Rearrangements of 8-chloro-8-methylbicyclo[4.2.0]oct-2-en-7-one

Abstract

The endo- and exo-methyl isomers of 8-chloro-8-methylbicyclo[4.2.0]oct-2-en-7-one were separately treated with aqueous sodium carbonate, aqueous sodium hydroxide, silver nitrate in methanol, and sodium methoxide in methanol. A stereospecific ring contraction and an allylic substitution involving the enol form of the bicyclic ketone were found to be dependent on the base. Thermal rearrangement of the title compound resulted in the formation of propiophenone.