The application and development of cyanating reagents in asymmetric cyanation reactions

Chiral nitriles are not only widely found in pharmaceutical and agricultural compounds, but also serve as important intermediates in organic synthesis. Traditional methods to synthesize nitriles involve the use of simple cyanating reagents such as sodium cyanide, potassium cyanide, hydrogen cyanide and the equivalents. However, the toxicity and volatility of these cyanating reagents limit their application in synthesis. Therefore, there is a growing interest to develop organic cyano-transfer reagents and cyanide-free precursors to produce chiral cyano-containing compounds and nitriles. This review systematically analysed the recent development and application of organic cyanating reagents to the catalytic asymmetric cyanation reactions, highlighting these impressive advances to illustrate their main advantages and future applications.