Lithium aluminium hydride-mediated methylation of diphenylmethane and allied compounds by bis-2-(methoxyethyl) ether

Abstract

Diphenylmethane (1) yields mainly 1,1-diphenylethane or 2,2-diphenylpropane (10) upon heating with lithium aluminium hydride in bis-(2-methoxyethyl) ether, depending on the reaction conditions. Cyclic analogues of diphenylmethane are αα-dimethylated much faster than diphenylmethane itself under the same conditions. 1,1-Diphenylcyclopropane (11) is reduced to 2,2-diphenylpropane by lithium aluminium hydride on prolonged heating in bis-(2-methoxyethyl) ether. Evidence for the formation of the cyclopropane (11) as a by-product from diphenylmethane, bis-(2-methoxyethyl) ether, and lithium aluminium hydride is presented.