Stereoselective synthesis of substituted bicyclo[3.1.1]heptanes: II.*Synthesis of all diastereoisomers of 7-methyl-and 7-phenylbicyclo[3.1. 1]hept-6-yl phenyl sulfones from tricyclo[4.1.0.02,7]heptane precursors

Article abstract of DOI:10.1134/s1070428008030020

All four possible diastereoisomers of 7-methyl-and 7-phenylbicyclo[3.1.1] hept-6-yl phenyl sulfones were intentionally synthesized from tricyclo[4.1.0.0^2,7]heptane and 1-phenyltricyclo[4.1.0.0 ^2,7]heptane, respectively. The key stage

Full text of DOI:10.1134/s1070428008030020

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 3, pp. 325–330. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © V.A. Vasin, S.G. Kostryukov, S.Yu. Vovod, P.S. Petrov, F.A. Kryuchkov, V.V. Razin, 2008, published in Zhurnal Organicheskoi
Khimii, 2008, Vol. 44, No. 3, pp. 333–338.
Stereoselective Synthesis of Substituted Bicyclo[3.1.1]heptanes:
II.* Synthesis of All Diastereoisomers of 7-Methyl-
and 7-Phenylbicyclo[3.1.1]hept-6-yl Phenyl Sulfones
from Tricyclo[4.1.0.02,7]heptane Precursors
V. A. Vasina, S. G. Kostryukova, S. Yu. Vovoda, P. S. Petrova,
F. A. Kryuchkovb, and V. V. Razinb
a Ogarev Mordovian State University, ul. Bol’shevistskaya 68, Saransk, 430000 Rissia
e-mail: vasin@mrsu.ru
b St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia
Received July 11, 2007
Abstract—All four possible diastereoisomers of 7-methyl- and 7-phenylbicyclo[3.1.1]hept-6-yl phenyl
sulfones were intentionally synthesized from tricyclo[4.1.0.02,7]heptane and 1-phenyltricyclo[4.1.0.02,7]heptane,
respectively. The key stage in the synthesis was regio- and stereoselective cleavage of the central bicyclobutane
C1–C7 bond in the tricycloheptane precursors by the action of radical, nucleophilic, and electrophilic reagents.
The NMR spectra of the diastereoisomers were compared.
DOI: 10.1134/S1070428008030020
Tricyclo[4.1.0.02,7]heptane (I) is one of the most
accessible bicyclo[1.1.0]butane derivatives. Compound
I and its 1-phenyl-substituted derivative II are ob-
tained according to Moore via dibromocyclopropana-
tion–debromination of cyclohexene and 1-phenylcy-
clohexene, respectively [2, 3]. Due to relatively high
CH acidity, hydrocarbons I and II can be converted
into other tricycloheptane derivatives by preliminary
metalation at the bridgehead position, followed by re-
action with electrophiles. For example, the transforma-
tions of I into III [4] and of II into IV have been
reported [5].
group [9]) is present at the bridgehead position, while
the presence of a donor group, e.g., phenyl ring [10],
activates the above bond toward electrophiles. Finally,
additions to tricycloheptane derivatives are charac-
terized by strict endo-selectivity of the primary attack
by any reagent (radical, electrophilic, or nucleophilic)
on the C1–C7 bond [6–10].
The above listed specific features of the chemical
behavior of tricycloheptane derivatives allowed us to
hope that 6- and 7-substituted norpinanes having
a required configuration could be synthesized. It
should be emphasized that purposeful synthesis of
such compounds is a fairly difficult problem. In the
present communication we describe the synthesis of all
four possible diastereoisomers of two 6,7-disubstituted
norpinane derivatives, phenyl sulfones V and VI, as
a possible solution of this problem. Scheme 1 illus-
trates the syntheses of diastereoisomeric sulfones Va–
Vd. Here, the tricycloheptane precursor was 1-methyl-
tricyclo[4.1.0.02,7]heptane (III) which is available from
tricycloheptane I via organolithium replacement [4].
Specificity of the electronic structure predetermines
the mode of cleavage of the tricycloheptane system by
the action of radical [6] and in some cases nucleophilic
and electrophilic reagents: rupture of the central bi-
cyclobutane C1–C7 bond leads to the formation of bi-
cyclo[3.1.1]heptane derivatives [7]. For example, addi-
tion of benzenethiol to compound I and subsequent
hydrodesulfurization gives unsubstituted norpinane
(bicyclo[3.1.1]heptane) [8], and this reaction underlies
the most efficient procedure for its preparation.
Cleavage of the C1–C7 bond by the action of a nu-
cleophilic reagent is possible only when a strong elec-
tron-withdrawing substituent (such as phenylsulfonyl
In keeping with Scheme 1, tricycloheptane III was
brought into known [8] reaction with benzenethiol,
which afforded a mixture of two stereoisomeric nor-
pinane sulfides. Their oxidation with NaIO4–KMnO4
325

VASIN et al.
326
Scheme 1.
t-BuOK
Me
SO2Ph
Me
(1) PhSH
(2) [O]
SO2Ph
Va
Vb
Vc
t-BuOK
SO2Ph
Me
Me
SO2Ph
Vd
Me
III
H2, Pd/C
PhSO2Br
t-BuOK
Me
SO2Ph
H2C
SO2Ph
Br
VII
VIII
in acetone at 20°C in the presence of MgSO4 [11]
gave the corresponding diastereoisomeric sulfones Va
(endo,syn isomer) and Vb (endo,anti isomer). Each
sulfone Va and Vb was isolated by column chromatog-
raphy on aluminum oxide. The configuration of com-
pounds Va and Vb is predetermined at the stage of
addition of benzenethiol to tricycloheptane III: phenyl-
sulfanyl radical attacks the C1–C7 bond with strict endo-
selectivity and exclusively at the unsubstituted C1
atom, while the subsequent hydrogen transfer is not
stereoselective. Epimerization of sulfone Va by the
action of potassium tert-butoxide in THF gave the
third exo,syn isomer Vc. Finally, the forth exo,anti
isomer Vd was synthesized by a sequence of three re-
actions. In the first step, radical addition of benzene-
sulfonyl bromide to hydrocarbon III resulted in stereo-
Scheme 2.
PhSO2Br
Ph3SnH
t-BuOK
Ph
SO2Ph
Ph
SO2Ph
Ph
Br
SO2Ph
IX
VIa
VIc
LiAlH4
Ph
II
SO2Ph
(1) BuLi
(2) PhSO2F
Ph
VIb
NaBH4
CF3COOH
Ph
SO2Ph
t-BuOK
VIb
IV
Ph
SO2Ph
VId
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STEREOSELECTIVE SYNTHESIS OF SUBSTITUTED BICYCLO[3.1.1]HEPTANES: II.
327
Table 1. 1H NMR spectra of compounds Va–Vd and VIa–VId, δ, ppm (J, Hz)
Comp.
no.
exo-2-H, endo-2-H,
exo-4-H endo-4-H
1-H, 5-H
exo-3-H endo-3-H
7-H
6-H
Me
Ph
7.52–7.67 m (3H),
Va
2.60 br.s 2.32–2.46 1.79–1.91 2.11–2.27 1.62–1.77 2.06 sext
3.33 t
1.02 d
(J = 6.5) (J = 5.4) (J = 7.3) 7.92 d (2H, J = 7.3)
3.62 t 1.10 d 7.48–7.68 m (3H),
(J = 5.8) (J = 7.3) 7.87 d (2H, J = 7.3)
3.26 s 0.90 d 7.49–7.69 m (3H),
(J = 6.5) 7.91 d (2H, J = 7.3)
1.50 d 7.50–7.69 m (3H),
(J = 2.9) (J = 7.3) 7.90 d (2H, J = 7.3)
Vb 2.57 br.s
2.35 br.s 1.71–2.15
Vc
2.77 d
1.91–2.07 1.74–1.85 1.53–1.70
3.27 m
(J = 4.3)
Vd 2.62 br.s 2.01–2.14 1.85–1.98 1.72–1.84
1.59–1.71 3.10 d
VIa 3.21–3.30a 2.57–2.70 1.90–2.05 1.55–1.70 0.81–0.98 a3.21–3.30a 3.41 t
–
7.12 d (2H, J = 7.7),
7.20–7.40 m (3H),
7.57–7.72 m (3H),
7.96 d (2H, J = 7.0)
(J = 5.4)
VIb 3.00 br.d 2.73–2.87 2.09–2.24 2.06–2.20 1.90–2.06
VIc 3.35 br.d 2.15–2.27 1.70–1.85 1.25–1.39 0.90–1.08
VId 3.30 br.s 2.24–2.39 2.10–2.23 1.91–2.07 1.76–1.91
3.22 s
3.58 t
(J = 5.9)
–
–
–
7.21–7.38 m (5H),
7.50–7.68 m (3H),
7.85 d (2H, J = 7.3)
4.47 t
(J = 6.1)
3.05 s
7.05–7.39 m (5H),
7.55–7.75 m (3H),
8.00 d (2H, J = 7.3)
3.06 d
(J = 3.1) (J = 3.1)
3.23 d
7.22–7.43 m (5H),
7.43–7.65 m (3H),
7.70 d (2H, J = 7.3)
a
Signals from the 1-H, 5-H, and 6-H protons overlap each other, giving rise to unresolved multiplet.
selective formation of bromide VII. Compound VII
was subjected to dehydrobromination to obtain meth-
ylidenenorpinane VIII. Both these reactions were
described by us previously [12]. It should be noted that
the dehydrobromination process is accompanied by
change of the orientation of the phenylsulfonyl group.
In the final step, highly stereoselective catalytic hydro-
genation of compound VIII over Pd/C gave isomer
Vd. Here, the stereoselectivity is ensured by steric
hindrances created by the PhSO2 group to hydrogen
approach from the anti side. Epimerization of sulfone
Vd by the action of potassium tert-butoxide led to
already available isomer Vb.
synthesis of sulfone VIa was based on the oxidation of
known [8] adduct of II with benzenethiol in a way
similar to the preparation of sulfone Va. These trans-
formations were described in [5]. Epimerization of
sulfone VIa gave exo,syn isomer VIc (cf. the above
transformation of Va into Vc; Scheme 1). The two
other diastereoisomers of sulfone VI were synthesized
by hydrogenolysis of tricycloheptane IV in two dif-
ferent ways [13]. exo,anti Isomer VId was obtained by
ionic hydrogenation of IV using the system NaBH4–
CF3CO2H [14]. This transformation is an example of
addition of electrophilic hydrogen atom, where NaBH4
acts as hydride ion carrier. The stereoselectivity of this
process is the same as in the addition of methanol to
sulfone IV, catalyzed by a mineral acid [15]. Treat-
ment of sulfone VId with potassium tert-butoxide in
THF resulted in its complete epimerization into
endo,anti isomer VIb by analogy with the transforma-
tion of Vd into Vb. The same isomer (VIb) was also
synthesized by an alternative method, hydrogenation
of sulfone IV with lithium tetrahydridoaluminate
[9, 16]. These reactions may be regarded as examples
of nucleophilic addition to the activated bicyclobutane
Diastereoisomeric sulfones VIa–VId were synthe-
sized as shown in Scheme 2. Here, compound II and
sulfone IV were used as tricycloheptane precursors.
endo,syn Isomer VIa was obtained in two steps start-
ing from hydrocarbon II. In the first step, addition of
benzenesulfonyl bromide to II gave phenyl-substituted
analog of bromide VII, compound IX, which was
reduced with triphenylstannane in the second step. The
reduction occurred with retention of configuration at
the reaction center. An alternative procedure for the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 3 2008

VASIN et al.
Table 2. 13C NMR spectra of compounds Va–Vd and VIa–VId, δC, ppm
328
Compound no. C1, C5
C3
C2, C4
C6
C7
Me
Ph
Va
41.5
43.5
39.3
41.1
41.1
13.3
15.8
11.1
15.9
13.3
19.4
24.4
23.5
33.0
19.7
62.0
60.6
66.2
70.5
60.7
33.6
35.5
32.9
38.6
40.8
09.4
14.1
13.4
14.1
–
127.1, 129.0, 133.0, 140.8
127.3, 129.1, 133.1, 140.6
127.8, 129.1, 133.2, 139.6
127.2, 129.1, 133.0, 141.6
Vb
Vc
Vd
VIa
125.6, 125.7, 127.3, 128.1, 129.1, 133.1,
138.6, 140.5
VIb
VIc
VId
43.1
39.3
40.1
14.6
13.8
14.8
24.6
26.5
33.0
60.0
69.7
70.3
44.8
40.0
47.6
–
–
–
126.4, 127.0, 127.4, 128.6, 129.2, 133.2,
140.2, 140.3
125.4, 125.5, 128.0, 128.3, 129.3, 133.5,
139.4, 141.1
125.7, 126.9, 127.7, 127.9, 128.9, 133.0,
140.5
system. The reaction is initiated by attack by hydride
ion, and it leads to the formation of more stable addi-
tion product, isomer VIb, rather than VId.
at δ ~1.0 ppm, indicating syn orientation of the phenyl
group on C7; the signal is displaced upfield due to
shielding by the benzene ring. However, the 6-H signal
in the spectrum of VIc is a singlet, which means that
the PhSO2 group occupies exo position. The syn orien-
tation of the phenyl group on C7 in VIc is additionally
confirmed by the multiplicity and downfield position
of the 7-H signal (δ 4.47 ppm, t, J = 6.1 Hz); in this
case, the phenylsulfonyl group located opposite exerts
a deshielding effect. Thus the configuration of dia-
stereoisomers VIa and VIc may be regarded as con-
vincingly proved. The anti orientation of the phenyl
substituent on C7 in isomers VIb and VId was deter-
mined taking into account the absence of resonance
signals at about δ 1 ppm. In keeping with the data of
[17], the presence of a singlet from the 7-H proton and
a triplet from the 6-H proton (J = 5.8 Hz) in the spec-
trum of VIb allowed us to assign its configuration. In
the spectrum of VId, the 6-H and 7-H signals appear
as doublets with a coupling constant of 3.1 Hz. These
data unambiguously indicate endo,syn orientation of
6-H and 7-H: an appreciable long-range coupling be-
tween protons separated by four σ-bonds in norpinanes
(W-coupling [18]) can be observed only for that con-
figuration. Thus the configuration of diastereoisomer
VId was also determined.
We believe that application of the epimerization
method for the preparation of diastereoisomeric nor-
pinane sulfones deserves special comments. Interest-
ingly, epimerization at C6 in isomers Va (VIa) and Vd
(VId) occurs in different directions. This is explained
by different orientations of the methyl (phenyl) sub-
stituents in their molecules. The methyl (phenyl) and
phenylsulfonyl groups in molecules Vd and VId ap-
pear spatially close to each other, which is a destabi-
lizing factor; therefore, their epimerization involves
transition of the sulfonyl group to the endo position,
i.e., to give isomers Vb and VIb. By contrast, epimer-
ization of isomers Va and VIa, in which the methyl
(phenyl) group is oriented syn, leads to isomers Vc and
VIc with the phenylsulfonyl group located in the exo
position, as was observed for 6-endo-norpinyl phenyl
sulfone which was completely converted into 6-exo-
norpinyl phenyl sulfone [9].
Now let us consider the 1H and 13C NMR spectra of
diastereoisomers Va–Vd and VIa–VId (Tables 1, 2), in
particular their structure-related specificity which was
used to assign configuration of the isomers. Analysis
1
of the H NMR spectra of isomers VIa–VId is quite
sufficient to determine their configuration. The 6-H
signal in the spectra of VIa and VIb appear as a triplet
with a coupling constant of about 5.5 Hz, which un-
ambiguously indicates exo orientation of that proton;
otherwise, the vicinal coupling constants with 1-H
and 5-H would be much smaller [17]. Therefore, the
phenylsulfonyl group in VIa and VIb is oriented endo.
The exo-3-H proton in isomers VIa and VIc resonates
Comparison of the 13C NMR spectra of diastereo-
isomers VIa–VId showed the following configuration-
related differences. First, in the spectra of isomers VIc
and VId with exo orientation of the PhSO2 group, the
chemical shift of C6 is larger by ~10 ppm than that
found for compounds VIa and VIb with endo orienta-
tion of the same group. Second, analogous difference
is observed in the chemical shifts of C7: anti orienta-
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STEREOSELECTIVE SYNTHESIS OF SUBSTITUTED BICYCLO[3.1.1]HEPTANES: II.
329
tion of the phenyl group (VIb, VId) is characterized
by more downfield position of the C7 signal (by ~4–
7 ppm) as compared to isomers VIa and VIc with syn-
oriented phenyl group. Third, orientation of substit-
uents on C6 and C7 affects the chemical shifts of C2
and C4: endo,syn isomer VIa displays the C2 and C4
signals in a stronger field (by ~13 ppm) than does
exo,anti isomer VId.
precipitate of MnO2 was filtered off and washed with
chloroform (4×15 ml). The organic layer was separat-
ed and dried over MgSO4, and the solvent was re-
moved on a rotary evaporator. According to the
1H NMR data, the residue contained compounds Va
and Vb at a ratio of 77:23. Overall yield 87%. Indivi-
dual isomers Va and Vb were isolated by column chro-
matography on aluminum oxide and were additionally
purified by recrystallization.
b. A solution of 10 mmol of a mixture of the syn-
and anti-tricycloheptane III–benzenethiol adducts in
a mixture of 15 ml of acetic acid 20 ml of acetic
anhydride was cooled to 0°C, 20 ml of 30% hydrogen
peroxide was added, and the mixture was stirred for
1 h at 0°C and was then kept for 40 h at room tem-
perature. The acetic acid was evaporated under re-
duced pressure, the residue was neutralized with a so-
lution of Na2CO3, and the product was extracted into
diethyl ether (3×20 ml). The subsequent procedure
was the same as above in a. The ratio and overall yield
of compounds Va and Vb were similar to those in-
dicated above.
Configuration assignment of diastereoisomers Va–
1
Vd required comparison of both H and 13C NMR
spectra with account taken of the above relations. The
endo orientation of the PhSO2 group in isomers Va and
Vb follows both from the presence of a triplet signal
from 6-H and from the similar chemical shifts of C6.
The lowest chemical shift of C2/C4 in the 13C NMR
spectrum of isomer Va eventually confirms its con-
figuration and predetermines the configuration of Vb.
The structure of isomer Vd is supported by the pres-
ence of a doublet signal from 6-H (W-coupling), max-
imal (in the examined series) chemical shift of C2/C4,
and largest chemical shift of the methyl protons due to
deshielding effect of the oppositely located phenylsul-
fonyl group. Then the remaining diastereoisomer has
structure Vc.
syn-7-Methylbicyclo[3.1.1]hept-endo-6-yl phenyl
sulfone (Va). mp 93–94°C (from chloroform–hexane,
1:1), Rf 0.52. Found, %: C 66.94; H 7.11. C14H18O2S.
Calculated, %: C 67.17; H 7.25.
EXPERIMENTAL
anti-7-Methylbicyclo[3.1.1]hept-endo-6-yl phenyl
sulfone (Vb). mp 71–73°C, Rf 0.44. Found, %: C 67.14;
H 7.41. C14N18O2S. Calculated, %: C 67.17; H 7.25.
The elemental compositions were determined on
1
an HP-185B CHN analyzer. The H and 13C NMR
spectra were measured from solutions in CDCl3 on
a Bruker DPX-300 spectrometer (300.130 and
75.468 MHz, respectively). Analytical thin-layer chro-
matography was performed on Silufol UV-254 plates
using diethyl ether–hexane (1:1) as eluent; spots were
detected by treatment with iodine vapor. Preparative
separation of products and their purification were per-
formed by column chromatography on silica gel L
(40–100 μm) using light petroleum ether–ethyl acetate
(3:1) as eluent. Tricycloheptanes I [2], II [3], III [4],
and IV [5], and 7-methylidene-6-bicyclo[3.1.1]heptyl
phenyl sulfone (VIII) [12] were synthesized by known
methods.
anti-7-Methylbicyclo[3.1.1]hept-exo-6-yl phenyl
sulfone (Vd). An apparatus for catalytic hydrogenation
was charged with a solution of 0.5 g of compound
VIII in 10 ml of methanol, 15 mg of 5% Pd/C was
added, and hydrogenation was carried out at 20°C, fol-
lowing the absorption of hydrogen. The reaction was
complete in 20 min (a theoretical amount of hydrogen
was absorbed). The mixture was filtered, the filtrate
was evaporated, and the residue was purified by re-
crystallization from hexane–diethyl ether. Yield 0.41 g
(82%), mp 80–81°C, Rf 0.44. Found, %: C 67.22;
H 7.31. C14H18O2S. Calculated, %: C 67.17; H 7.25.
Phenyl syn-7-phenylbicyclo[3.1.1]hept-endo-6-yl
sulfone (VIa) was synthesized according to the pro-
cedure described in [5]. mp 142–143°C, Rf 0.50.
Base-catalyzed epimerization of sulfones Va, Vd,
VIa, and VId (general procedure). A glass ampule
was charged with a solution of 0.5 mmol of sulfone
Va, Vd, VIa, or VId in 5 ml of anhydrous THF, 50 mg
of powdered tert-butoxide was added, and the ampule
was sealed and heated for 6 h at 80°C. The ampule was
cooled and opened, the mixture was diluted with 20 ml
Sulfones Va and Vb. a. A solution of 2.14 g
(10 mmol) of NaIO4 and 9.48 g (60 mmol) of KMnO4
in 75 ml of distilled water was added over a period of
3 h to a solution of 10 mmol of a mixture of the syn-
and anti-tricycloheptane III–benzenethiol adducts (ob-
tained as described in [8]; isomer ratio 1:4, according
1
to the H NMR data) in 50 ml of acetone containing
6 g (50 mmol) of powdered anhydrous MgSO4 under
stirring at 20°C. The mixture was stirred for 10 h,
excess KMnO4 was reduced with Na2SO3, and the
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 3 2008

VASIN et al.
330
of water, neutralized with 10% hydrochloric acid, and
extracted with diethyl ether (3×20 ml).
mp 127–129°C. The product was identical to a sample
obtained by epimerization of sulfone VId (see above).
syn-7-Methylbicyclo[3.1.1]hept-exo-6-yl phenyl
sulfone (Vc) was obtained by epimerization of sulfone
Va. Yield 81%, mp 97–98°C (from diethyl ether–
hexane, 1:1), Rf 0.55. Found, %: C 66.90; H 7.17.
C14H18O2S. Calculated, %: C 67.17; H 7.25.
Sulfone Vb was obtained by epimerization of sul-
fone Vd. Yield 85%; the product contained about 10%
of initial sulfone Vd. Compound Vb was identified by
comparing its 1H NMR spectrum with that of a sample
prepared as described above.
Phenyl syn-7-phenylbicyclo[3.1.1]hept-exo-6-yl
sulfone (VIc) was obtained by epimerization of sul-
fone VIa. Yield 82%, mp 155–156°C (from chloro-
form–hexane), Rf 0.49. Found, %: C 72.89; H 6.34.
C19H20O2S. Calculated, %: C 73.04; H 6.45.
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9. Vasin, V.A., Kostryukov, S.G., Bolusheva, I.Yu., and
Razin, V.V., Zh. Org. Khim., 1993, vol. 29, p. 1349.
10. Christl, M., Advances in Strain in Organic Chemistry,
Greenwich: JAI, 1995, vol. 4, p. 163; Razin, V.A., Sovr.
Probl. Org. Khim., 1996, no. 11, p. 54.
11. Purrington, S.T. and Glenn, A.G., Org. Prep. Proced.
Int., 1985, vol. 17, p. 227.
12. Vasin, V.A., Kostryukov, S.G., Razin, V.V., Bolushe-
va, I.Yu., and Zefirov, N.S., Zh. Org. Khim., 1994,
vol. 30, p. 1351.
Phenyl anti-7-phenylbicyclo[3.1.1]hept-exo-6-yl
sulfone (VId). A mixture of 0.59 g (1.9 mmol) of
finely powdered sulfone IV and 0.72 g (19 mmol) of
powdered NaBH4 was carefully added in very small
portions over a period of 20 min to 15 ml of trifluoro-
acetic acid on cooling with an ice bath and vigorous
stirring in a strong stream of argon. The mixture was
stirred for an additional 5 min, trifluoroacetic acid was
removed under reduced pressure, and the residue was
treated with 5 ml of ice water and 5 ml of a saturated
solution of sodium chloride. The precipitate was fil-
tered off, dried in air, and purified by chromatography
using a short column charged with aluminum oxide.
Yield 0.244 g (41%), mp 134–135°C, Rf 0.43. Found,
%: C 72.87; H 6.37. C19H20O2S. Calculated, %:
C 73.04; H 6.45.
13. Vasin, V.A., Kostryukov, S.G., Vovod, S.Yu., Pet-
rov, P.S., and Razin, V.V., Russ. J. Org. Chem., 2007,
vol. 43, p. 1411.
Synthesis of sulfone VIb by reduction of tricyclo-
heptane IV with LiAlH4. A solution of 0.93 g
(3 mmol) of tricycloheptane IV in 10 ml of anhydrous
THF was cooled to 0°C, and 0.57 g (15 mmol) of
LiAlH4 was added under stirring in an argon atmos-
phere. The mixture was stirred for 3 h at room tem-
perature, 10 ml of a saturated solution of sodium
sulfate and 20 ml of diethyl ether were carefully added,
the organic phase was separated, and the aqueous
phase was extracted with methylene chloride (2×
10 ml). The extracts were dried over MgSO4 and
evaporated, and the solid residue was recrystallized
from chloroform–hexane (2:1). Yield 0.74 g (80%),
14. Gribble, G.W., Leese, R.M., and Evans, B.E., Synthesis,
1977, p. 172.
15. Razin, V.V., Zolotarev, R.N., Yakovlev, M.E., Kostryu-
kov, S.G., and Vasin, V.A., Russ. J. Org. Chem., 1996,
vol. 32, p. 1645.
16. Gaoni, Y. and Tomazic, A., J. Org. Chem., 1985, vol. 50,
p. 2948.
17. Wiberg, K.B. and Hess, B.A., J. Org. Chem., 1966,
vol. 31, p. 2250.
18. Günther, H., NMR Spectroscopy: an Introduction,
Chichester: Wiley, 1980. Translated under the title
Vvedenie v kurs spektroskopii YaMR, Moscow: Mir,
1984, p. 132.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 3 2008