Novel, cyclic and bicyclic 1,3-diols as catalysts for the diethylzinc addition to aldehydes

Abstract

A number of optically pure 1,3-diols have been synthesized and used as catalysts in the asymmetric addition of diethylzinc to aromatic aldehydes. Enantiomeric excesses of up to 92% of (R)-1-phenylpropan-1-ol were obtained with anisylbicyclo[2.2.2]octanediol (14) as a catalyst. Using 2-picolylbicyclo[2.2.2]ocatanediol (16) as the catalyst resulted in a reversal of the stereoselectivity, yielding (S)-1-phenylpropan-1-ol in 83% ee. A pronounced positive non-linear effect was observed when varying the enantiomeric purity of catalyst 14.