Rhodium-Catalyzed Enantioselective Michael Addition of (1-Cyanoethyl)phosphonate: Synthesis of Optically Active Phosphonic Acid Derivatives with Phosphorus-Substituted Quaternary Asymmetric Carbon Center

摘要

Asymmetric Michael addition of diethyl (1-cyanoethyl)phosphonate with vinyl ketones or acrylaldehyde in the presence of 0.01 molar amount of a rhodium catalyst prepared in situ from Rh(acac) (CO)_2 and a trans-chelating chiral diphosphine ligand (R,R)-(S,S)-2,2''-bis[1-(diphenylphosphino)ethyl]-1,1''-biferrocene (PhTRAP) in benzene at 3 ℃ gave optically active phosphonates having a phosphorus-substituted quaternary asymmetric carbon center with high enantiomeric excesses (92-93% ee) in high yields. The Michael addition product from acrylaldehyde was converted into an optically active (1-aminoalkyl) phosphonic acid derivative.