One‐Pot Synthesis of Tri‐ and Tetrasubstituted Pyridines by Sequential Ring‐Opening/Cyclization/Oxidation of N‐Arylmethyl 3‐Aziridinylpropiolate Esters

A novel strategy for the one‐pot synthesis of substituted pyridines from N‐arylmethyl 3‐aziridinylpropiolate esters is described. The method employs a three‐step procedure including the formation of allenyl imines, phosphine‐catalyzed cyclization, and subsequent oxidation of the dihydropyridines. Depending on the reaction conditions of the final oxidation step, tri‐ and tetrasubstituted pyridines can be selectively produced.