[1,3]-vs.[1,2]-Sigmatropic photorearrangements in cyclic βγ-unsaturated ketones. Conversion of bicyclo[5,4,0]undec-1(7)-en-3-one into 6-methylene-spiro[4,5]decan-1-one
Abstract
Bicyclo[5,4,0]undec-1(7)-en-3-one is photoisomerised to 6-methylenespiro[4,5]decan-1-one via a singlet state whereas bicyclo[4,4,0]dec-1(6)-en-3-one yields tricyclo[4,3,1,01,6]decan-7-one via a triplet state.