Res. Chem. Intermed.
, Vol. 28, No. 4, pp. 337–342 (2002)
Also available online - www.vsppub.com
Intermediacy of bicyclo[2.2.1]hepteneone in the photolysis
and DAVIS MALIAKAL
Organic Chemistry Division, Regional Research Laboratory (CSIR), Trivandrum 695 019, India
Received 17 July 2000; accepted 15 February 2002
Abstract—UV Irradiation of cyclohexane solution of bicyclo[2.2.2]octenediones led to facile extru-
sion of carbon monoxide to give substituted dihydrobiphenyls along with the dehydrogenated prod-
ucts. The inseparable mixtures on DDQ oxidation afforded the biphenyl derivatives. Isolation of an
intermediate arising from the initial monodecarbonylation lends support to a proposed mechanistic
: 1,2-diones; photolysis; substituted biphenyls.
Photoextrusion of carbon monoxide from cyclic ketones is one of the earliest ex-
trusion reactions known. It has been the subject of numerous mechanistic studies
and has found some synthetic applications [1– 8]. Photolytic double decarbony-
lation of 1,2-diones has also been the subject of detailed investigations [9 –13].
Our own studies have shown that the photolytic double decarbonylation of bi-
cyclo[2.2.2]octenediones, easily obtainable by the Diels-Alder cycloaddition of
-quinones and acetylenes, offers a convenient route to the synthesis of highly sub-
stituted biphenyls and indene derivatives . In continuation of these studies we
have carried out the photolysis of the bicyclic diones derived from the cycloaddition
of the 1,2-diones and styrenes . The results of our studies with some implica-
tions on the mechanism of the photolysis are presented here. In an earlier study,
Liao and Ueng have examined the photolysis of benzobicyclo[2.2.2]octenediones
and have made a detailed mechanistic postulate .
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