Rh−DuPHOS-Catalyzed Enantioselective Hydrogenation of Enol Esters. Application to the Synthesis of Highly Enantioenriched α-Hydroxy Esters and 1,2-Diols
作者:Mark J. Burk、Christopher S. Kalberg、Antonio Pizzano
DOI:10.1021/ja974278b
日期:1998.5.1
The asymmetric hydrogenation of α-(acetyloxy)- and α-(benzoyloxy)acrylates 4 catalyzed by cationic rhodium−DuPHOS complexes has been examined. A wide range of substrates (4) were prepared via a convenient Horner−Emmons condensation protocol, and subsequently hydrogenated under mild conditions (60 psi of H2) at substrate-to-catalyst ratios (S/C) of 500. Overall, enol ester substrates 4 were reduced