Exhaustive C-methylation of ketones by trimethylaluminium

Abstract

Trimethylaluminium in hydrocarbon solvent at 100-200º gem -dimethylates various ketones (and some aldehydes) to alkanes. gem -Dimethylated alkanes prepared by this method include 1,l- dimethylindane, 2,2-dicyclopropylpropane, 2,2-di- p -tolylpropane, 1-t-butyl-2,5-dichlorobenzene, 1,l-dimethylcycloheptane, 9,9-dimethyifluorene, 2,3-bis( p -methoxyphenyl)-2-methylpentane, 2,3- bis( p -methoxyphenyl)-2,4-dimethylpentane and 3,3-dimethylcholestane. Xanthenone and N -methyl-acridone are gem -dimethylated particularly easily. Anthrone, however, gives 9-methylanthracene.