The Gewald Reaction is a synthesis of 2-aminothiophenes via a multi-component condensation between sulfur, an α-methylene carbonyl compound and an α-cyanoester.
Mechanism of the Gewald Reaction
First step in the process is a Knoevenagel Condensation, but the remainder of the sequence is not known in detail:
An Efficient One-Pot Synthesis of Substituted 2-Aminothiophenes via Three-Component Gewald Reaction Catalyzed by L-Proline
T. Wang, X.-G. Huang, J. Liu, B. Li, J.-J. Wu, K.-X. Chen, W.-L. Zhu, X.-Y. Xu, B.-B. Zeng, Synlett, 2010, 1351-1354.