Stereo-selective synthesis of complex dienes and eneynes by sequential hydroarylation and olefinic C–H functionalization

Abstract

We present a stereo-selective preparation of multi-substituted dienes and eneynes by sequential hydroarylation of internal alkynes via five-membered rhodacycle and olefinic C–H functionalization, including alkenylation, alkynylation and allylation through seven-membered endo-cyclopalladation, both enabled by the N,N-bidentate chelation assistance of pyrazinamide or picolinamide. The robustness and generality of the protocol have been demonstrated by the smooth conversion of a wide range of benzyl amides to afford up to 92% yields with E/Z ratio selectivity up to >99/1, as well as a successful gram-scaled synthesis. Further chemical derivations and photophysical properties of products were also examined.