Rational design of chiral catalysis for the enantioselective addition reaction of dialkylzincs

Design of chiral catalysts for the enantioselective addition of dialkylzinc s to aldehydes and enones is described. Important factors in the design of highly enantioselective catalytic reaction is the structure of substituent of catalyst, the structure of heterocyclic moiety and the solvent. Diphenyl (1-methlylpyrrolidin-2-yl)methanol (DPMPM) and N,N-dialkylnorephedrines are highly enantio- and chemoselective chiral catalysts for the addition of di alkylzincs to various aldehydes, affording sec-alcohols with high enantiome ric excesses. Pyrimidyl, pyridyl and quinolyl alkanols are highly enantiose lective asymmetric autocatalysts in the enantioselective isopropylation of the corresponding pyrimidine-, pyridine- and quinoline-carbaldehydes. Pract ically perfect asymmetric autocatalysis (>99%, >99.5% ee) has been achieved with 2-alkynylpyrimidyl alkanol. Asymmetric autocatalyst with low ee (0.2- 2%) multiplied with amplification of enantiomeric excess (ca. 90% ee). Usin g N,N-dialkylnorephedrines in mixed solvent containing acetonitrile, conjug ate addition of dialkylzinc to enones affords beta-substituted ketones in h igh ee.