Asymmetric synthesis of chiral, nonracemic dialkyl-α-, β-, and γ-hydroxyalkylphosphonates via a catalyzed enantioselective catecholborane reduction
摘要:
A highly enantioselective synthesis of dialkyl alpha-hydroxyphosphonates achieved by a oxazaborolidine catalyzed reduction with catecholborane starting with m-ketophosphonates is described. Both alpha-aryl- and alpha-alkylketophosphonates were reduced using the (S)-enantiomer of the catalyst 4 leading also to the (S)-configuration in the products 2. The reaction gave good chemical yields and excellent enantiomeric excesses (up to >99 % ee).