Highly active chiral phosphoramide-Zn(II) complexes as conjugate acid-base catalysts for enantioselective organozinc addition to ketones.
A highly efficient enantioselective organozinc (R2Zn) addition to ketones catalyzed by chiral phosphoramide-Zn(II) complexes (1-10 mol %) has been developed. These complexes serve as conjugate Lewis acid-Lewis base catalysts. Chiral phosphoramides are derived from an inexpensive natural amino acid (i.e., L-valine). From a variety of nonactivated aromatic and aliphatic ketones, the corresponding optically active tertiary alcohols were obtained in high yields with high enantioselectivities (up to 98% ee) under the mild reaction conditions.
Hatano
Manabu
M
Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8603, Japan.
Miyamoto
Takashi
T
Ishihara
Kazuaki
K