Controlled oxidative addition of amino acid esters to Rh(I)

Abstract

The new sterically demanding phosphine 2-(di-o-tolylphosphino)phenol was prepared and used to create a series of esters with N-acylated amino acids. The phosphine-containing esters react within 30–60 min at room temperature with [(μ-Cl)Rh(cyclooctene)2]2 to give products of oxidative addition of the ester carbonyl–oxygen bond to the Rh center. The N-acyl carbonyl oxygen is bound to the Rh in these initial adducts, but is displaced upon addition of PMe3. Remarkably, both initial products and their PMe3 adducts are formed as single five-coordinate diastereomers in essentially quantitative yields.