Russian Journal of Organic Chemistry, Vol. 40, No. 9, 2004, pp. 1377–1378. Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 9, 2004,
pp. 1424–1425.
Original Russian Text Copyright © 2004 by Rudenko, Savechenkov, Vasil’ev.
SHORT
COMMUNICATIONS
Stereoselective Synthesis of Methyl 3,3-Diarylpropenoates
A. P. Rudenko, P. Yu. Savechenkov, and A. V. Vasil’ev
St. Petersburg State Academy of Forestry Engineering, Institutskii per. 5, St. Petersburg, 194021 Russia
Received January 23, 2004
We recently reported on an unusual low-tempera-
ture dimerization of methyl 3-(4-methylphenyl)pro-
pynoate (I), which involved intermediate formation of
cation A [1]. It seemed reasonable to estimate the
scope of the revealed reaction as applied to other
acetylene compounds, and (what is the most important)
to use the vinyl-like cations generated therefrom by
the action of HSO3F as addends to foreign organic
substrates. Such processes would provide a simple
synthetic route to various practically important com-
pounds. For this purpose, we examined reactions of
cation A with 2,3,5,6-tetramethylbenzenesulfonyl
fluoride (II, R = FSO2) and (2,3,5,6-tetramethyl-
phenyl)acetonitrile (III, R = NCCH2). These substrates
do not react with HSO3F but are characterized by
considerably different reactivities in electrophilic sub-
stitution processes.
The structure of compounds IV and V was deter-
1
19
mined on the basis of their IR, H and F NMR, and
mass spectra with account taken of published data for
structurally related compounds [1]. The reaction mix-
tures were separated by column chromatography on
silica gel using a 2–5% solution of ethyl acetate in
hexane as eluent. In the reaction of cation A with
compound II, the mixture contained dimerization
products of ester I.
Methyl (E)-3-(4-methylphenyl)-3-(4-fluorosul-
fonyl-2,3,5,6-tetramethylphenyl)propenoate (IV).
Ester I, 0.050 g (0.287 mmol), was added over a period
of 30 min to a solution of 0.068 g (0.316 mmol) of
compound II in 1.5 ml of HSO3F, cooled to –75°C.
After 15 min, the mixture was poured into 15 ml of
concentrated hydrochloric acid cooled to –60°C. The
mixture was extracted with chloroform (3×5 ml), the
combined extracts were washed with water, a saturated
aqueous solution of NaHCO3, and water again, dried
over Na2SO4, and evaporated under reduced pressure
(water-jet pump), and the residue was subjected to
column chromatography on silica gel. Yield 0.042 g
(38%), mp 130–132°C. IR spectrum, ν, cm–1: 1620
(C=C), 1720 (C=O). 1H NMR spectrum, δ, ppm: 2.22 s
Despite the presence of two ortho-methyl groups,
compounds II and III readily reacted with cation A
generated in situ from methyl 3-(4-methylphenyl)-
propynoate (I). The reactions were stereoselective, and
the products were the corresponding E isomers of
methyl 3,3-diarylpropenoates IV and V. However, the
yields of compounds IV and V differed considerably
due to difference in electron-acceptor properties of the
substituents in the aromatic substrates.
(6H, 2Me), 2.33 s (3H, Me), 2.57 d (6H, 2Me, JHF
=
2.0 Hz), 3.71 s (3H, OMe), 5.77 s (1H, CH=), 7.09–
HSO3F, –75°C
4-MeC6H4
COOMe
4-MeC6H4
C
CH COOMe
I
A
4-MeC6H4
COOMe
H
Me
II, III
–H+
Me
Me
R
Me
IV (38%), V (75%)
IV, R = FSO2; V, R = NCCH2.
1070-4280/04/4009-1377 © 2004 MAIK “Nauka/Interperiodica”
Rudenko
