TYPE I AND TYPE II PHOTOCHEMICAL REACTION OF ω-ISOBUTYRYL-ω-METHYL-2,3-BENZOCYCLOALK-2-EN-1-ONES.

Article abstract of DOI:10.1016/S0040-4020(01)87699-7

ω-Isobutyryl-ω-methyl-2,3-benzocycloalk-2-en-1-ones (6a-c) undergo both type I and type II photoreactions.The type I/type II product ratio depends on the ring size; the six-membered ketone 6a is subject to type II reaction and the eight-membered ketone 6c is subject to type I reaction predominantly.The cyclization/elimination ratio of the type II reaction of 6 also depends on the ring size; the ratio decreases with increasing ring size.