Overcrowded molecules. Part V. Stereochemistry and stereospecific photochemical rearrangement reaction of 1,2-bisdiphenylmethylene-3-methylindane

Abstract

The stereochemistry of 1,2-bisdiphenylmethylene-3-methylindane is discussed, and evidence is presented that this severely overcrowded molecule undergoes photochemical ring closure by only one of the possible conrotatory modes, followed by a [1,5] hydrogen shift, to give 4b,5-dihydro-11-methyl-5,5,10-triphenylbenzo[b]fluorene having the methyl group anti to the 4b-hydrogen.