Synthesis of Complex Eneynes by Selective α and β C−H Alkynylation of Aryl Alkenes

Comprehensive Summary Eneyne is one of the most prevalent building blocks in synthetic chemistry. Alkenyl C−H alkynylation affords an efficient synthesis of eneynes, however, the direct use of styrenes as the synthon has remained much unexplored so far. We present the first α‐/β‐C−H alkynylation of E ‐ and Z aryl alkenes as well as α‐substituted aryl alkenes, producing complex eneynes with excellent regio‐ and E / Z ratio selectivity, assisted by N , N ‐bidentate directing group under palladium catalysis. Notably, disubstituted E ‐aryl alkenes underwent α‐C−H alkynylation and then β‐C−H alkenylation to produce conjugated dieneynes. The robustness of the protocol was further demonstrated by the successful C−H conversion of substrates including 2‐alkenyl benzyl amides and anilides, proceeding by five‐ to seven‐membered endo ‐/ exo ‐palladacycles.