Nickel-catalyzed arylative cyclization of 1,6-enynes: arylation of unactivated alkene moieties†

Abstract

We developed catalytic cyclization of 1,6-enynes, whereby an aryl group is introduced at an unactivated alkene moiety. The reaction of a 1,6-enyne with an arylboronic acid in the presence of an Ni(cod)₂/P(4-MeOC₆H₄)₃ complex yields a five-membered ring product incorporating an all-carbon quaternary center. Experimental studies and extensive DFT calculations reveal that an Ni(i) species is involved in the catalytic cycle, which is an uncommon pathway involving transmetalation, oxidative cyclization, selective sp³–sp² carbon–carbon bond formation, and finally hydrolysis.