Synthesis of Regioisomeric Pyrido[ c ]azocanones from Azaindanone Derivatives

A ring enlargement reaction with methylamine gave new pyrido[2,3‐ c ]‐, pyrido[3,4‐ c ]‐ and pyrido[3,2‐ c ]azocanone derivatives from cyclic β‐oxo esters with a cyclopentapyridine skeleton and a 1,4‐diketone moiety. The starting materials for this ring transformation were either prepared from halogenopyridine carboxylates by Heck reaction and subsequent hydrogenation, or (halogenomethyl)pyridine carboxylates were submitted to S N reaction with diethyl malonate. Both routes were completed by Dieckmann condensation to build the cyclic β‐oxo ester structure and alkylation with phenacylbromide to install the 1,4‐diketone motif.