Asymmetric C-C bond formation with L-prolinol derived chiral catalysts immobilized on polymer fibers

N-(4-Vinylbenzyl)-alpha,alpha-diphenyl-L-prolinol was immobilized on polyethylene fibers by electron beam induced pre-irradiation grafting using styrene as a co-monomer. The resulting polymer supported catalyst P2 was utilized in asymmetric C-C bond forming reactions and its performance compared with those of previously prepared fibrous cross-linked alpha,alpha-diphenyl-L-prolinol P1 and homogeneous model compounds. The fibrous catalyst yields similar enantioselectivities in the asymmetric addition of diethylzinc to benzaldehyde as its homogeneous reference reaction and can be recycled with minimal loss of activity. When P2 was used as the catalyst in the addition of phenylacetylene to benzaldehyde, the corresponding propargylic alcohol was obtained with enantiomeric excesses of up to 91%. (C) 2003 Published by Elsevier Ltd.