Synthesis of 2,3-disubstituted pyrroles and pyridines from 3-halo-1-azaallylic anions

A new synthesis of 2,3-disubstituted pyrroles and pyridines:,is described. The reaction of 3-halo-1-azaallylic carbanions, regiospecifically generated from alpha -halogenated ketimines, with omega -iodoazides led to the regio specific formation of omega -azido-alpha -haloketimines. Treatment of these functionalized imines with tin(II) chloride afforded halogenated five-and six-membered cylic imines, which were transformed under mild conditions int o 2,3-disubstituted pyrroles and pyridines. The stereoselective reduction o f 2,3-dialkyl-3-chloro-1-pyrrolines to afford cis-2,3-dialkyl-3-chloropyrro lidines is also reported.