Synthesis of pyrrolo[1,2-a]indole-1,8(5H)-diones as new synthons for developing novel tricyclic compounds of pharmaceutical interest

In the course of our work aimed at developing novel heterocycles of pharmaceutical interest, a new tricycle, the tetrahydropyrrolo[1,2-a]indole-1,8-dione, has been synthesized by an intramolecular Friedel-Crafts acylation, as a synthon suitable to be functionalized to give novel compounds with potential biological properties. Also, an unusual nucleophilic α-addition to methyl propiolate by 1,5,6,7-tetrahydro-4H-indol-4-one was observed and discussed.