Catalytic enantioselective carbon-carbon bond forming reactions of masked acyl cyanides

Protected hydroxyl malononitriles, known as masked acyl cyanide (MAC) reagents are one of the most useful umpolung synthons to function as carbon monoxide equivalents with both nucleophilic and electorophilic reactivity. This dual reactivity, only characteristic in a few acyl anion equivalents, enables MAC reagents to afford a series of structurally diverse products by a one-carbon homologation under mild conditions. This review highlights the utility of MAC reagents in catalytic enantioselective carbon-carbon bond forming reactions that have been reported recently.