An efficient asymmetric hydrophosphonylation of unsaturated amides catalyzed by rare-earth metal amides [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 with phenoxy-functionalized chiral prolinols

An asymmetric hydrophosphonylation reaction of diethyl phosphite with alpha, beta-unsaturated amides catalyzed by [(Me3Si) 2N](3)RE(mu-Cl) Li(THF)(3) (RE = Sc (1), Y (2), La (3), Yb (4) and Lu (5)) with H2Ln ((S)-2,4-R-2-6-[[2-(hydroxydiphenylmethyl) pyrrolidin-1-yl] methyl] phenol) (R = Bu-t (H2L1); R = 1-cumyl (H2L2) and R = 1-adm (H2L3)) was disclosed. The effects of different central metals and proligands on the addition reaction were tested and it was found that the combination of Sc complex 1 and ligand H2L2 gave the best results. An excellent chemical yield (up to 99%) and good to high enantioselectivities (varied from 73 to 89%) were achieved with a relatively broad scope of the unsaturated amides. The active species in the current system was also discussed.