Manganese(I)‐Catalyzed Site‐Selective C6‐Alkenylation of 2‐Pyridones Using Alkynes via C−H Activation
Shanhong Wan, Zhenli Luo, Xin Xu, Haiyang Yu, Jiajie Li, Yixiao Pan, Xin Zhang, Lijin Xu, Rui Cao
Abstract
Abstract A Mn(I)‐catalyzed chelation‐assisted direct C6−H alkenylation of 2‐pyridones with both terminal and internal alkynes in a highly regio‐ and stereo‐selective manner has been developed. The catalytic system consisting of Mn(CO) 5 Br catalyst and KOAc additive allows 1‐(2‐pyridyl)‐2‐pyridones to undergo alkenylation with various terminal alkynes in methyl tert ‐butyl ether (MTBE) to furnish the C6‐alkenylated 2‐pyridone products in high yields, and the alkenylation with internal alkynes occurs in CH 2 Cl 2 at increased catalyst and additive loadings. Mechanistic studies suggest the involvement of a five‐membered organomanganese as the key intermediate in the catalytic cycle. magnified image