SYNTHETIC STUDIES ON INDOLES AND RELATED-COMPOUNDS .39. NEW STRATEGY FOR INDOLE SYNTHESIS FROM ETHYL PYRROLE-2-CARBOXYLATE

As a synthetic application of the previously reported C-4-acylation of ethyl pyrrole-2-carboxylate (1), a new strategy for indole synthesis was developed, Ethyl pyrrole-2-carboxylate (1) was allowed to react wi th succinic anhydride or 3-methoxycarbonylpropionyl chloride to give, in good yield, a C-4-succinyl derivative of 1, which was converted int o ethyl 7-oxo-4,5,6,7-tetrahydroindole-2-carboxylate (6) as a key inte rmediate for indole synthesis, Starting from 6, several indoles functi onalized on the benzene moiety were synthesized.