Journal of Molecular Catalysis A-Chemical, Vol.258, No.1-2, 216-220, 2006
Asymmetric addition of diethylzinc to benzaldehyde catalyzed by silica-immobilized titanium(IV) complexes of N-sulfonylated amino alcohols
A chiral (1R,2S)-2-(p-toluenesulfonylamino)-1,3-diphenyl-1-propanol derived catalyst was synthesized and successfully grafted onto amorphous silica gel and mesoporous silica (MCM-41) by a facile approach. This is the first use of silica-immobilized titanium(IV) complexes of N-sulfonylated amino alcohols for the asymmetric addition of diethylzinc to benzaldehyde with good enantioselectivity (80% e.e.). Particularly, after readily recoverble procedure, the catalyst was able to be reused in multiple catalytic runs (up to 10 times) without loss of enantioselectivity. (c) 2006 Elsevier B.V. All rights reserved.
Keywords:asymmetric addition;silica-immobilized catalyst;titanium tetraisopropoxide;N-sulfonylated amino alcohol;diethylzinc