2-vinylpyrroles and pyrrolo[3,2-d]pyrimidines from direct addition of aldehydes to 4-amino-pyrrole-2-carboxylate derivatives

A new methodology for the direct preparation of 2-vinylpyrroles is presented. Treatment of 4-amino-pyrrole-2-carboxylates 5a-c and 6a-d with aliphatic aldehydes and TFA furnished 2-vinylpyrroles 2a-k in 9-87% yields. Under similar conditions ureidopyrroles 5a-c reacted with aryl aldehydes to provide pyrrolo3,2-d]pyrimidines 1a-d in 28-63% yields.