Synthesis of Pyrroles with Fused Carbocycles or Heterocycles from Weinreb N -Vinyl-α-amino Amides

Abstract

Pyrroles fused to diverse carbocycles and heterocycles were prepared from Weinreb N-vinyl-α-amino carboxamides integrated in cyclic systems. The selective reaction of the carboxamide group with organometallic compounds allowed us to obtain a great variety of the carbonyl intermediates analogous to the Knorr synthesis, which were thermally cyclized. The principal limitation of the method was due to the insolubility of some metallic intermediates as well as to the low nucleophilicity and stability of the enamine during the cyclization process.

Key words

Knorr pyrrole synthesis - Weinreb amides - fused pyrroles

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11

In the preparation of 53 we did not optimize the procedure or search for alternative methods for the low yield of their later transformation to indoles.