Zincke's Reaction with Chiral Primary Amines: A Practical Entry to Pyridinium Salts of Interest in Asymmetric Synthesis

Abstract

The scope of Zincke's synthesis of pyridinium salts using various chiral primary amines and mono- or dialkylpyridines substituted at positions 3, 4 or 5 has been investigated. Salts 6a-f, 9a-i, and 10b,e,h-j were obtained in excellent yields. The results support the accepted mechanism for Zincke's reaction and shows the influence of the solvent on the course of this reaction.