Organocatalytic Asymmetric Hydrophosphonylation/Mannich Reactions Using Thiourea, Cinchona and Bronsted Acid Catalysts

This account summarizes the results of recent studies conducted in our group on the development of chiral thiourea/cinchona and Bronsted acid derived bifunctional organocatalysts. Selected asymmetric organocatalytic transformations were targeted to obtain enantioenriched bioactive products. Special emphasis was placed on the preparation of environmentally friendly anti-plant viral agents such as enantiomerically enriched alpha-aminophosphonates and methods to assess the enantiomeric purity of these products on selected chiral stationary phases. The review also tries to delineate the underlying mechanism of various asymmetric transformations by BINOL-phosphoric acid-induced activation of imines and to make unambiguous assignments of the absolute configuration of alpha-aminophosphonates obtained from organocatalytic hydrophosphonylation of pregenerated and in situ generated imines.