Convenient Approach to 10‐ and 11‐Membered Azalactams

Abstract

A convenient method for the synthesis of 10‐ and 11‐membered azalactams via reductive cleavage of bicyclic systems featuring an amidine fragment was studied. It was found that the ring‐expansion reaction of bicyclic dihydropyrimidones depends on the ring size of saturated fragment, substituents in the pyrimidone core and reaction conditions. A new efficient method for the synthesis of medium ring azalactams by reductive cleavage of quaternary salts of annulated dihydropyrimidones was proposed as well. The obtained medium ring azalactams with a secondary amine function were used in the synthesis of bicyclic heteroaromatic systems.