Synthesis of New Pyrrolo Heterocycles (I): Novel Synthesis of Pyrano [2, 3‐c] pyrrole, Isoindoline, Pyrrolo [3, 4‐b] pyridine, and Pyrrolo [3, 4‐d] pyrimidine Derivatives

Michael addition of 1,5-diaryl-2,3-dioxopyrrolidine derivatives with α-cyanocinnamonitriles and ethyl α-cyanocinnamates afforded 4H-pyrano[2,3-c]pyrrole derivatives in the presence of sodium ethoxide. Under the same reaction condition, the ylidenes of 1,5-diaryl-2,3-dioxopyrrolidine were reacted with malononitrile or ethyl cyanoacetate to give isoindole derivatives; however, pyrrolo[3,4-b]pyridine derivatives were formed when cyanoacetamide was used. Moreover, pyrrolo[3,4-d]pyrimidine derivatives were synthesized by treating 4-benzylidene-1,5-diphenyl-2,3-dioxopyrrolidine with urea and/or thiourea under basic conditions. The structures of all the new synthesized compounds were confirmed by elemental analysis, IR and NMR spectra.