Cyclization of (Z,Z)-1,4-bis-(alkylseleno)-1,4-diphenyl-1,3-butadienes to 2,5-diphenylselenophene [11]

Full text of DOI:10.1023/A:1011906521941

Chemistry of Heterocyclic Compounds, Vol. 37, No. 6, 2001
Z Z
CYCLIZATION OF ( , )-1,4-BIS-
(ALKYLSELENO)-1,4-DIPHENYL-
1,3-BUTADIENES TO
2,5-DIPHENYLSELENOPHENE
V. A. Potapov, S. V. Amosova, and I. V. Doron'kina
Keywords: (Z,Z)-1,4-bis(alkylseleno)-1,4-diphenyl-1,3-butadienes, 2,5-diphenylselenophene, cyclization.
We have observed a previously unknown reaction: conversion of (Z,Z)-1,4-bis(alkylseleno)-1,4-
diphenyl-1,3-butadienes 1a,b to 2,5-diphenylselenophene (2) and dialkyl selenides. On exposure to UV
radiation, compound 1a is converted to heterocycle 2 in 33% yield. Heating compounds 1a,b at 180°C in a
sealed ampul in chloroform solution leads to formation of heterocycle 2 in 52% (1a) and 30% (1b) yields. The
yields are calculated based on the amount of compounds 1a,b used, and are not optimized.
hν
RSeR
Ph
Ph
+
or 180jC
Ph
Se
Ph
RSe SeR
1a,b
2
1 a R = i-Pr, b R = Et
We may hypothesize that the reaction proceeds according to a radical chain mechanism. A possible
route for the formation of heterocycle 2 includes homolytic rupture of the Se–C bond in compounds 1a,b with
formation of the radical intermediate 3. The selenenyl radical 4 formed along with heterocycle 2 in the last step
of the process can react with the starting compounds 1a,b, yielding intermediate 3, which begins a new chain of
transformations.
.
–[R ]
Ph
Ph
Ph
Ph
R
.
Se Se
SeR
RSe
1a,b
–RSeR
3
1a,b
.
RSe
+
Ph
Ph
R
Ph
Se
2
Ph
Se Se
.
__________________________________________________________________________________________
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of Russian Academy of Sciences, Irkutsk
664033; e-mail: potapov@irioch.irk.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, p. 856,
June, 2001. Original article submitted April 15, 2001.
0009-3122/01/3706-0795$25.00©2001 Plenum Publishing Corporation
795

2,5-Diphenylselenophene (2); mp 171-172°C (corresponds to literature data [1]). Mass spectrum, m/z:
1
284 [M+·]. H NMR (CDCl3): 7.56 (4H, m, ortho); 7.44 (2H, s, CH); 7.36 (4H, m, meta); 7.28 (2H, m, para).
Found, %: C 68.03; H 4.34; Se 27.55. C16H12Se. Calculated, %: C 67.85; H 4.27; Se 27.88.
Compounds 1a,b have been synthesized by nucleophilic addition to diphenyldiacetylene of
alkaneselenolate anions generated under the process conditions from dialkyldiselenides according to the familiar
procedure in [2,3].
REFERENCES
1.
2.
3.
R. F. Curtis, S. N. Hasnain, and J. A. Taylor, J. Chem. Soc., Chem. Commun., 365 (1968).
V. A. Potapov and S. V. Amosova, Phosphorus, Sulfur, Silicon, 79, 277 (1993).
V. A. Potapov, S. V. Amosova, and I. V. Doron'kina, in: Abstracts, Third All-Russian Symposium on
Organic Chemistry [in Russian], Yaroslavl (2001), p. 86.
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