Cycloadditions of arylketens to 1,1-dimethylallene, and thermal isomerisation of a 2-methylenecyclobutanone adduct to a 2-isopropylidenecyclobutanone

Abstract

1,1-Dimethylallene adds to diphenylketen to yield the cyclobutanones (1) and (2), whilst phenylchloroketen gives the related adducts (3) and (4): the 2-methylenecyclobutanone (1) is converted thermally into the isomer (2)via the intermediate (7).