The chemistry of the tandem reaction of 1-aryltetrahydrobenzothieno[2,3-c] pyridines with activated alkynes

Full text of DOI:10.1007/s10593-010-0513-2

Chemistry of Heterocyclic Compounds, Vol. 46, No. 3, 2010
THE CHEMISTRY OF THE TANDEM REACTION OF
1-ARYLTETRAHYDROBENZOTHIENO[2,3-c]PYRIDINES
WITH ACTIVATED ALKYNES
1
1
1
1
L. G. Voskressensky *, T. N. Borisova , S. A. Kovaleva , L. N. Kulikova ,
1
2
1
A. V. Listratova , S. V. Tolkunov , and A. V. Varlamov
Keywords: benzothienopyridines, tandem reaction.
Complex reactions of 1,2,3-trisubstituted benzothieno[2,3-c]pyridines with activated alkynes occur in
methanol to form multicomponent mixtures from which products of cleavage of the tetrahydropyridine ring have
been identified [1]. We propose that this feature of the transformation is due to the formation of carbocations
(
stabilized by methyl groups) via cleavage of the C(1)–N bond in the intermediate ammonium
E
E
Me
–
N
E
E
–
N Me
+
E
E
N
Me
+
MeCN, 20°C
S
S
S
1
A
B
E
E
Me
N
H
N
N
H
E = CO Me
2
S
2
_
*
______
To whom correspondence should be addressed, e-mail: lvoskressensky@sci.pfu.edu.ru.
1
Peoples' Friendship University of Russia, Moscow 117198, Russia.
2
L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences
of Ukraine, Donetsk 83114, Ukraine; e-mail: stolkunov@yahoo.com.
_
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 447-449, March, 2010. Original
article submitted January 27, 2010.
54 0009-3122/10/4603-0354©2010 Springer Science+Business Media, Inc.
3

zwitterion [1]. In order to confirm this proposal we have carried out the reaction of the 1-phenyltetrahydro-
thieno-[2,3-c]pyridine 1 with acetylene dicarboxylic ester (ADCE) in the presence of indole as an acceptor of
the potential carbocation.
The main reaction product was the benzothiophene 2 obtained in 76% yield. Its formation confirms our
proposal. The zwitterion A is converted to the stable diaryl type carbocation B which is captured by the indole.
1
13
IR spectra (KBr) were recorded on an Infralum FT-801 Fourier spectrometer. H and C NMR spectra
were taken on a Bruker WP-400 instrument (400 and 100 MHz respectively) using CDCl and with TMS as
3
internal standard. Chromato-mass spectra were obtained on a system including an Agilent 1100 series liquid
chromatograph and an Agilent Technologies LC/MSD VL mass spectrometer using electrospray ionization
(
APCI, Sedex 75 ELSD).
Dimethyl (E)-2-[(2-{2-[1H-indol-3-yl(phenyl)methyl]-1-benzothien-3-yl}ethyl)(methyl)amino)but-
-ene Dicarboxylate (2). Indole (0.15 g, 2 mmol) and ADCE (0.47 g, 3.3 mmol) were added to a solution of the
2
benzothienopyridine 1 (0.3 g, 1.1 mmol) in acetonitrile (25 ml). The reaction was carried out at room
temperature for 30 days and was monitored using TLC. Solvent was evaporated and the residue was
chromatographed on aluminium oxide (neutral Brockmann 1) using ethyl acetate–hexane (1:5). Yield 76% as a
-
1
colorless oil with R 0.32 (Sorbfil, ethyl acetate–hexane, 1:2). IR spectrum, , cm : 1736 (CO), 1684 (CO).
H NMR spectrum, , ppm (J, Hz): 2.54 (3H, s, NCH
f
1
3 2 2
); 3.02-3.06 (1H, m, CH ); 3.14-3.19 (3H, m, CH ); 3.65
(
3H, s, CO CH ); 3.80 (3H, s, CO CH ); 4.54 (1H, s, =CHCO CH ); 6.05 (1H, s, CHAr ); 6.76 (1H, d, J = 1.6,
2
3
2
3
2
3
3
CHNH); 7.01-7.04 (1H, m, H Ar); 7.19 (1H, td, J = 1.1 and J = 7.7, H Ar); 7.27-7.40 (9H, m, H Ar); 7.70 (2H, t,
1
3
J = 7.7, H Ar); 8.09 (1H, br. s, CHNH). C NMR spectrum, , ppm: 25.7, 37.4, 42.3, 50.8, 52.5, 52.9, 84.6,
1
1
11.3, 118.8, 119.3, 119.7, 121.1, 122.4, 122.5, 123.9, 124.0, 124.1, 126.7, 127.0, 127.3, 128.6 (4C), 136.5,
39.0, 140.0, 143.0, 145.8, 154.4, 166.1, 168.0. LC-MS spectrum: [M+H] 539. Found, %: C 71.29; H 5.67;
+
N 5.29. C H N O S. Calculated, %: C 71.35; H 5.61; N 5.20. M 538.
3
2
30
2
4
This work was carried out with the financial support of the Russian Fund for Basic Research and the
Ukrainian National Academy of Sciences (grant 08-03-90451 Ukraine).
REFERENCES
1
.
L. G. Voskressensky, T. N. Borisova, A. V. Listratova, E. A. Sorokina, S. V. Tolkunov, and
A. V. Varlamov, Izv. Akad. Nauk, Ser. Khim., 1003 (2007).
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