Photochemical Synthesis of Bicyclo[4.1.0]hept-2-enes
作者:Sadamu Katayama、Masashige Yamauchi
DOI:10.1246/cl.1995.311
日期:1995.4
Bicyclo[4.1.0]hept-2-enes (norcarenes) were obtained in good yield by photolysis of 3-methylthiomethyl or 3-(2-ethoxycarbonyl)vinylbicyclo[2.2.2]oct-5-en-2-ones in benzene upon high pressure Hg lamp irradiation.
Photochemical reaction of bicyclo[2.2.2[oct-5-en-2-ones has been
investigated as a prelude to focused application to the synthesis of
sesquiterpenes such as sesquicarene and sirenin. Diels–Alder
reaction of cyclohexa-2,4-dienes, having different substituents
(methylthiomethyl and methoxy) at the C-6 position, with a dienophile
proceeds regio- and stereo-selectively to give
bicyclo[2.2.2]oct-5-en-2-ones; their photolysis in benzene upon
high-pressure Hg lamp irradiation affords decarbonylation products,
bicyclo[4.1.0]hept-2-enes (trinorcarenes), stereoselectively.
Replacement of the methylthiomethyl group with a 2-ethoxycarbonylvinyl
group improves the sequential reaction.