Mechanistic implications of photoannelation reaction of 4,4dimethyl-cyclohex-2-ene-1-one and acrylonitrile — regio and stereochemistry of the major photoadduct by 1H and 13C NMR spectroscopy

Abstract Using a variety of 1 H and 13 C one and two-dimensional NMR experiments the structure and stereochemistry of the major photoadduct from 4,4-dimethyl-cyclohex-2-ene-1-one and acrylonitrile has been characterized as 7-(exo)cyano-5,5-dimethyl-bicyclo[4.2.0]-octan-2-one. The preferred regioselectivity suggests the participation of transoid enone in the ground state in photoannelation with acrylonitrile.