Intramolecular cyclization of s-phenyl 3-arylpropynethioates by the action of bronsted and lewis acids

Full text of DOI:10.1134/S1070428011040282

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 4, pp. 619–621. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © D.S. Ryabukhin, A.V. Vasil’ev, E.V. Grinenko, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 4,
pp. 612–614.
SHORT
COMMUNICATIONS
Intramolecular Cyclization of S-Phenyl 3-Arylpropynethioates
by the Action of Brønsted and Lewis Acids
D. S. Ryabukhin, A. V. Vasil’ev, and E. V. Grinenko
St. Petersburg State Academy of Forestry Engineering, Institutskii per. 5, St. Petersburg, 194021 Russia
e-mail: aleksvasil@mail.ru
Received December 22, 2010
DOI: 10.1134/S1070428011040282
Intramolecular cyclization of N,3-diarylpropyn-
amides or phenyl 3-arylpropynoates in various acidic
systems is used for the synthesis of quinoline [1] or
coumarin derivatives [2]. The present communication
reports on the transformations of S-phenyl 3-arylpro-
pynethioates Ia and Ib by the action of Brønsted
to thiocoumarin IIa (run no. 5), but the yield of IIa
was lower (60%) than in the reactions catalyzed by
Brønsted acids.
The transformation of propynethioate Ia in the
presence of AlCl gave not only cyclization product
3
IIa but also isomeric S-phenyl 3-chloro-3-phenylprop-
2-enethioates E-III and Z-III (run no. 6). The latter are
formed via abstraction of chloride ion from associated
(
H SO , HSO F, CF SO H) or Lewis acids (AlCl ,
2 4 3 3 3 3
AlBr ), leading to the corresponding 4-aryl-2H-thio-
3
chromen-2-ones IIa and IIb through electrophilic
intermediates A (Scheme 1). The reaction conditions
and yields are given in table. S-Phenyl 3-phenylpro-
pynethioate (Ia) in sulfuric acid at 20°C was converted
in 5 h into 4-phenyl-2H-thiochromen-2-one (IIa) in
AlCl species by strong electrophile A (Scheme 2). It
should be noted that no analogous bromine-containing
3
products were detected in the reaction with AlBr
(run no. 5).
3
The product mixture obtained in run no. 6 could not
be separated by preparative chromatography on silica
gel, and it was analyzed by gas chromatography–mass
9
6% yield (run no. 1). The transformations of com-
pounds Ia and Ib in stronger acids (HSO F, CF SO H)
3
3
3
1
required a shorter time (1 h at 0–20°C), the yield being
spectrometry and H NMR. Theoretical calculation
fairly high (84–90%; run nos. 3, 4, 8). In HSO F at
(ChemDraw Ultra 10.0) of the chemical shifts of vinyl
protons in isomers E-III and Z-III gave a larger value
for the Z isomer (δcalc 6.80 ppm against 6.42 ppm for
the E isomer). Therefore, the isomer characterized by
larger experimental chemical shift of the vinyl proton
(δexp 6.88 ppm) was assigned Z configuration, and that
with δexp 6.68 ppm, E configuration.
3
–
75°C (reaction time 0.25 h) thiocoumarins IIa and
IIb were formed in poor yield, and the conversion of
initial compounds Ia and Ib was not complete (run
nos. 2, 7), in contrast to analogous transformations of
phenyl 3-arylpropynoates [2]. Such Lewis acid as
AlBr also promoted intramolecular cyclization of Ia
3
Scheme 1.
R
O
H
OH
S
+
H (acid)
S
2H+
–
R
R
S
O
Ia, Ib
A
IIa, IIb
R = H (a), Me (b).
6
19

6
20
RYABUKHIN et al.
Scheme 2.
Ph
O
SPh
H
O
H
AlCl , CH Cl
3
2
2
Ph
Ph
SPh
SPh
+
+
Ph
S
O
Cl
Cl
O
Ia
IIa
E-III
Z-III
Thiocoumarins constitute a poorly explored class of
organic compounds, and their syntheses by other meth-
ods were reported in a few publications [3–8].
The reaction mixture obtained as described above
in a or b was poured into 30 ml of ice water and ex-
tracted with chloroform (3×50 ml). The extracts were
combined, washed with water, a saturated solution of
sodium hydrogen carbonate, and water again, and
Initial S-phenyl 3-arylpropynethioates Ia and Ib
were prepared according to the procedure described in
9] by reaction of benzenethiol with 3-phenylpropyn-
dried over Na SO , the solvent was distilled off under
[
2
4
reduced pressure (water-jet pump), and the residue was
subjected to chromatographic separation on silica gel
using hexane–ethyl acetate as eluent. The yields are
given in table.
oic and 3-(4-methylphenyl)propynoic acids, respec-
tively, in methylene chloride in the presence of
N,N′-dicyclohexylcarbodiimide and a catalytic amount
of pyridine.
S-Phenyl 3-phenylpropynethioate (Ia). Yield 47%,
4-Phenyl-2H-thiochromen-2-one (IIa). Oily sub-
stance; published data: mp 100°C [3], 98°C [4].
H NMR spectrum, δ, ppm: 6.53 s (1H, 3-CH), 7.24–
–
1
mp 58–60°C [10]. IR spectrum, ν, cm : 2185 (C≡C),
1
1
1
690 (C=O). H NMR spectrum, δ, ppm: 7.36 t (2H,
Harom, J = 7.6 Hz), 7.44–7.47 m (6H, Harom), 7.52–
7.29 m (1H, Harom), 7.37–7.38 m (2H, Harom), 7.45–
1
3
7
.55 m (2H, Harom).
7.53 m (6H, Harom). C NMR spectrum, δ
C
, ppm:
1
24.76, 126.21, 126.27, 126.83, 128.60, 128.89,
S-Phenyl 3-(4-methylphenyl)propynethioate (Ib).
Yield 45%, mp 108–110°C. H NMR spectrum, δ,
ppm: 2.37 s (3H, Me), 7.16 d (2H, Harom, J = 13.9 Hz),
1
129.74, 130.58, 137.84, 138.30, 155.46, 184.52. Mass
spectrum, m/z (I , %): 238 (19) [M] , 210 (100),
1
+
rel
65 (25).
7
.34 d (2H, Harom, J = 13.9 Hz), 7.45–7.47 m (3H,
Harom), 7.52–7.55 m (2H, Harom). Found, %: C 76.11;
H 4.83. C H OS. Calculated, %: C 76.16; H 4.79.
4-(4-Methylphenyl)-2H-thiochromen-2-one (IIb).
Oily substance. H NMR spectrum, δ, ppm: 2.44 s (3H,
1
16
12
Me), 6.52 s (1H, 3-H), 7.23-7.30 m (5H, Harom), 7.46 t
4
-Aryl-2H-thiochromen-2-ones IIa and IIb (gen-
(
1H, Harom, J = 7.6 Hz), 7.51 d (1H, Harom, J = 7.7 Hz),
eral procedure). a. A solution of 0.2 mmol of com-
pound Ia or Ib in 2 ml of the corresponding Brønsted
acid (H SO , HSO F, or CF SO H) was stirred for
7
.57 d (1H, Harom, J = 8.4 Hz). Mass spectrum, m/z
+
(I , %): 252 (12) [M] , 224 (100), 208 (8). Found, %:
rel
2
4
3
3
3
C 76.21; H 4.76. C H OS. Calculated, %: C 76.16;
0
.25–5 h at –75 to 20°C (see table; run nos. 1–4, 7, 8).
16 12
H 4.79. M 252.06.
b. A solution of 30 mg (0.13 mmol) of compound
Ia and 280 mg (0.63 mmol) of AlBr in 5 ml of CH Cl
was stirred for 2 h at 20°C (see table, run no. 5).
S-Phenyl (E/Z)-3-chloro-3-phenylprop-2-ene-
thioates (III) were formed together with compound
3
2
2
Transformations of S-phenyl 3-arylpropynethioates Ia and Ib in various acid systems
Run no.
Initial compound no.
Reaction conditions
SO , 20°C, 5 h
Product (yield, %)
IIa (96)
1
2
3
4
5
6
7
8
Ia
Ia
Ia
Ia
Ia
Ia
Ib
Ib
H
2
4
HSO
HSO
3
3
F, –75°C, 0.25 h
F, 0°C, 1 h
Ia (80), IIa (14)
IIa (90)
CF
AlBr
AlCl
HSO
CF SO
3
SO
, CH
, CH
3
H, 20°C, 1 h
IIa (84)
3
2
Cl
Cl
2
, 20°C, 2 h
, 20°C, 2 h
IIa (60)
3
2
2
IIa (41), E-III (20), Z-III (38)
Ib (70), IIb (22)
IIb (86)
3
F, –75°C, 0.25 h
H, 20°C, 1 h
3
3
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 4 2011

INTRAMOLECULAR CYCLIZATION OF S-PHENYL 3-ARYLPROPYNETHIOATES
IIa in the reaction of 50 mg (0.2 mmol) of compound
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 4 2011