Syntheses of 4- and 5-Chloro-cis-1,3-dimethylindanes

Abstract

Reaction of chlorobenzene with crotonic acid under Friedel-Crafts conditions gives an unexpectedly high proportion of 4-chloro-3- methylindan-1-one together with the expected 6-chloro-3-methylindan-1- one. Hydrogenolysis of the tertiary alcohols which result from addition of methylmagnesium iodide to these compounds gives predominantly cis-4- and -5-chloro-1,3-dimethylindanes with only small amounts of the trans- isomers.