Mechanistic aspects of the C-H alkynylation reaction of acetylenic triflones. Determination of phenyl versus cyclohexyl migratory aptitude for a vinylidine carbene

Article abstract of DOI:10.1016/0040-4039(96)01117-3

¹³C-2 labeled phenyl ethynyl triflone undergoes regiospecific C-H alkynylation upon reaction with cyclohexane. The ¹³C label is found to be exclusively adjacent to the phenyl group in the product phenyl cyclohexyl acetylene, consistent with cyclohexyl radical addition at the α-position. Control studies show preferential phenyl migration from a vinylidine carbene, thus excluding the presence of such an intermediate.