Convenient Approach to 10-and 11-Membered Azalactams

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.

Automated summary

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 the bicyclic dihydropyrimidones depends on the ring size of the 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. The obtained medium ring azalactams with a secondary amine function were used in the synthesis of bicyclic heteroaromatic systems.