PHOTOCHEMICAL BEHAVIOUR OF 3,4-EPOXYPRECOCENE-I AND RELATED EPOXYCHROMANS

Article abstract of DOI:10.1016/S0040-4020(01)89238-3

A systematic study of photochemical behaviour of 3,4-epoxyprecocene-I and related epoxychromans was undertaken.Upon irradiation in acetone or cyclohexane, 3,4-epoxyprecocene-I 1 was found to undergo photoisomerisation to the corresponding 3-chromanone 2.In contrast, the photochemical behaviour of analogous 3,4-dihydro-3,4-epoxy-2H-1-benzopyrans 3 was found to be dependent upon the nature of solvent.Irradiation of 3 in cyclohexane led to photodecarbonylation leading to the formation of 2,3-dihydrobenzofurans 4, whereas irradiation in acetone resulted in the formation of chromanones 5.