CATALYZED ASYMMETRIC REACTION OF ALDEHYDES WITH DIALKYLZINC IN THE PRESENCE OF CHIRAL PYRIDYL ALCOHOLS AS LIGANDS

The synthesis of homochiral pyridyl alcohols (1,2,3a-c) and a catalyti c asymmetric addition of dialkylzinc to various aldehydes using 1-3 as ligands are described. Although the reaction of benzaldehyde with Et2 Zn in the presence of (S)-1 and (R,R)-2 gave (S)- and (R)-1-phenyl-1-p ropanol, respectively, in moderate enantiomeric excess (e.e.), trident ate ligands (3a-c) accelerated the reaction to produce the correspondi ng alcohols in high e.e. Particularly, (S)-3b was found to be the most efficient catalyst, for which asymmetric reactions of various aldehyd es with dialkylzinc gave the corresponding alcohols in good to high e. es. (up to 95% e.e.).