Enantioselective reactions of N-acyliminium ions using chiral organocatalysts.

N-acyliminium ions are reactive intermediates that can act as electron-deficient electrophiles toward weak or soft nucleophiles, thereby providing useful methods for both intermolecular- and intramolecular carbon-carbon and carbon-heteroatom bond formation. Nucleophilic additions to N-acyliminium ions constitute an important method for providing α-functionalized amino compounds and many other biologically active nitrogen-containing heterocycles. The development of efficient catalytic asymmetric reactions is a key objective in modern organic chemistry and is very important for the synthesis of natural products, pharmaceuticals, and agrochemicals. Various methods are available for this purpose and mostly rely on the use of chiral catalysts for enantioselective synthesis. This review deals with one aspect of such catalysis, which has emerged only in the past few years, and its applications in enantioselective reactions of N-acyliminium ions to provide various nitrogen-containing heterocycles.