Synthesis of novel cyclic sulfone dihydropyridines facilitated by a selective ethyl diazoacetate ring expansion

A series of novel cyclic sulfone dihydropyridines with five to nine membered rings have been synthesized. Anomalous intermediates isolated from the Hantzch condensation were found to vary depending on the sulfone ring size and aromatic substitution. Tin tetrachloride has been shown to be a superior Lewis acid catalyst for ethyl diazoacetate ring expansion of the requesite β-keto cyclic sulfone precursors.