Reaction of enamines with benzylidene ketones. Part II.

Abstract

The reaction between cyclohexanone enamines and a variety of benzylidene ketones gives a dihydropyran derivative in each case. The benzopyrans from reactions of 1 -piperidinocyclohexene with chalcone and with dibenzylideneacetone are unstable and on heating readily rearrange into isomeric enamino-ketones (6) and (10). Recyclisation of 2-phenyl-2-(2-piperidinocyclohex-2-enyl)ethyl styryl ketone (10) gives 1,4-diphenyl-7b-piperidinoperhydrocyclobuta[de]naphthalen-2-one (11).