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

The ortho-directed lithiation of 3-tert-butyl- or 3-tert-butoxycarbonylaminopyridines (3) with alkyllithiums and reaction with NN-diethylbenzamide followed by acid hydrolysis gave 3-amino-4-benzoylpyridine (6) in good yield. Reaction of BTBO with the glycine derivatives 70 b and then reaction with 6 afforded 3-alkoxycarbonylaminomethylcarbonylamino-4-benzoylpyridines 8a b. Acid-catalyzed hydrolysis and cyclization of 80 b yielded 9 which on methylation gave 13-dihydrol- methyl-5-phenyl-2H-pyrido[34-e]-14-diazepin-2-(o1n0e) in 36% overall yield from 30.