REGIOSELECTIVE SYNTHESES OF 1-,2-,3-AND 4-AMINOINDOLO-2,3-bQUINOXALINES

摘要

In view of the contradictory results published in the literature concerning the structure of the indoloquinoxalines obtained by condensation of isatin with an unsymmetrical benzene-1,2-diamine,regioselective syntheses of the 1-,2-,3-,and 4-aminoindolo2,3-bquinoxalines have been developed.With the four derivatives in hand,isomers obtained by direct cyclocondensations starting from amino or nitro substituted benzene-1,2-diamines could be unambiguously identified.The results of these studies show,on the one hand,that some previous findings need revision and,on the other hand,that the 1-amino isomer could be prepared in one step and in 58 yield.