2-Vinylpyrroles and Pyrrolo[3,2-d]pyrimidines from Direct Addition of Aldehydes to 4-Amino-pyrrole-2-carboxylate Derivatives

Abstract

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 pyrrolo[3,2-d]pyrimidines 1a-d in 28-63% yields.

β,β-Disubstituted C- and N-Vinylindoles from One-Step Condensations of Aldehydes and Indole Derivatives

“…The effective synthesis of 2vinylpyrroles was recently achieved by reacting 4aminopyrrole2carboxylates in condensations with aldehydes catalyzed by TFA . Considering their applications in medicinal chemistry and materials science, and limitations for their procurement, C and N vinylindoles were targeted using condensations of commercially available indoles and aldehydes in this onestep approach.…”

Diastereoselective Pictet−Spengler Approach for the Synthesis of Pyrrolo[3,2-e][1,4]diazepin-2-one Peptide Turn Mimics

“…The Pictet−Spengler reaction refers commonly to the condensation of a tryptamine analog with an aldehyde or ketone to yield a β-carboline; however, this intramolecular annulation via an imminium ion intermediate has been accomplished with a variety of amines tethered to electron-rich aromatic and heteroaromatic ring systems. Few reports have, however, described Pictet−Spengler reactions with pyrrole as the nucleophile. – For example, pyrrolo[3,2- e ]pyrimidines were made from the Pictet−Spengler reactions of ureidopyrroles and arylaldehydes …”