α,β-Unsaturated aldehydes in the synthesis of pyrroles (microreview)

This review is devoted to the methods of pyrrole synthesis on the basis of alpha,beta-unsaturated aldehydes, which have been reported over the previous 10 years. Synthesis of these heterocyclic systems is most commonly achieved by multicomponent reactions. The participation of aliphatic, aromatic, and alpha-branched enals in such reactions has enabled the preparation of a whole series of target pyrroles featuring various combinations of substituents. It was shown that the reaction can involve both double bonds (CH= CH and CH= O) of the unsaturated aldehyde, while there are also examples where the aldehyde group remains intact.