Synthesis of Highly Substituted Pyridines via a One-Pot, Three-Component Cascade Reaction of Malononitrile with Aldehydes and S-Alkylisothiouronium Salts in Water

A novel methodology for the synthesis of 2-amino-4-aryl(alkyl)-6-sulfanyl pyridine-3,5-dicarbonitriles via a one-pot, three-component reaction of structurally diversified aldehydes with various S-alkylisothiouronium salts and malononitrile in water has been developed. Utilization of S-alkylisothiouronium salts as thiol equivalents greatly broadens the application of the current method, and also makes the reaction more environmentally friendly.