An improved synthesis of 1,3-dihydro-1-methyl-5-phenyl-2H-pyrido[3,4-e]-1,4-diazepin-2-one via ortho-directed lithiation of 3-tert-butyl and 3-tert-butoxycarbonylaminopyridine

Abstract

The ortho-directed lithiation of 3-tert-butyl- or 3-tert-butoxycarbonylaminopyridines (3) with alkyllithiums and reaction with N,N-diethylbenzamide followed by acid hydrolysis gave 3-amino-4-benzoylpyridine (6) in good yield. Reaction of BTBO with the glycine derivatives 7a, b and then reaction with 6 afforded 3-alkoxycarbonylaminomethylcarbonylamino-4-benzoylpyridines 8a, b. Acid-catalyzed hydrolysis and cyclization of 8a, b yielded 9, which on methylation gave 1,3-dihydro-1-methyl-5-phenyl-2H-pyrido[3,4-e]-1,4-diazepin-2-one (10) in 36% overall yield from 3a.