Synthesis and some reactions of quinoxalinecarboazides

Article abstract of DOI:10.1002/jccs.200000046

Chlorination of ethyl(quinoxalin-2(1 H)one)-3-carboxylate 1 gave ethyl (2-chloroquinoxaline)-3-carboxylate 2;thionation of 1 by P₂S₅ or 2 by thiourea yielded the same product 3.Reaction of chloro compound 2 or thiocompound 3 with hydrazine hydrate gave pyrazolylquinoxaline 4. The reaction of ester 1 with thiourea or hydrazine hydrate afforded pyrimidoquinoxaline 5 or carbohydrazide 6; the reaction of 6 with carbon disulfide in basic medium followed by alkylation afforded oxadiazoloquinoxaline derivatives 7, 8a, b. Carboazide 9 was produced by reaction of 5 with nitrous acid. Compound 9 on heating in an inert solvent, with or without amines, in alcohols or hydrolysis in H₂O undergoes Curtius rearrangments to yield 10-13.Reaction of 13 with thiosemicarbazide gave triazoloquinoxaline 14 which on reaction with alkylhalides or hydrazine hydrate yielded 15a-c while hydrolysis of 13 gave 3-aminoquinoxalinone 16 which was used as an intermediate to produce 17-20.