SYNTHESIS OF 1,2-DIAZEPINO[3,4-B]QUINOXALINES AND PYRIDO[3',4'-9,8][1,5,6]OXADIAZONINO[3,4-B]QUINOXALINES VIA A 1,3-DIPOLAR CYCLOADDITION REACTION

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 8 with furfural, 3-methyl-2-thiophene-carbaldehyde, 2-pyrrolecarbaldehyde, 4-pyridinecarbaldehyde and pyridoxal hydrochloride gave 6-chloro-2-[2-(2-furylmethylene)-1-methylhydrazino]quinoxaline 4-oxide 5a, 6-chloro-2-[1-methyl-2-(3-methyl-2-thienyl-methylene)hydrazino)quinoxaline 4-oxide 5b, 6-chloro-2-[1-methyl-2-(2-pyrrolylmethylene)hydrazino]quinoxa-line 4-oxide 5c, 6-chloro-241-methyl-2-(4-pyridylmethylene)hydrazino]quinoxaline 4-oxide 5d and 6-chloro-2-[2-(3-hydroxy-5-hydroxymethyl-2-methyl-4-pyridylmethylene)-l-methylhydrazino]quinoxaline 4-oxide 5e, respectively. The reaction of compound 5a or 5b with 2-chloroacrylonitrile afforded 8-chloro-342-furyl)4-hydroxy-1-methyl-2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxaline-5-carbonitrile 6a or 8-chloro-4-hydroxy-1-methyl-3-(3-methyl-2-thienyl)-2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxaline-5-carbonitrile 6b, respectively, while the reaction of compound 5e with 2-chloroacrylonitrile furnished 11-chloro-7,13-dihydro-4-hydroxy-methyl-5,14-methano-1,7-dimethyl-16-oxopyrido[3',4':9,811,5,6]oxadiazonino[3,4-b]quinoxaline 7.