Preparation and reaction of phenylsulfonyl-substituted dizinciomethane

Article abstract of DOI:10.1246/cl.2007.864

Treatment of dibromomethyl phenyl sulfone with zinc powder in the presence of a catalytic amount of lead in THF afforded phenylsulfonyl-substituted dizinciomethane. The species converts a ketone or aldehyde into an alkenyl sulfone via a Wittig-type olefination reaction with the assistance of β-TiCl₃. Copyright

Full text of DOI:10.1246/cl.2007.864

864
Chemistry Letters Vol.36, No.7 (2007)
Preparation and Reaction of Phenylsulfonyl-substituted Dizinciomethane
Yoko Baba,1 Akio Toshimitsu,1 and Seijiro Matsubaraꢀ2
1International Innovation Centre, Kyoto University, Kyoutodaigaku-katsura, Nishikyo-ku, Kyoto 615-8510
2Department of Material Chemistry, Graduate School of Engineering, Kyoto University,
Kyoutodaigaku-katsura, Nishikyo-ku, Kyoto 615-8510
(Received April 25, 2007; CL-070452; E-mail: matsubar@orgrxn.mbox.media.kyoto-u.ac.jp)
Treatment of dibromomethyl phenyl sulfone with zinc
PhSO2CH(ZnL)2
2
powder in the presence of a catalytic amount of lead in THF
afforded phenylsulfonyl-substituted dizinciomethane. The spe-
cies converts a ketone or aldehyde into an alkenyl sulfone via
a Wittig-type olefination reaction with the assistance of ꢀ-TiCl3.
THF
1H NMR
in THF-d8
at 25 °C
Vinyl sulfones have been frequently used as intermediates in
organic synthesis, as the highly electron-withdrawing property
of sulfonyl group makes the alkenyl moiety highly electrophil-
ic.1 In addition, the sulfonyl group itself can be converted into
various functional groups.2 Preparation of these sulfones has
been performed in various ways; for example, Horner–Emmons
reactions of a carbonyl compound and a sulfonyl-substituted
phosphonate carbanion,3a ꢀ-elimination of halosulphones,3b,3c
hydrozirconation of terminal alkynes followed by reaction with
sulfonyl chlorides,3d cerium(IV) ammonium nitrate mediated
oxidative addition of sulfinate and iodine to alkenes,3e and the
Mizoroki–Heck reaction of arylboronic acids with phenyl vinyl
sulfones3f are available. Among them, Horner–Emmons reac-
tions are attractive, as the use of various ketones and aldehydes
will give a chance to prepare a variety of vinyl sulfones. Howev-
er, a lack of nucleophilicity of a stable sulfonyl-substituted phos-
phonate carbanion creates a limitation to this method. During
our course of studies on gem-dizinc species,4 we found that
the species performs Wittig-type olefination reactions under
the mediation of titanium salt.5 Because the reactivity of gem-di-
zinc species, which has a carbon substituted with two electropos-
itive zinc atoms, is much higher than the normal alkylmonozinc,
the olefination proceeds to an easily enolizable ketone, such as
ꢀ-tetralone. Thus, the preparation of sulfone-substituted gem-
dizinc species may give a useful alternative for the preparation
of vinyl sulfones from carbonyl compounds (eq 1).
PhSO2CH2(ZnL)
3
PhSO2CH3
4
Figure 1. 1H NMR spectra of the reaction mixture from dibro-
mide 1 (2.0 mmol) and Zn powder (5.0 mmol) in THF-d8
(4.0 mL) at 25 ꢁC (eq 2).
was 89/11. Figure 1 shows the 1H NMR spectra of the solution,
which was obtained from 2.0 mmol of dibromide, 6.0 mmol of
zinc powder, and 4.0 mL of THF-d8. The complex signal at ꢁ
1.2–2.2 was supposed to be from dizinc reagent 2, as an
addition of acetic acid little by little to the obtained mixture
converted the signal into the monozinc species 3 and methyl
phenyl sulfone 4. This result means that the complex signal came
from dizinc species 2 (eq 2 and Figure 1). The concentration
of 2 was determined by an integration of these complex signals
using an internal standard.
Zn (Pb)
PhSO2CHBr2
PhSO2CH(ZnBr)2
PhSO2CH(ZnL)2
THF
1
2a
2
Mtl
R'
R'
CH3CO2H
PhSO2CH2(ZnL)
PhSO2CH3
+
(2)
+
(1)
SO2Ph
PhSO2
R
Mtl
3
4
O
R
The complex signal of 2 can be rationalized as follows:
The initially formed bis(bromozincio)methyl phenyl sulfone
(2a) will form sulfone-substituted polymethylene zinc species
via the Schlenk equilibrium.8 As the formed oligomeric species
5 includes chiral centers as shown in eq 3, each species would
have a number of diastereomers. As a result, the species will
show a complex signal.
Phenylsulfonyldibromomethane (1) was prepared from bro-
moform and sodium phenylsulfinate by a modification of the
reported method.6 Zinc powder7 (90 mmol) and THF (3.0 mL)
was sonicated for 15 min using an ultrasonic cleaner bath under
Ar atmosphere. Dibromide (1, 30 mmol) in THF (27 mL) was
added dropwise over 40 min to the suspension at 0 ꢁC under
Ar atomosphere. The exothermic reaction began immediately.
After the whole mixture was stirred for 4 h at 25 ꢁC, it was left
to stand without stirring. The sedimentation of excess zinc
powder gave a pale yellow solution. The supernatant was used
as a solution of dizinc species in THF. Treatment of the dizinc
solution with 1 M DCl in D2O gave a mixture of PhSO2CD2H
and PhSO2CDH2. Their molar ratio, which was determined by
an integration of the 1H NMR signal at phenyl and methyl group,
+ PhSO2CH(ZnBr)
2
PhSO2
− ZnBr
− ZnBr
2
2
2 PhSO2CH(ZnBr)2
BrZnCHZnCHZnBr
PhSO2
+ ZnBr
− PhSO2CH(ZnBr)
2
2
2a
+ ZnBr
2
PhSO2
PhSO
PhSO2
2
(3)
BrZn–CHZn–CH
ZnBr
BrZnCHZnCH
ZnCHZnBr
n
PhSO2
5
PhSO2
Copyright Ó 2007 The Chemical Society of Japan

Chemistry Letters Vol.36, No.7 (2007)
865
Table 1. Preparation of vinyl sulfone from carbonyl com-
pounds and dizinc 2 under an assistance of various mediatorsa
References and Notes
1
2
3
M. C. Carreno, Chem. Rev. 1995, 95, 1717.
P. L. Fuchs, T. F. Braish, Chem. Rev. 1986, 86, 903.
R
H
Additive
RR'C=O (6)
THF, 25 °C
a) I. C. Popoff, J. L. Denver, J. Org. Chem. 1969, 34, 1128.
b) J. Sinnreich, M. Asscher, J. Chem. Soc., Perkin Trans. 1
1972, 1543. c) P. B. Hopkins, P. L. Fuchs, J. Org. Chem.
1978, 43, 1208. d) D.-H. Duan, X. Huang, Synlett 1999, 317.
e) V. Nair, A. Augustine, T. G. George, L. G. Nair, Tetra-
hedron Lett. 2001, 42, 6763. f) G. W. Kabalka, S. K. Guchhait,
Tetrahedron Lett. 2004, 45, 4021.
PhSO CH(ZnL)
2
2
THF, 25 °C
SO2Ph
R'
2
7
Run
RR0C=O (6)
2/equiv.
Additive/equiv.
7/%
1
2
Cyclohexanone
1.0
2.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
4.0
ꢀ-TiCl3 (1.0)b
ꢀ-TiCl3 (2.0)
ꢀ-TiCl3 (4.0)
13 (7a)
40 (7a)
59 (7a)
3
4
ꢀ-TiCl3 (4.0), ZnI2 (4.0) 88 (7a)
4
5
a) S. Matsubara, in Handbook of Functionalized Organo-
metallics Vol. 2, ed. by P. Knochel, Wiley-VCH, Weinheim,
2005, Chap. 8. b) H. Yoshino, N. Toda, M. Kobata, K. Ukai,
K. Oshima, K. Utimoto, S. Matsubara, Chem. Eur. J. 2006,
12, 721. c) S. Matsubara, K. Oshima, K. Utimoto, J. Organo-
met. Chem. 2001, 617–618, 39. d) S. Matsubara, K. Oshima,
Proc. Jpn. Acad. 2003, 79, 71.
a) S. Matsubara, K. Oshima, in Modern Carbonyl Olefination,
ed. by T. Takeda, Wiley-VCH, Weinheim, 2004, Chap. 5,
pp. 200–222. b) S. Matsubara, T. Mizuno, T. Otake, M.
Kobata, K. Utimoto, K. Takai, Synlett 1998, 1369.
5
PhCHO
—
0
.
6
BF3 OEt2 (2.0)
0
7
TiCl4 (2.0)
4 (7b)c
56 (7b)c
8
ꢀ-TiCl3 (2.0)
9
ꢀ-TiCl3 (4.0), ZnI2 (4.0) 59 (7b)c
ꢀ-TiCl3 (4.0), ZnI2 (4.0) 64 (7c)c
ꢀ-TiCl3 (4.0), ZnI2 (4.0) 36 (7d)c
ꢀ-TiCl3 (4.0), ZnI2 (4.0) 54 (7e)d
ꢀ-TiCl3 (4.0), ZnI2 (4.0) 40 (7f)d
10
3-Phenylpropanal
11 t-Butyl methyl ketone
12
13
2-Dodecanone
ꢂ-Tetoralone
aAll reactions were examined using 1.0 mmol carbonyl compound 6. See
b
Ref. 9. ꢀ-TiCl3 was prepared from TiCl4 and hexamethyldisilane accord-
6
7
W. Middelbos, J. Strating, B. Zwanenburg, Tetrahedron Lett.
1971, 12, 351.
ing to the repoted method. See Ref. 10. cOnly E isomer was formed diaster-
eoselectively. See Ref. 11. dThe product was obtained as a mixture of E and
Z isomers (ca. 1/1).
Pyrometallurgy zinc (Wako Chemical) was used. It contains
0.04–0.07% lead (Pb) originally. A combination of pure zinc
powder and catalytic amount of PbCl2 (0.05 mol %) was also
possible to be used. See: K. Takai, T. Kakiuchi, Y. Kataoka,
K. Utimoto, J. Org. Chem. 1994, 59, 2668.
A Wittig-type olefination using 2, which is the typical
reaction of a gem-dizinc reagent, will transform carbonyl
compounds into vinyl sulfones. As shown in Table 1, ketones
and aldehydes were treated with dizinc 2 in the presence of
various additives. A combination of ꢀ-TiCl3 and ZnI2 was effec-
tive mediator for this transformation. In our previous report
concerning methylenation of ketones using bis(iodozincio)-
methane, ꢀ-TiCl3 was an effective Lewis acid. In the present
system, we also supposed that ꢀ-TiCl3 works as an activator
of carbonyl compounds. An addition of ZnI2 was expected to
be an activator of polymeric reagent 2. Considering the Schlenk
equilibrium, an addition of zinc salt may shift the equilibrium to
break up the oligomer. It is notable that a bulky ketone (Run 11)
and a highly enolizable ketone (Run 13) were also transformed
into the corresponding vinyl sulfones.
8
9
Bis(iodozincio)methane can be prepared as a monomeric
CH2(ZnI)2 in THF solution (ca. 0.5 M). The structure in solu-
tion was studied using neutron scattering; See: S. Matsubara,
K. Oshima, H. Matsuoka, K. Matsumoto, K. Ishikawa, E.
Matsubara, Chem. Lett. 2005, 34, 952. An attempt to prepare
2a as the monomeric form under diluted condition also resulted
in the formation of the oligomeric form shown in eq 3.
To a suspension of ꢀ-TiCl3 (4.0 mmol) in THF (4 mL), a
solution of dizinc 2 (0.7–0.85 M, 4.0 mmol) and a solution of
ZnI2 (4.0 mmol) in THF (3.0 mL) was added successively
at 25 ꢁC. After the resulting mixture was stirred for 10 min,
carbonyl compound (1.0 mmol) in THF (1.0 mL) was added.
The whole was stirred for 4 h. After a typical aqueous
work-up, the obtained crude product was purified by silica-
gel column chromatography.
The prepared phenylsulfonyl-substituted gem-dizinc was
a stable reagent, which can be stored as a THF-solution in
a sealed bottle for at least a month. It also has a chance to
be a new synthetic tool for preparation of organic sulfone
compounds.
10 A. R. Hermes, G. S. Girolami, Inorg. Synth. 1998, 32, 309.
11 7b: (1H NMR in CDCl3) ꢁ 7.91–7.97 (m, 2H), 7.69 (d,
J = 15.6 Hz, 1H), 7.37–7.67 (m, 8H), 6.87 (d, J ¼ 15:6 Hz,
1H). 7d: (1H NMR in CDCl3) ꢁ 7.87–7.95 (m, 2H), 7.4–7.7
(m, 3H), 6.27 (q, J ¼ 1:2 Hz, 1H), 2.09 (d, J ¼ 1:2 Hz, 3H),
1.07 (s, 9H).
This work was supported financially by the Japanese
Ministry of Education, Culture, Sports, Science and Technology
and by Kyoto University, International Innovation Centre.
Published on the web (Advance View) June 9, 2007; doi:10.1246/cl.2007.864