MESROPYAN et al.
374
dithiols with oxiranes underlie procedures for the
preparation of artificial fibers [10], branched transport
molecules [11, 12], molecular glasses [13, 14], poten-
tial biologically active substances [15, 16], etc.
2.9 g (70%), nD20 = 1.5780. IR spectrum, ν, cm–1: 3010,
1605 (C=Carom), 1770 (C=O, lactone), 1740 (C=O,
1
ester). H NMR spectrum, δ, ppm: 0.88 m (6H, CH3,
pentyl), 1.10–2.25 m (22H, CH3CH2O, CH2), 2.46 m
and 2.67 m (2H each, 3-H), 3.10–3.40 m (4H, CH2S),
4.20 m (4H, OCH2), 4.63 m (2H, 2-H), 7.40–7.60 m
(8H, Harom). Found, %: C 65.03; H 54.10; S 8.99.
C38H50O8S2. Calculated, %: C 65.30; H 18.31; S 9.18.
The present communication reports on the reaction
of diethyl 2-alkyl-2-(oxiran-2-ylmethyl)malonates Ia
and Ib with sulfur-containing nucleophiles, biphenyl-
4,4′-dithiol (II), (biphenyl-4,4′-diyl)dimethanethiol
(III), and (2,4,6-trimethylbenzene-1,3-diyl)dimethane-
thiol (IV). The effects of different factors, such as
temperature, solvent, reaction time, and reactant ratio,
on the process were studied with a view to optimize
the reaction conditions. The oxirane ring in compounds
Ia and Ib was opened according to the Krasuskii rule
[17] with formation of the corresponding alcohols
which underwent cyclization under reduced pressure to
form butano-4-lactones V–VII (Scheme 1). The reac-
tions were carried out on heating in ethanol in the pres-
ence of pyridine, the reactant ratio I-to-(II–IV) being
2:1. Insofar as the initial oxiranes were racemates,
compounds V–VII were formed as mixtures of dia-
stereoisomers; in addition, the cyclization gave rise to
new chiral centers. As a result, overlapping multiplet
4,4′-Bis(4-ethoxycarbonyl-4-isopentyl-5-oxo-
tetrahydrofuran-2-ylmethylsulfanyl)biphenyl (Vb).
Yield 2.7 g (65%), nD24 = 1.5736. IR spectrum, ν, cm–1:
3010, 1605 (C=Carom), 1770 (C=O, lactone), 1740
(C=O, ester). 1H NMR spectrum, δ, ppm: 0.96 m [12H,
(CH3)2CH], 1.23 m (6H, CH3CH2O), 1.10–1.80 m
(6H, CHCH2CH2), 1.90–2.20 m (4H, 4-CH2), 2.45 m
and 2.68 m (2H each, 3-H), 3.15–3.45 m (4H, CH2S),
4.19 m (4H, OCH2), 4.61 m (2H, 2-H), 7.40–7.60 m
(8H, Harom). Found, %: C 65.59; H 18.44; S 8.91.
C38H50O8S2. Calculated, %: C 65.30; H 18.21; S 9.18.
4,4′-Bis(4-ethoxycarbonyl-5-oxo-4-pentyltetra-
hydrofuran-2-ylmethylsulfanylmethyl)biphenyl
(VIa). Yield 3.5 g (85%), nD25 = 1.5603. IR spectrum, ν,
cm–1: 3010, 1605 (C=Carom), 1780 (C=O, lactone),
1735 (C=O, ester). 1H NMR spectrum, δ, ppm: 0.90 m
(6H, CH3, pentyl), 1.05–2.15 m (22H, CH3CH2O,
CH2), 2.40 m and 2.64 m (2H each, 3-H), 2.77 m (4H,
2-CH2), 3.81 s (4H, SCH2), 4.20 m (4H, OCH2),
4.59 m (2H, 2-H), 7.30–7.60 m (8H, Harom). Found, %:
C 65.81; H 7.79; S 9.09. C40H54O8S2. Calculated, %:
C 66.09; H 7.49; S 8.82.
1
signals were observed in their H NMR spectra. The
structure of compounds V–VII was confirmed by the
IR and 1H NMR spectra and elemental analyses.
EXPERIMENTAL
1
The H NMR spectra were recorded from solutions
in DMSO-d6 on a Varian Mercury-300 spectrometer
(300 MHz) using hexamethyldisiloxane as internal
reference. The IR spectra were measured on UR-20
and Nicolet FTIR NEXUS spectrometers from thin
films. Initial diethyl 2-alkyl-2-(oxiran-2-ylmethyl)-
malonates Ia and Ib were synthesized according to the
procedure described in [18].
4,4′-Bis(4-ethoxycarbonyl-4-isopentyl-5-oxo-
tetrahydrofuran-2-ylmethylsulfanylmethyl)bi-
phenyl (VIb). Yield 3.7 g (88%), nD25 = 1.5643. IR
spectrum, ν, cm–1: 3010, 1605 (C=Carom), 1780 (C=O,
1
lactone), 1735 (C=O, ester). H NMR spectrum, δ,
ppm: 0.96 m [12H, (CH3)2CH], 1.29 m (6H,
CH3CH2O), 1.10–1.80 m (6H, CHCH2CH2), 1.80–
2.17 m (4H, 4-CH2), 2.39 m and 2.63 m (2H each,
3-H), 2.76 m (4H, 2-CH2), 3.80 s (4H, SCH2), 4.19 m
(4H, OCH2), 4.58 m (2H, 2-H), 7.30–7.60 m (8H,
Harom). Found, %: C 66.31; H 7.77; S 9.11. C40H54O8S2.
Calculated, %: C 66.09; H 7.49; S 8.82.
Butano-4-lactones V–VII (general procedure).
A mixture of 5.9 mmol of dithiol II–IV, 12 mmol of
ester Ia or Ib, 0.01 ml of pyridine, and 10 ml of
ethanol was heated for 5 h at 75–80°C. The solvent
was removed under reduced pressure, and the residue
was heated at 50–60°C to complete cyclization, dis-
solved in 20 ml of diethyl ether, and reprecipitated
with hexane. The viscous material was separated from
the solution, dried under reduced pressure, and purified
by column chromatography on Al2O3 using ethanol as
eluent. All compounds V–VII were isolated as undis-
tillable viscous substances.
2,6-Bis(4-ethoxycarbonyl-5-oxo-4-pentyltetra-
hydrofuran-2-ylmethylsulfanylmethyl)-1,3,5-tri-
methylbenzene (VIIa). Yield 2.1 g (51%), nD20
=
1.5300. IR spectrum, ν, cm–1: 3010, 1605 (C=Carom),
1
1790 (C=O, lactone), 1750 (C=O, ester). H NMR
spectrum, δ, ppm: 0.89 m (6H, CH3, pentyl), 1.10–
2.20 m (22H, CH3CH2O, CH2), 2.43 m and 2.66 m (2H
4,4′-Bis(4-ethoxycarbonyl-5-oxo-4-pentyltetra-
hydrofuran-2-ylmethylsulfanyl)biphenyl (Va). Yield
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 3 2012