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.
Knorr pyrrole synthesis - Weinreb amides - fused pyrroles
