 Since its discovery, the Kröhnke synthesis has enjoyed broad applicability to the preparation of di-,tri- and tetrapyridine derivatives, demonstrating a number of advantages over related reactions such as the Hantzsch pyridine synthesis.The mechanism of the Kröhnke pyridine synthesis begins with enolization of α-pyridinium methyl ketone 4 followed by 1,4-addition to the α, β-unsaturated ketone 5 to form the Michael adduct 6, which immediately tautomerizes to the 1,5-dicarbonyl 7.Addition of ammonia to 7 followed by dehydration via 8 generates the imine intermediate 9., The imine intermediate is then deprotonated to enamine 10 and cyclizes with the carbonyl to generate intermediate 11.