Development and application of chiral spirocyclic phosphoric acids in asymmetric catalysis.

The development of suitable chiral catalysts, which represent powerful, economically feasible tools for the preparation of optically active organic molecules, is a fundamental endeavour in synthetic chemistry. Chiral phosphoric acids derived from axially chiral 1,1'-bi-2-naphthol (BINOL) are a widely used class of strong Brønsted acid catalysts and have been applied successfully in many asymmetric catalyzed reactions. Accordingly, the development and application of chiral spirocyclic phosphoric acids derived from axially chiral 1,1'-spirobiindane-7,7'-diol (SPINOL) have received increasing attention in the last eight years. This review covers the synthetic methods and the application of chiral spirocyclic phosphoric acids in asymmetric catalysis.