DESIGN OF METHOXY-SUBSTITUTED BPPM ANALOGUES AND THEIR APPLICATION TO THE ASYMMETRIC SYNTHESIS OF N__-ACETYLPHENYLALANINE

抄録

We describe the preparation of methoxy-substituted BPPM ((2S__-, 4S__-)-N__--((tert)___--butoxycarbonyl)-4-(diphenylphosphino)-2-[(diphenylphosphino)-methyl]pyrrolidine) analogues for highly effective asymmetric hydrogenation of (Z__-)-2-acetamidocinnamic acid. o__--Methoxy-BPPM-Rh⁺ gave a very high optical yield (98% enantiomeric excess (ee), (R__-)) and p__-methoxy-BPPM-Rh⁺ was very actively catalytic ([Subst.]/[Rh]=10⁴). On the bases of these results and our "respective control concept, " we developed a highly effective chiral ligand (5) for asymmetric synthesis of N__-acetylphenylalanine.