of 3a and the
final products is thus summarized as shown in Scheme
1.
excess DMD were removed in 6acuo below −20°C,
and 13C-NMR spectra of the residue were measured in
a temperature range from −10°C to room tempera-
ture. At −10°C, three quaternary carbon peaks
assignable to the tetrathiolane carbon were observed at
l 154 (I), 118 (II), and 117 (III) in the peak–height
ratio of ca. 8:1:1.5. Raising of the temperature to room
temperature led to the gradual disappearance of these
peaks and, instead, the signals due to dithiirane 1-ox-
ides 4a appeared as the main ones along with those of
sulfines 6a, tetrathiolane 3a, and ketone 8 (Eq. (5)).
This observation strongly suggested that the compound
I is the main precursor of the dithiirane oxides 4a. The
tetrathiolane 3a was not observed in the 13C-NMR
spectrum at −10°C, indicating that 3a was formed by
a secondary reaction (vide infra).
2.2.2. Structure determination of tetrathiolane
2,3-dioxide 5 by X-ray crystallography
An X-ray analysis was performed on the disulfoxide
I to determine the regio- and stereochemistry, which
also provided important insight into the structure of the
monooxides IV and V. Recrystallization of the dioxide
I from a mixed solvent of dichloromethane and hexane
at −20°C led to the two polymorphic crystals; pale-
yellow plates (major, m.p. (dec) 74–76°C) and yellow
prisms (minor, m.p. (dec) 67–68°C), which are separa-
1
ble mechanically and gave the same H-NMR spectrum
at −10°C. X-ray crystallographic analyses on the two
crystals revealed that the disulfoxide I is the (2R*,3R*)-
2,3-dioxide 5 [13]. Fig. 2 depicts an ORTEP drawing of 5
obtained from a yellow prism (minor) with the relevant
bond lengths and bond angles. Both oxygen atoms in 5
occupy axial orientation and are trans to each other
with respect to the S(2)ꢀS(3) bond. The length of the
(5)
The oxidation of 3a with an equimolecular amount
of DMD provided interesting results. The 13C-NMR
spectrum of the reaction mixture at −20°C showed the
presence of alternative intermediates IV (lC 125.6) and
V (lC 125.7) with equal peak heights along with unre-
acted tetrathiolane 3a. The intermediates IV and V
decomposed on warming the mixture to room tempera-
ture, and the thioketone 7a appeared instead (Eq. (6)),
indicating that IV and V were precursors of 7a.
,
bond S(2)ꢀS(3) (2.301 A) is ca. 12% longer than that of
,
the corresponding SꢀS bond of 3a (2.052 A) [2a] and
the value is comparable to that of a calculated SꢀS
,
bond length of meso-MeS(O)S(O)Me (2.303 A) [14].
The pale-yellow plates (major) were disordered in the
crystals, and X-ray crystallographic analysis of the mix-
ture, which consisted of 86% of one enantiomer (2R,3R
or 2S,3S) and 14% of the other, led to unsatisfactory
results.
2.2.3. Structures of monooxides of 3
(6)
As a natural consequence, the structures of the
monooxides IV and V are assigned to the two epimeric
2-oxides (2R*,5R*)-8 and (2S*,5R*)-8. A possibility
that one of the two is the 1-oxide 9 could be ruled
out by the NMR study on the oxides of di-
(1-adamantyl)tetrathiolane 3b.
The compound I (lC 154), the precursor of dithiirane
1-oxides 4a, was isolated as pale yellow crystals by
recrystallization at low temperature. The compound I
was stable in the solid state even at room temperature
for several hours. The IR spectrum of I showed two
strong absorptions due to SꢁO stretching vibrations
(1109 and 1135 cm−1), and a result of the elemental
analysis indicated that the compound I is a dioxide of
3a. Thus, the compound I was determined to be a

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A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
The mono- and dioxides of 3b were prepared simi-
oxygen shift that leads to the rearrangement of 12 to 13
does not occur. As far as we know, such a 1,2-oxygen
shift in cyclic oligosulfides is not observed [17,18] or is
very slow [19] in solution at ambient temperature.
larly, and the 13C-NMR spectra were measured. In the
case of the monooxide of 3b, only one tetrathiolane
carbon was observed at lC 127.85 at −20°C, indicating
the formation of a single regioisomer as the monooxide
(10 or 11). The tetrathiolane carbon of a dioxide of 3b
appeared at lC 156.9. In addition, the two 1-adamantyl
groups of the dioxide are equivalent to each other
spectroscopically, indicating a C2-symmetrical struc-
ture, 12 or 13.
2.3. Decomposition of tetrathiolane 2,3-dioxide 5
The pure 2,3-dioxide 5 decomposed cleanly in solu-
tion above −10°C to cis-4a (53%), trans-4a (39%),
tetrathiolane 3a (8%) (1H-NMR), and elemental sulfur
(detected by TLC) (Eq. (7)).
(7)
The oxidation reactions of 3a and 3b with DMD
would proceed in similar regio- and stereoselectivities
because the 1-adamantyl and t-butyl groups have a
similar steric demand. Based on the confirmed structure
of the 2,3-dioxide 5, the dioxide of 3b is assigned to 12
and the monooxide to 10. Thus, monooxides IV and V
derived from 3a are also assigned to not regioisomers
but epimers of the monooxide 8. The sulfoxide group in
the monooxides, 8 and 10, would occupy axial orienta-
tion with respect to the tetrathiolane ring, because 3p
lone pair electrons on the sulfur atoms in 3 extend to
the axial direction of the tetrathiolane ring and, there-
fore, the axial attack of the less hindered 2-position by
electrophilic DMD is more favorable kinetically than
the equatorial one. In addition, the axial orientation of
the sulfoxide group is probably more stable thermody-
namically than the equatorial one owing to the
stereoelectronic effects of the lone pair electrons of the
adjacent sulfur atoms [15,16].
The decomposition of 5 obeyed the first-order kinet-
ics with a half-life of approximately 15 min at 25°C in
CDCl3 and the rate was independent of the concentra-
tion (Table 1, runs 1 and 2). The thermal stability of 5
in solution is much higher than that of acyclic 6ic-disul-
foxides, RS(O)S(O)R, studied by Freeman and Angele-
takis [7a–c], which could be observed below −40°C,
and is a little higher than or comparable to that of
bridged bicyclic 6ic-disulfoxides 14 [7d]. The dioxide 5
showed no tendency to rearrange to the OS-sulfenyl
sulfinate [RꢀS(O)OSꢀR] in contrast to the behavior of
other 6ic-disulfoxides [5a,d,6a,7]. Ring expansion by
rearrangement, from a five- to six-membered ring,
would result in widening of the S(1)ꢀC(1)ꢀS(4) angle
and narrowing of the C(2)ꢀC(1)ꢀC(3) angle at the same
time; the former deformation increases the unfavorable
steric interactions between the bulky substituents and
the neighboring sulfur atoms, and the latter also in-
creases the steric repulsion between the two bulky
substituents.
The above assignment on the regiochemistry of
mono- and dioxides of 3 is based on an assumption that
the regiochemistry of 5 in solution is the same as that in
the solid state, which means that, for example, a 1,2-
The counterpart of 4a that is formed by decomposi-
tion of 5 is most probably ‘S2O’. S2O is known to
disproportionate to SO2 and ‘S3’ [20]. S2O and S3 are
sulfur analogues of O3 and have been drawing much
attention in inorganic chemistry [21], coordination
chemistry [22], physical chemistry [23], computational
chemistry [24], and space science [25] but not in organic
chemistry [26,27]. Trapping experiments were done to
verify the formation of such interesting, small sulfur
species, S2O and S3. The results are summarized in
Scheme 2. Thus, 2,3-dioxide 5 was allowed to decom-
pose in the presence of 2,3-dimethyl-1,3-butadiene
(eight equivalents) at room temperature to give the
3H,6H-1,2-dithiin 1-oxide 15 in 87% yield along with
cis-4a (53%), trans-4a (33%), thioketone 7a (11%), and
Table 1
Kinetics on the decomposition of 5
Run
Additive
c
Temperature
(K)
k
(10−2 M)
(10−4 s−1
)
1
2
3
None
None
2,3-Dimethyl-
1,3-butadiene
Norbornene
2.75
0.40
3.75
297.590.3
297.390.5
297.790.1
6.83
6.22
6.40
4
2.63
297.590.6
5.98

A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
131
3. Conclusion
The oxidation of tetrathiolanes 3 with DMD pro-
vides the 2-oxides (8 and 10) initially and then the
2,3-dioxides (5 and 12). The structure of 5 was unam-
biguously determined by X-ray crystallography. The
tetrathiolane 2,3-dioxide, the first isolable 6ic-disulfox-
ide, is stable in the solid state for several hours at room
temperature but decomposes in solution to give the
dithiirane 1-oxides 4 and S2O, the latter of which
disproportionates to S3 and SO2 almost stoichiometri-
cally at ambient temperature (Scheme 3).
4. Experimental
Scheme 2.
Melting points were determined on a Mel-Temp cap-
illary tube apparatus and are uncorrected. 1H- (400
MHz) and 13C-NMR (100.6 MHz) spectra were deter-
mined on Bruker AM 400 and ARX400 spectrometers
using CDCl3 as the solvent unless otherwise noted. IR
spectra were taken on a Hitachi 270-50 spectrometer.
Mass spectra were determined on a JEOL JMS-DX303
spectrometer operating at 70 eV in the EI mode. Ele-
mental analyses were performed by the Chemical Anal-
ysis Center of Saitama University.
Scheme 3.
An acetone solution of dimethyldioxirane (DMD)
was prepared by the reported method and its concen-
tration was determined prior to use by oxidizing
thioanisole to its sulfoxide with this solution [8].
In worktop of the reactions, extracts were dried over
anhydrous MgSO4 after washing with water. Column
chromatography was performed with silica gel and
the eluent is given in parentheses. Gel permeation
chromatography (GPC) was performed on a Japan
Analytical Industry LC-908. High-pressure liquid
chromatography (HPLC) was performed with a packed
SiO2 column, INERTSIL PREP-SIL (10 mm i.d. 250
mm, GL Science INC.).
tetrathiolane 3a (3%). In contrast, the presence of nor-
bornene (ten equivalents) led to the formation of the
trithiolane 16 [28] in 85% yield along with cis-4a (50%),
trans-4a (38%), 7a (10%), and 3a (2%).
The formation of 15 and 16 can be explained as the
result of the reaction of 2,3-dimethyl-1,3-butadiene with
S2O [26] and that of norbornene with S3 [27], respec-
tively. The decomposition rate of 5 and yields of 4a
were independent of the presence of the trapping
reagents (Table 1, runs 3 and 4). The decomposition of
5 in the presence of both 2,3-dimethyl-1,3-butadiene
and norbornene furnished 15 overwhelmingly (72%) as
the trapping product. Therefore, we conclude that 5
splits into 4a and S2O (and 7a as a by-product) initially,
and the S2O reacts quickly with 2,3-dimethyl-1,3-buta-
diene in a [4+2] manner [26] to give 15, whereas the
reaction of S2O with norbornene does not take place or
is sluggish, allowing S2O to disproportionate to S3 and
SO2; the S3 thus formed reacts with norbornene effec-
tively to give 16. The reaction of S3 with the thioketone
7a also explains the formation of 3a (see Eqs. (5) and
(7)).
4.1. Preparation of thioketones 7
Di-1-adamantyl thioketone (7b) was prepared by the
reported method [31]. In a similar manner, 1-adamantyl
tert-butyl thioketone (7a) was prepared in 71% yield by
treatment of a solution of the corresponding ketone
hydrazone (1.468 g, 6.274 mmol) and Et3N (7.05 g, 69.7
mmol) in benzene (20 ml) with a solution of S2Cl2 (0.94
g, 6.963 mmol) in benzene (20 ml) at 0°C, followed by
usual aqueous worktop and chromatographic
purification.
Formation of the trithiolane 16 at elevated tempera-
tures [27–29] was reported previously in reactions of
norbornene with a reactive sulfur species, which were
unspecified or proposed to be S3 or S2. In the above
trapping experiments no adducts [30] between S2 and
2,3-dimethyl-1,3-butadiene were observed.
1
Di-1-adamantyl thioketone (7b). H-NMR: l 1.69–
1.72 (m, 12H), 2.06 (br s, 6H), 2.20 (pseudo d, J=2.9
Hz, 12H). 13C-NMR: l 29.2, 36.5, 43.5, 57.2, 279.3.
1-Adamantyl tert-butyl thioketone (7a). Purple
needles; m.p. 45–46°C (EtOH). 1H-NMR: l 1.45 (s,

132
A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
9H), 1.69–1.72 (m, 6H), 2.07 (br s, 3H), 2.18 (pseudo d,
J=2.9 Hz, 6H). 13C-NMR: l 29.2, 32.7, 36.5, 43.7,
53.9, 56.7, 279.0. MS m/z 236 [M+]. Anal. Calc. for
C15H24S: C, 76.21; H, 10.23. Found: C, 76.46; H,
10.44%.
HPLC to give cis-4a (22.5 mg, 28%) and trans-4a (19
mg, 24%).
4.4.2. One molar equi6alent of DMD
To a solution of 3a (25.2 mg, 0.076 mmol) in CH2Cl2
(5 ml) cooled at −78°C was added DMD in acetone
(0.08 M, 1 ml, 0.08 mmol). After stirring at −78°C for
5 h, the mixture was warmed to room temperature. The
solvent was removed under reduced pressure to give a
red solid. The residue was purified with GPC to afford
sulfines 6a (0.7 mg, 4%, Z:E=1:1), dithiirane 1-oxides
4a (6.6 mg, 31%, cis:trans=1.2:1), thioketone 7a (9.3
mg, 52%), and tetrathiolane 3a (1.8 mg, 7%).
4.2. Preparation of 5-(1-adamantyl)-5-tert-
butyltetrathiolane (3a)
Tetrathiolane 3a was prepared by the method re-
ported previously [2a] or by the reaction of the thioke-
tone 7a with S2Cl2: To a solution of 1-adamantyl
tert-butyl thioketone (7a) (400 mg, 1.7 mmol) in hexane
(80 ml) was added a solution of S2Cl2 (480 mg, 3.57
mmol) in hexane (20 ml) at 0°C. The mixture was
stirred for 1 h at 0°C and then for 1 h at room
temperature. The mixture was poured into ice–water
and extracted with ether. The extract was dried and the
filtrate was concentrated under reduced pressure. The
evaporation was stopped when an oily material just
appeared. The residue was passed through a short
column of silica gel (hexane) to give thioketone 7a and
a mixture of tetrathiolane 3a and elemental sulfur. The
mixture was further separated with GPC and the crude
product was recrystallized from dichloromethane–hex-
ane to give the tetrathiolane 3a (258 mg, 46%). Yellow
4.4.3. (1R*,3S*)-3-(1-Adamantyl)-3-tert-butyldithiirane
1-oxide (cis-4a)
1
Colorless solid; m.p. (dec) 106–107°C (EtOH). H-
NMR (CDCl3) l 1.09 (s, 9H), 1.69 (pseudo ABq, J=12
Hz, 6H), 2.05 (br s, 3H), 2.20 (br s, 6H); (C6D6) l 0.74
(s, 9H), 1.54 (pseudo d, J=11 Hz, 3H), 1.64 (pseudo d,
J=12 Hz, 3H), 1.92 (br s, 3H), 2.16 (br s, 6H).
13C-NMR: l 29.4, 29.7, 36.6, 41.8, 44.0, 86.2 (SꢀCꢀS).
IR (KBr): 1120 cm−1. MS: m/z 284 [M+]. Anal. Calc.
for C15H24OS2: C, 63.33; H, 8.50. Found: C, 63.63; H,
8.67%.
1
prisms, m.p. (dec) 110°C (EtOH). H-NMR: l 1.40 (br
4.4.4. (1R*,3R*)-3-(1-Adamantyl)-3-tert-butyldithiirane
1-oxide (trans-4a)
s, 9H), 1.63 (br s, 6H), 2.00 (br s, 3H), 2.14 (br s, 6H).
13C-NMR: l 29.3, 32.7, 36.5, 43.7, 45.5, 47.7, 115.4
(S–C–S). MS m/z 332 [M+]. Anal. Calc. for C14H24S4:
C, 54.17; H, 7.27. Found: C, 54.36; H, 7.33.
Colorless solid; m.p. (dec) 99–100°C (EtOH). 1H-
NMR (CDCl3): l 1.44 (s, 9H), 1.61 (pseudo ABq,
J=11 Hz, 6H), 1.74 (pseudo d, J=12 Hz, 3H), 1.84
(pseudo d, J=12 Hz, 3H), 1.97 (br s, 3H); (C6D6): l
1.38 (s, 9H), 1.35 (br s, 6H), 1.52 (br s, 6H), 1.65 (br s,
3H). 13C-NMR: l 28.7, 32.2 (br), 36.4, 39.5, 41.9, 43.5,
87.7 (SꢀCꢀS). IR (KBr) 1123 cm−1. MS: m/z 284 [M+].
Anal. Calc. for C15H24OS2: C, 63.33; H, 8.50. Found:
C, 63.72; H, 8.58%.
4.3. Preparation of 5,5-di(1-adamantyl)tetrathiolane (3b)
In a manner similar to that described above, 5,5-di(1-
adamantyl)tetrathiolane (3b) (66 mg, 28%) was pre-
pared by the reaction of the thioketone 7b (180 mg,
0.57 mmol) and S2Cl2 (154 mg, 1.14 mmol). Yellow
prisms: m.p. (dec) 136–137°C (EtOH). 1H-NMR: l
1.63 (br s, 12H), 1.00 (br s, 15H), 2.55 (br s, 3H).
13C-NMR: l 29.4, 36.5, 43.5, 48.5, 116.7 (S–C–S). MS
m/z 410 [M+]. Anal. Calc. for C21H30S4: C, 61.41; H,
7.36. Found: C, 61.61; H, 7.34.
4.5. Reaction of (1R*,3S*)-3-(1-adamantyl)-3-tert-
butyldithiirane 1-oxide (cis-4a) with Ph3P
A solution of cis-4a (7.0 mg, 0.025 mmol) and Ph3P
(7.2 mg, 0.028 mmol) in benzene (5 ml) was stirred for
1 h at room temperature. The solvent was removed
4.4. Oxidation of 5-(1-adamantyl)-5-tert-butyl-
tetrathiolane (3a)
1
under reduced pressure. The H-NMR spectrum of the
residue showed the exclusive formation of the (Z)-
sulfine 6a. The residue was subjected to column chro-
matography (CH2Cl2) to give Ph3PꢁS (6.9 mg, 85%)
and the (Z)-6a (4.9 mg, 79%).
4.4.1. Four molar equi6alents of DMD
To a solution of tetrathiolane 3a (95 mg, 0.29 mmol)
in dichloromethane (16 ml) cooled at −78°C was
added DMD (0.098 M, 12 ml, 1.18 mmol). The mixture
was stirred for 1 h at −78°C and then for 4 h at room
temperature. The solvent was removed under reduced
pressure and the residue was purified with GPC to give
a mixture of the dithiirane 1-oxides, cis- and trans-4a,
(51 mg, 62%). The mixture was further separated with
4.5.1. 1-Adamantyl tert-butyl thioketone (Z)-S-oxide
[(Z)-6a]
1
Colorless crystals; m.p. 89–90°C (EtOH). H-NMR
(CDCl3): l 1.37 (s, 9H), 1.71 (pseudo d, J=12 Hz, 3H),
1.82 (pseudo d, J=12 Hz, 3H), 2.03 (br s, 3H), 2.40

A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
133
1
(pseudo d, J=2.4 Hz, 6H). H-NMR (C6D6): l 0.99 (s,
C21H30OS: C, 76.31; H, 9.15. Found: C, 76.20; H,
9.26%.
9H), 1.59 (pseudo d, J=12 Hz, 3H), 1.75 (pseudo d,
J=11 Hz, 3H), 1.91 (br s, 3H), 2.39 (pseudo d, J=2.6
Hz, 6H). 13C-NMR: l 28.9, 31.0, 36.5, 38.8, 40.6, 47.4,
216.0; IR (KBr) 1053, 1102 cm−1. MS: m/z 252 [M+].
Anal. Calc. for C15H24OS: C, 71.38; H, 9.58. Found: C,
70.86; H, 9.61%.
4.8. Isolation of (2R*,3R*)-5-(1-adamantyl)-5-tert-
butyltetrathiolane 2,3-dioxide (5)
To a solution of tetrathiolane 3a (48.3 mg, 0.15
mmol) in dichloromethane (8 ml) cooled at −20°C was
added DMD (0.080 M, 7.5 ml, 0.60 mmol), and the
mixture was stirred for 1.3 h. The volatile materials
were removed in vacuo below −20°C and the residue
was recrystallized below −20°C from a mixed solvent
of dichloromethane and ethanol. The recrystallization
was repeated three times to give analytically pure 2,3-
dioxide 5 (15.3 mg, 28%) as pale-yellow, fine plates.
4.6. Reaction of (1R*,3R*)-3-(1-adamantyl)-3-tert-
butyldithiirane 1-oxide (trans-4a) with Ph3P
In a similar manner, trans-4a (9.1 mg, 0.032 mmol)
was treated with Ph3P (8.6 mg, 0.033 mmol) in benzene
(5 ml) to give Ph3PꢁS (8.3 mg, 86%) and the (E)-sulfine
[(E)-6a] (7.5 mg, 93%).
1
M.p. (dec) 65–66° (CH2Cl2–EtOH). H-NMR (263 K):
4.6.1. 1-Adamantyl tert-butyl thioketone (E)-S-oxide
[(E)-6a)]
Colorless crystals; m.p. 79–81°C (EtOH). H-NMR
(CDCl3): l 1.56 (s, 9H), 1.72 (pseudo ABq, J=12 Hz,
6H), 2.02 (br s, 6H), 2.07 (br s, 3H). H-NMR (C6D6):
l 1.39 (pseudo d, J=11 Hz, 3H), 1.49 (pseudo d,
J=13 Hz, 3H), 1.50 (s, 9H), 1.64 (pseudo d, J=2.6
Hz, 6H), 1.73 (br s, 3H). 13C-NMR: l 28.2, 29.8, 36.2,
39.5, 40.8, 44.1, 216.9. IR (KBr) 1056, 1125 cm−1. MS:
m/z 252 [M+]. Anal. Calc. for C15H24OS: C, 71.38; H,
9.58. Found: C, 71.28; H, 9.60%.
l 1.45 (br s, 9H), 1.65 (br s, 6H), 2.09 (br s, 9H).
13C-NMR (263 K): l 29.2 (CH), 33.4 (br s, CH3), 35.9
(CH2), 42.2 (CH2), 44.5 (C), 46.9 (C), 153.9 (C); IR
(KBr, 298 K) 1134, 1104 cm−1. Anal. Calc. for
C15H24O2S4: C, 49.42; H, 6.63. Found: C, 48.84; H,
6.57.
1
1
4.9. X-ray crystallography of 2,3-dioxide 5
Single crystals of 5 for X-ray crystallographic analy-
sis were obtained by recrystallization from a mixed
solvent of dichloromethane and hexane; the two poly-
morphic crystals, pale-yellow plates (major, m.p. (dec)
74–76°C) and yellow prisms (minor, m.p. (dec) 67–
4.7. Oxidation of 5,5-di(1-adamantyl)tetrathiolane (3b)
To a solution of 3b (41.5 mg, 0.10 mmol) in
dichloromethane (8 ml) cooled at −78°C was added
DMD in acetone (0.07 M, 1.7 ml, 0.12 mmol). After
stirring at −78°C for 5 h, the solvent was removed
under reduced pressure to give a green–yellow oily
residue. The residue was purified by HPLC to afford
sulfine 6b (4.1 mg, 12%), dithiirane 1-oxide 4b (14.0 mg,
38%), thioketone 7b (7.9 mg, 25%), and tetrathiolane 3b
(5.7 mg, 14%).
68°C), were mechanically separated under
microscope.
a
Yellow prisms: C15H24O2S4, Mw 364.59. Monoclinic,
space group P21/n, a=6.4150(3), b=18.878(1), c=
3
,
,
13.7410(9) A, i=97.349(4), V=1650.4(2) A , Z=4,
zcalc=1.467 g cm−3, v(Mo–Ka)=5.54 mm−1. A yel-
low prism with dimensions 0.30×0.12×0.10 mm was
mounted on a Mac Science DIP3000 diffractometer
with a graphite-monochromater. Oscillation and non-
screen Weissenberg photographs were recorded on the
imaging plates of the diffractometer by using Mo–Ka
4.7.1. 3,3-Di-(1-adamantyl)dithiirane 1-oxide (4b)
Colorless plates; m.p. (dec) 143–144°C (EtOH). H-
1
,
radiation (u=0.71073 A) at 153 K and the data reduc-
NMR: l 1.56–1.86 (m, 18H), 1.96 (br s, 3H), 2.04 (br
s, 3H), 2.21 (br s, 6H). 13C-NMR: l 28.7 (CH), 29.7
(CH), 36.4 (CH2), 36.6 (CH2), 39.5 (CH2), 44.1 (C),
44.7 (C), 87.4 (S–C–S) (one CH2 carbon was not
tion was made by the MAC DENZO program system.
Intensity data of 4111 independent reflections were
collected in the range of 05h57, 05k526, −195
l519. Cell parameters were determined and refined by
using the MAC DENZO for all observed reflections. The
structure was solved by direct methods using SIR [32] in
observed under the conditions); IR (KBr) 1118 cm−1
;
MS m/z 362 [M+]. Anal. Calc. for C21H30OS2: C, 69.56;
H, 8.34. Found: C, 69.74; H, 8.51.
the CRYSTAN-GM program system. The atomic coordi-
nates and anisotropic thermal parameters of the non-H
atoms were refined by full-matrix least squares to mini-
mize the functions, S(ꢀFoꢀ−ꢀFcꢀ)2, for 3683 reflections [I
4.7.2. Di-1-adamantyl thioketone S-oxide (6b)
Colorless crystals; m.p. 159–160°C (EtOH). 1H-
NMR: l 1.65–1.85 (m, 12H), 2.03 (br s, 12H), 2.44
(pseudo d, J=2.4 Hz, 6H). 13C-NMR: l 28.3, 29.0,
36.2, 36.6, 39.0, 41.0, 44.7, 47.9, 216.6; IR (KBr) 1018,
1086 cm−1; MS m/z 330 [M+]. Anal. Calc. for
2|(I)] (286 parameters). The final R (Rw)=0.077
–
(0.086) and GOF=3.761; max/min residual electron
−3
,
density=2.06/−1.97 e A
.

134
A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
4.12. Decomposition of tetrathiolane 2,3-dioxide 5 in
Pale-yellow plates: intensity data of 2565 independent
the presence of 2,3-dimethyl-1,3-butadiene and
norbornene
reflections were collected in the range of 05h59,
05k519, 05l525. Orthorhombic, space group
,
P2nn, a=6.5200(6), b=13.970(1), c=18.386(2) A,
3
V=1665.6(3) A , Z=4, zcalc. =1.454
g
cm−3
,
In a similar manner, decomposition of 2,3-dioxide 5
(4.7 mg, 0.013 mmol) in the presence of 2,3-dimethyl-
1,3-butadiene (8.5 mg, 0.103 mmol) and norbornene
(9.9 mg, 0.105 mmol) in CDCl3 (0.4 ml) at 294 K was
monitored by 1H-NMR. Triptycene was used as the
internal standard. The yields of the products were
,
v(Mo–Ka)=5.49 mm−1. Refinement was performed
for 1992 reflections [I52|(I)] (210 parameters). The
structure was solved as a mixture consisted of 86%
of one enantiomer (2R,3R or 2S,3S) and 14% of the
other. The final R (Rw)=0.090 (0.094) and GOF=
1
obtained from the integral ratios in the H-NMR spec-
3.422; max/min residual electron density=2.37/−0.83
tra measured before and after evaporation of the sol-
vent and unreacted trapping reagents: dithiin 1-oxide
15, 72; trithiolane 16, 3; cis-dithiirane 1-oxide 4a, 53;
trans-4a, 34; thioketone 7a, 10; tetrathiolane 3a, 3%.
−3
,
e A
.
4.10. Decomposition of tetrathiolane 2,3-dioxide 5 in
the presence of 2,3-dimethyl-1,3-butadiene
4.13. Preparation of 4,5-dimethyl-3H,6H-1,2-dithiin
1-oxide (15)
Decomposition of 2,3-dioxide 5 in the presence of
2,3-dimethyl-1,3-butadiene was carried out in CDCl3
1
and monitored by H-NMR, where yields of the prod-
To a solution of 4,5-dimethyl-3H,6H-1,2-dithiin [33]
(40 mg, 0.27 mmol) in dichloromethane (5 ml) was
added DMD (0.07 M, 4 ml, 0.28 mmol) at −78°C. The
mixture was stirred for 1.5 h at −78°C and allowed to
warm to 0°C. The solvent was removed under reduced
pressure at 0°C to give spectroscopically pure 4,5-
dimethyl-3H,6H-1,2-dithiin 1-oxide (15) as a pale-yel-
ucts were determined by comparing their integral ratios
with that of the internal standard dibenzyl.
To 2,3-dioxide 5 (5.5 mg, 0.015 mmol) placed in an
NMR sample tube was added a 0.021 M CDCl3 solu-
tion (0.4 ml) of dibenzyl containing 1,3-dimethyl-1,3-
butadiene (10.2 mg, 0.124 mmol) at room temperature.
Decomposition of 5 was monitored by 1H-NMR at
297.790.1 K. Final yields of products were obtained
from the integral ratio in the 1H-NMR spectrum after 4
h: the dithiin 1-oxide 15, 87; cis-dithiirane 1-oxide 4a,
53; trans-4a, 33; thioketone 7a, 11; tetrathiolane 3a,
3%. The yield of 15 was calculated based on the as-
sumption that 1 mol of 5 generates 1 mol of S2O which
provides 1 mol of 15. Signals for 15 was specified by
comparison with those of the authentic sample (see
section 4.13).
1
low oil. H-NMR: l 1.96 (s, 3H), 2.02 (s, 3H), 3.18 (d,
1H, J=13.9 Hz), 3.23 (d, 1H, J=13.6 Hz), 3.76 (d,
1H, 13.8 Hz), 3.92 (d, 1H, J=13.4 Hz). 13C-NMR: l
19.7, 21.9, 34.0, 60.2, 123.7, 131.2; IR (neat) 1074
cm−1. Anal. Calc. for C6H10OS2: C, 44.41; H, 6.21.
Found: C, 43.99; H, 6.09% (for a sample purified by
GPC).
5. Supplementary material
Complete lists of bond lengths and angles, hydrogen
atom coordinates and anisotropic thermal parameters
have been deposited at the Cambridge Crystallographic
Data Centre (No. CCDC-141119). Copies of this infor-
mation may be obtained free of charge from: The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (Fax: +44-1223-336-033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
4.11. Decomposition of tetrathiolane 2,3-dioxide 5 in
the presence of norbornene
In a similar manner, decomposition of 2,3-dioxide 5
(3.8 mg, 0.0105 mmol) in the presence of norbornene
(9.5 mg, 0.101 mmol) in CDCl3 (0.4 ml) at 297.590.6
1
K was monitored by H-NMR. In this case, triptycene
was employed as the internal standard. The signals due
to 2,3-dioxide 5 disappeared mostly after 90 min. The
solvent and unreacted norbornene was removed under
reduced pressure: trithiolane 16 [28], 85; cis-dithiirane
1-oxide 4a, 50; trans-4a, 38; thioketone 7a, 10; tetrathi-
olane 3a, 2%. The yield of 16 was calculated based on
the assumption that 1 mol of 5, after disproportiona-
tion of S2O, gives 0.5 mol of S3, which yields 0.5 mol of
16.
Acknowledgements
This work was supported by a Grant-in-Aid for
Scientific Research on Priority Areas (no. 10133206)
from the Ministry of Education, Science, Sports and
Culture of Japan.

A. Ishii et al. / Journal of Organometallic Chemistry 611 (2000) 127–135
135
References
[18] (a) N. Yomoji, S. Satoh, S. Ogawa, R. Sato, Tetrahedron Lett.
34 (1993) 673. (b) T. Kimura, M. Hanzawa, E. Horn, Y. Kawai,
S. Ogawa, R. Sato, Tetrahedron Lett. 38 (1997) 1607. (c) T.
Kimura, Y. Kawai, S. Ogawa, R. Sato, Chem. Lett. (1999) 1305.
[19] A. Ishii, S. Nakamura, J. Nakayama, Tetrahedron 53 (1997)
12203.
[20] (a) S.-Y. Tang, C.W. Brown, Inorg. Chem. 14 (1975) 2856. (b)
A.G. Hopkins, S.-Y. Tang, C.W. Brown, J. Am. Chem. Soc. 95
(1973) 3486.
[1] (a) A. Ishii, T. Akazawa, M.-X. Ding, T. Honjo, J. Nakayama,
M. Hoshino, M. Shiro, J. Am. Chem. Soc. 115 (1993) 4914. (b)
A. Ishii, T. Akazawa, T. Maruta, J. Nakayama, M. Hoshino, M.
Shiro, Angew. Chem. Int. Ed. Engl. 33 (1994) 777. (c) A. Ishii,
T. Maruta, K. Teramoto, J. Nakayama, Sulfur Lett. 18 (1995)
237. (d) A. Ishii, Y.-N. Jin, H. Nagaya, M. Hoshino, J.
Nakayama, Tetrahedron Lett. 36 (1995) 1867. (e) A. Ishii, T.
Akazawa, M.-X. Ding, T. Honjo, T. Maruta, S. Nakamura, H.
Nagaya, M. Ogura, K. Teramoto, M. Shiro, M. Hoshino, J.
Nakayama, Bull. Chem. Soc. Jpn. 70 (1997) 509. (f) A. Ishii,
Yuki Gosei Kagaku Kyokaishi, 55 (1997) 897. (g) A. Ishii, K.
Umezawa, J. Nakayama, Tetrahedron Lett. 38 (1997) 1431.
[2] (a) A. Ishii, Y.-N. Jin, Y. Sugihara, J. Nakayama, J. Chem. Soc.
Chem. Commun. (1996) 2681. (b) Y.-N. Jin, A. Ishii, Y. Sugi-
hara, J. Nakayama, Heterocycles 44 (1997) 255.
[21] For reviews on S2O, see: (a) A.R.V. Murthy, T.R.N. Kutty,
D.K. Sharma, Int. J. Sulfur Chem. 6 (1971) 161. (b) E. Fluck,
Chem.-Ztg., 104 (1980) 252.
[22] (a) G.A. Urove, M.E. Welker, Organometallics 7 (1988) 1013.
(b) M.E. Raseta, S.A. Cawood, M.E. Welker, A.L. Rheingold, J.
Am. Chem. Soc. 111 (1989) 8268. (c) D.S. Brown, C.F. Owens,
B.G. Wilson, M.E. Welker, A.L. Rheingold, Organometallics 10
(1991) 871 and references cited therein. (d) For reviews, see:
W.A. Schenk, Angew. Chem. Int. Ed. Engl. 26 (1987) 98. (e)
K.K. Pandey, Prog. Inorg. Chem. 40 (1992) 445. (f) A.F. Hill,
Adv. Organomet. Chem. 36 (1994) 159.
[23] (a) S2O: U. Blukis, R.J. Myers, J. Phys. Chem. 69 (1965) 1154.
(b) L.F. Phillips, J.J. Smith, B. Meyer, J. Mol. Spectrosc. 29
(1969) 230. (c) B. Hapke, F. Graham, Icarus 79 (1989) 47. (d) Q.
Zhang, P. Dupre´, B. Grzybowski, P.H. Vaccaro, J. Chem. Phys.
103 (1995) 67. (e) S3: B. Meyer, T. Stroyer-Hansen, T.V. Oom-
men, J. Mol. Spectrosc. 42 (1972) 335. (f) P. Lenain, E. Picque-
nard, J.L. Lesne, J. Corset, J. Mol. Struct. 142 (1986) 355.
[24] (a) S2O: R.D. Davy, E. Skoumbourdis, Mol. Phys. 94 (1998)
539. (b) T. Mu¨ller, P. Dupre´, P.H. Vaccaro, F. Pe´rez-Bernal, M.
Ibrahim, F. Iachello, Chem. Phys. Lett. 292 (1998) 243. (c) S3:
D.R. Salahub, A.E. Foti, V.H. Smith Jr., J. Am. Chem. Soc. 100
(1978) 7847. (d) M. Toscano, N. Russo, J. Rubio, J. Chem. Soc.
Faraday Trans. 92 (1996) 2681. (e) K.K. Baeck, J.D. Watts, R.J.
Bartlett, J. Chem. Phys. 107 (1997) 3853. (f) S2O, S3: C.H.
Patterson, R.P. Messmer, J. Am. Chem. Soc. 112 (1990) 4138.
(g) J. Ivanic, G.J. Atchity, K. Ruedenberg, J. Chem. Phys. 107
(1997) 4307.
[3] Y.-N. Jin, A. Ishii, Y. Sugihara, J. Nakayama, Tetrahedron Lett.
39 (1998) 3525.
[4] A. Ishii, M. Nakabayashi, J. Nakayama, J. Am. Chem. Soc. 121
(1999) 7959.
[5] For reviews, see: (a) F. Freeman, Chem. Rev. 84 (1984) 117. (b)
E. Clennan, K.L. Stensaas, Org. Prep. Proced. Int. 30 (1998) 551.
(c) S. Oae, Kagaku 33 (1978) 240. (d) S. Oae, T. Takata, Kagaku
34 (1979) 891.
[6] For recent papers on 6ic-disulfoxides: (a) F. Freeman, C. Lee, J.
Org. Chem. 53 (1988) 1263. (b) E. Block, T. Bayer, J. Am.
Chem. Soc. 112 (1990) 4584. (c) D. Gu, D.N. Harpp, Tetrahe-
dron Lett. 34 (1993) 67. (d) E.L. Clennan, H. Zhang, J. Org.
Chem. 59 (1994) 7952. (e) J. Nakayama, A. Mizumura, Y.
Yokomori, A. Krebs, K. Schu¨tz, Tetrahedron Lett. 36 (1995)
8583. (f) E.L. Clennan, K.L. Stensaas, J. Org. Chem. 61 (1996)
7911 and references cited therein.
[7] (a) F. Freeman, C.N. Angeletakis, J. Am. Chem. Soc. 103 (1981)
6232. (b) F. Freeman, C.N. Angeletakis, J. Am. Chem. Soc. 104
(1982) 5766. (c) F. Freeman, C.N. Angeletakis, J. Am. Chem.
Soc. 105 (1983) 4039. (d) P.L. Folkins, D.N. Harpp, J. Am.
Chem Soc. 113 (1991) 8998.
[8] (a) W. Adam, J. Bialas, L. Hadjiarapoglou, Chem. Ber. 124
(1991) 2377. (b) W. Adam, L. Hadjiarapoglou, A. Smerz, Chem.
Ber. 124 (1991) 227.
[25] For examples, see: (a) C.Y. Na, L.W. Esposito, Icarus 125 (1997)
364. (b) J.R. Spencer, A.S. McEwen, M.A. McGrath, P. Sar-
toretti, D.B. Nash, K.S. Noll, D. Gilmore, Icarus 127 (1997) 221.
[26] R.M. Dodson, V. Srinivasan, K.S. Sharma, R.F. Sauers, J. Org.
Chem. 37 (1972) 2367.
[9] K.W. Buck, A.B. Foster, W.D. Pardoe, M.H. Qadir, J.M. Web-
ber, J. Chem. Soc. Chem. Commun. (1966) 759.
[27] T. Ghosh, P.D. Bartlett, J. Am. Chem. Soc. 110 (1988) 7499.
[28] P.D. Bartlett, T. Ghosh, J. Org. Chem. 52 (1987) 4937.
[29] (a) T.C. Shields, A.N. Kurtz, J. Am. Chem. Soc. 91 (1969) 5415.
(b) K. Steliou, P. Salama, D. Brodeur, Y. Gareau, J. Am. Chem.
Soc. 109 (1987) 926. (c) K. Steliou, Y. Gareau, G. Milot, P.
Salama, Phosphorus Sulfur Silica 43 (1989) 209. (d) R. Sato, S.
Satoh, M. Saito, Chem. Lett. (1990) 139. (e) K. Steliou, Y.
Gareau, G. Milot, P. Salama, J. Am. Chem. Soc. 112 (1990)
7819. (f) T.L. Gilchrist, J.E. Wood, J. Chem. Soc. Chem. Com-
mun. (1992) 1460. (g) A.S. Micallef, S.E. Bottle, Tetrahedron
Lett. 38 (1997) 2303. (h) R.F. English, O.A. Rakitin, C.W. Rees,
O.G. Vlasova, J. Chem. Soc. Perkin Trans. 1 (1997) 201.
[30] For reviews on chemical reactivities of S2, see: (a) D.N. Harpp,
Phosphorus Sulfur Silicon 120–121 (1997) 41. (b) S.L. Tardif,
A.Z. Rys, C.B. Abrams, I.A. Abu-Yousef, P.B.F. Leste´-Lasserre,
E.K.V. Schultz, D.N. Harpp, Tetrahedron 53 (1997) 12225. (c)
K. Steliou, Acc. Chem. Res. 24 (1991) 341.
[10] (a) T. Bayer, H. Wagner, E. Block, S. Grisoni, S.H. Zhao, A.
Neszmelyi, J. Am. Chem. Soc. 111 (1989) 3085. (b) E. Juaristi,
J.S. Cruz-Sanchez, A. Petsom, R.S. Glass, Tetrahedron 44 (1988)
5653. (c) J.J. Rigau, C.C. Bacon, C.R. Johnson, J. Org. Chem.
35 (1970) 3655.
[11] A. Ishii, M. Saitoh, J. Nakayama, unpublished results.
[12] For retention of configuration in desulfurization of episulfides by
Ph3P, see: (a) N.P. Neureiter, F.G. Bordwell, J. Am. Chem. Soc.
81 (1959) 578. (b) A.I. Meyers, M.E. Ford, J. Org. Chem. 41
(1976) 1735.
[13] The structure of the precursor for 4a was previously [3] assumed
to be the tetrathiolane 1-oxide and now should read the 6ic-
disulfoxide (5).
[14] S. Lacombe, M. Loudet, A. Dargelos, E. Robert-Banchereau, J.
Org. Chem. 63 (1998) 2281.
[15] D.N. Harpp, J.G. Gleason, J. Org. Chem. 36 (1971) 1314.
[16] E. Juaristi, M. Ordon˜ez, in: P. Page (Ed.), Organosulfur Chem-
istry, vol. 2, Academic Press, San Diego, CA, 1998 (Chapter 3).
[17] F. Wudl, R. Gruber, A. Padwa, Tetrahedron Lett. (1969)
2133.
[31] R. Okazaki, K. Inoue, N. Inamoto, Bull. Chem. Soc. Jpn. 54
(1981) 3541.
[32] A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliard, M.C.
Burla, G. Polidori, M. Camalli, J. Appl. Cryst. 27 (1994) 435.
[33] A.Z. Rys, D.N. Harpp, Tetrahedron Lett. 38 (1997) 4931.
.