Direct Electrophilic C-H Alkynylation of Unprotected 2-Vinylanilines

Unprotected aromatic amines can be used as directing groups in metal-catalyzed C-H alkynylations of alkenes. By using low amounts of an Ir^III catalyst in combination with alkynylbenziodoxolones as electrophilic alkyne-transfer reagents, highly desirable 1,3-enynes were isolated in excellent yields of up to 98 % with Z stereoselectivity. A broad substrate scope as well as the high synthetic utility of the 1,3-enynes render this new method an efficient approach for the synthesis of five- and six-membered heterocycles. Further derivatizations of the 1,3-enynes to highly substituted quinolines through Au^I - and N-bromosuccinimide-mediated exo-dig cyclizations were demonstrated.