The acid-mediated intramolecular 1,3-dipolar cycloaddition of derived 2-nitro-1,1-ethenediamines for the synthesis of novel fused bicyclic isoxazoles

The discovery of a novel synthesis of new fused bicyclic isoxazoles, for example, N-methyl-3-phenyl-5,6-dihydro-4H-isoxazolo[3,4-c]azepin-8-amine (2a), N-methyl-3-phenyl-4,5-dihydroisoxazolo[3,4-c]pyridin-7-amine (2b) and N-methyl-3-phenyl-4H-pyrrolo[3,4-c]isoxazol-6-amine (2d) in high yield is reported. We speculate that the reaction proceeds via acid-mediated intramolecular 1,3-dipolar cycloaddition from 2-nitro-1,1-ethenediamines 1a,b,d.