o-Quinonoid compounds. Part IV. 1,3-Diphenylinden-2-one
Abstract
1,3-Diphenylinden-2-one is generated by dehydration of 1-hydroxy-1,3-diphenylindan-2-one with acetic an-hydride, and by reduction of 1,3-dibromo-1,3-diphenylindan-2-one with sodium iodide. It is a reactive intermediate readily intercepted in Diels–Alder reactions with dienophiles and dienes. It dimerises below 20° by apparent [π4 +π4] addition but does not react with dienes in this way. Thermal dissociation of the dimer is a convenient source of 1,3-diphenylinden-2-one, which reacts stereospecifically with dimethyl maleate and dimethyl fumarate.