Photocycloelimination of α,α-dichlorocyclobutanones

Abstract

Direct irradiation of a series of α,α-dichlorocyclobutanones in benzene solutions results in photocycloelimination to give 1,1-dichloroalkenes in yields ranging from 30-65%. The α,α-dichlorocyclobutanones were formed in good yields from the [2+2] cycloaddition of the terminal olefins with dichloroketene. This two-step sequence formally represents a "metathesis" of two olefinic functions and provides an easy access to functionalized 1,1-dichloroalkenes. Irradiation of the dichlorocyclobutanones in the solid state led to poor yields of 1,1-dichloroalkenes and polymeric mixtures, however, photoreactions performed in zeolites gave similar yields as those run in benzene solutions.Key words: dichlorocyclobutanones, dichloroalkenes, olefin metathesis, photocycloelimination.