Manganese(I)-Catalyzed Site-Selective C6-Alkenylation of 2-Pyridones Using Alkynes via C-H Activation

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 CH2Cl2 at increased catalyst and additive loadings. Mechanistic studies suggest the involvement of a five-membered organomanganese as the key intermediate in the catalytic cycle.

Automated summary

A Mn(I)-catalyzed chelation-assisted direct C6-H alkenylation of 2-pyridones with both terminal and internal alkynes has been developed, leading to high yields of the products. Mechanistic studies indicate the involvement of a five-membered organomanganese as the key intermediate.