AcOH-Catalyzed Rearrangements of Benzo[][1,4]diazepin-2(and 3)-ones: Easy Access to 1,4-Dihydroquinazolines and Their Condensed Analogues.

Presented herein is a novel synthesis of new 2-(quinolin-4-yl)-1,4-dihydroquinazoline systems , in which the acid-catalyzed rearrangement of spiro[benzo[][1,4]diazepine-3,4'-quinolin]-2(1)-ones generated from 3-(2-aminophenyl)-5-benzo[][1,4]diazepin-2(1)-ones with acetone and alkylmethyl ketones has been realized as an important step. An attempt to synthesize isomeric 2-(2-aminophenyl)-5-benzo[][1,4]diazepin-3(4)-one by hydrolysis of the corresponding -{2-[5-benzo[][1,4]diazepin-3(4)-on-2-yl]phenyl}acetamide led to a new heterocyclic system, 6-methyl-8,13-dihydro-13a-quinazolino[4,3-]quinazolin-5-ium 13a-carboxylate , as a result of an unexpected rearrangement. In addition, it is noteworthy that during the hydrolysis of -{2-[5-benzo[][1,4]diazepin-2(1)-on-3-yl]phenyl}acetamides , the not previously described 14-dihydro-5-14,5a-(epimino[1,2]benzo)benzo[5,6][1,4]diazepin[2,1]quinazolin-6(7)-ones were unexpectedly obtained.