MECHANISTIC ASPECTS OF THE C-H ALKYNYLATION REACTION OF ACETYLENIC TRIFLONES - DETERMINATION OF PHENYL VERSUS CYCLOHEXYL MIGRATORY APTITUDEFOR A VINYLIDINE CARBENE

C-13-2 labeled phenyl ethynyl triflone undergoes regiospecific C-H alk ynylation upon reaction with cyclohexane. The C-13 label is found to b e exclusively adjacent to the phenyl group in the product phenyl cyclo hexyl acetylene, consistent with cyclohexyl radical addition at the al pha-position. Control studies show preferential phenyl migration from a vinylidine carbene, thus excluding the presence of such an intermedi ate. Copyright (C) 1996 Elsevier Science Ltd