Esters of P-aryl substituted acids (1) have been reported to undergo an oxygen rearrangement involving migration of one of the oxygen atoms of the carboxyl group to the unsaturated portion of the m ~ lecule . ~ ~ ~ ... Further investigation of a variety of carboxylic acid esters with similar structure revealed that for the oxygen rearrangement the alcohol residue should form a stable radical and the unsaturated group capable of playing the part of an electron donor should ...