PHOTOLYSIS OF BICYCLO[5.2.1]DECAN-10-ONES

An investigation of the photolysis of bicyclo[5.2.1]decan-10-one (1) and l,7-dimethylbicyclo[5.2.1]-decan-10-one (16) has shown that, while the initial scission occurs between the carbonyl carbon and the α-carbon, the ensuing steps differ for the two ketones. Compound 1, containing α-hydrogens, undergoes transannular hydrogen migration to yield a ketene which, in turn, is susceptible to further photolysis and yields cis-cyclononene (4), cis-bicyclo[4.3.0]nonane (5), and cis-bicyclo[6.1.0]nonane (6). Compound 16, containing no α-hydrogens, undergoes decarbonylation to yield cis-1,7-dimethylbicyclo[5.2.0]nonane (18), 2,8-dimethylnona-l,8-diene, and a mixture of isomeric C11H2o monoolefins (19,20, 21). The monoolefins are thought to arise via initial production of a dimethylcyclononenecarboxaldehyde, formed via intramolecular hydrogen migration in the initially formed biradical 26. © 1968, American Chemical Society. All rights reserved.