CATALYTIC ASYMMETRIC AMINOHYDROXYLATION OF OLEFINS WITH CARBAMATES

摘要

beta -Hydroxyamines and beta -hydroxycarbamates are synthesized from olefin substrates by means of a catalyzed asymmetric addition reaction. The addition reaction is catalyzed by osmium and is co-catalyzed by chiral ligands. The chiral ligands, in addition to being co-catalysts with the osmium, also serve to direct the addition reaction regioselectively and enantioselectively. Divalent ligands are preferred over monovalent ligands because of their enhanced regio- and enantio-selectivity. Carbamates are employed as an oxidant nitrogen source for the production of beta -hydroxysulfonamides. Excellent yields and enantiomeric efficiencies are achieved with co-solvents containing 50/50 (v/v) mixtures of water and organic solvent. The performance of the reaction is further enhanced by omitting the addition silver or mercurial salts conventionally employed in asymmetric aminohydroxylation additions to olefins performed in neat or substantially neat solvents. beta -Hydroxyamines are then obtained by deprotecting the corresponding beta -hydroxycarbamate.