Cyanide Anions as Nucleophilic Catalysts in Organic Synthesis

The nucleophilic addition of a cyanide anion to a carbonyl group is the basis for several cyanide-catalyzed organic reactions, which are summarized in this review. Since cyanide is also a good leaving group, it is an excellent catalyst for transacylation reactions. As an electron-withdrawing group, it also stabilizes a negative charge in its alpha-position, thus allowing the umpolung of aldehydes to formyl anion equivalents. The two leading examples are the benzoin condensation and the Michael-Stetter reaction furnishing alpha-hydroxy ketones and 1,4-dicarbonyl compounds, which are both catalyzed by cyanides. The review also covers variants like the silyl-benzoin coupling, the aldimine coupling and the imino-Stetter reaction. Moreover, some cyanide-catalyzed heterocyclic syntheses are reviewed.

Automated summary

The nucleophilic addition of a cyanide anion to a carbonyl group serves as the basis for several cyanide-catalyzed organic reactions, with examples including the benzoin condensation and the Michael-Stetter reaction. Apart from the fundamental reactions, variants like the silyl-benzoin coupling and cyanide-catalyzed heterocyclic syntheses are also covered.