An Oxidative [3+2+1] Cyclization of Enaminones and N-Alkenyl-2-pyrrolidinone: Access to Polysubstituted 4-Alkylated 1,4-dihydropyridines

An oxidative [3 + 2 + 1] cyclization of enaminones and N-alkenyl-2-pyrrolidinone is described for the synthesis of 4-alkylated 1,4-dihydropyridines (1,4-DHPs). By using terminal olefin as the C4 source of the 1,4-DHP skeleton, this synthetic strategy provides a series of 1,4-DHPs through a 1,1-difunctionalization/cyclization process. In this protocol, two C(sp(3))-C(sp(2)) bonds and a C(sp(2))-N bond are simultaneously formed, the hydrogen source on the newly formed methyl group of the 1,4-DHP skeleton is confirmed and a possible mechanism is proposed.

Automated summary

This study describes an oxidative [3 + 2 + 1] cyclization reaction between enaminones and N-alkenyl-2-pyrrolidinone for the synthesis of 4-alkylated 1,4-dihydropyridines (1,4-DHPs). By using terminal olefin as the C4 source of the 1,4-DHP skeleton, this synthetic strategy allows for the formation of a series of 1,4-DHPs through a 1,1-difunctionalization/cyclization process. The formation of two C(sp(3))-C(sp(2)) bonds and a C(sp(2))-N bond simultaneously and the confirmation of the hydrogen source on the newly formed methyl group of the 1,4-DHP skeleton are discussed, along with a proposed mechanism.