([2]Paracyclo[2](5,8)quinolinophan-2-yl)carbinols as catalysts for diethylzinc addition to aldehydes: cooperative effects of planar and central chirality on the asymmetric induction

A systematic study to assess the contribution of planar and central chirality to the asymmetric induction in the diethylzinc addition to aromatic and aliphatic aldehydes has been carried out using planar chiral quinolinophanylcarbinols (R-p)-1 and (R-p)-11 and diastereomeric quinolinophanylcarbinols (R-p,R)- and (R-p,S)-5-8, exhibiting both planar and central chirality Lis catalysts. The stereochemistry of the addition process leading to aryl- or 1-alkylpropanols seems to be mostly controlled by the central chirality. Nevertheless, the planar chirality shows a remarkable cooperative effect oil the degree of asymmetric induction, which turns Out to be positive or negative depending oil the configuration of the stereogenic carbon of the catalyst. (C) 2005 Elsevier Ltd. All rights reserved.