A Vinyl-Cation-Induced 1,3-Aryl Shift.

A net insertion of an unactivated, internal alkyne into a sp -sp C-C bond of simple benzylic alcohols was achieved using the rearrangement of a highly reactive vinyl cation intermediate to a stabilized allyl cation as the driving force for an unusual 1,3-carbon shift reaction. In the presence of 10 mol % of Al(OTf) as a simple, inexpensive, and abundant catalyst, high selectivity for the rearrangement was achieved. The reaction scope proved general with regard to both the alkyne and the benzylic alcohol and a range of 1,2-dihydroquinolines as well as 2H-chromenes were obtained.