The Gewald Synthesis of 2-Aminothiophenes using Activated Sulfur

Significance

Reported is the use of an activated form of sulfur in the classical Gewald synthesis of substituted 2-aminothiophenes from ylidene­malononitriles which are easily obtained from ­malononitrile and the corresponding ketones. ­Activation of elemental sulfur was carried out by means of electrogenerated cyanomethyl anion, obtained by galvanostatic reduction from MeCN/Et₄NPF₆ system. The substrate scope was poorly studied as only two examples were reported involving a different ylidene (R^¹ = CONH₂ or CO₂Et).