Asymmetric catalysis .104. Double stereoselection in rhodium catalysts in enantioselective hydration of (Z)-alpha-N-acetylaminocinnamic acid

Optically active rhodium catalysts with double stereoselection were prepared from the optically active chelating phosphanes Diop and Norphos and eta-1,5-cyclooctadiene rhodium complexes which contain the anions of optically active 1,3-diketones and 1,3-ketoimines based on camphor. Use of these complexes in the homogeneous enantioselective hydrogenation of (Z)-alpha-N-acetamidocinnamic acid to N-acetylphenylalanine gave optical inductions up to 90.7% and 92.3% ee for Diop and Norphos complexes, respectively. These results exceed those obtained with the corresponding phosphane-rhodium systems without additional optically active coligands.