([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

Abstract

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 as 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 on the degree of asymmetric induction, which turns out to be positive or negative depending on the configuration of the stereogenic carbon of the catalyst.