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Modification of (1R,2S)-1,2-Diphenyl-2-aminoethanol for the Highly Enantioselective, Asymmetric Alkylation of N-Diphenylphosphinoyl Arylimines with Dialkylzinc

✍ Scribed by Hai-Le Zhang; Fan Jiang; Xiao-Mei Zhang; Xin Cui; Liu-Zhu Gong; Ai-Qiao Mi; Yao-Zhong Jiang; Yun-Dong Wu

Publisher
John Wiley and Sons
Year
2004
Tongue
English
Weight
284 KB
Volume
10
Category
Article
ISSN
0947-6539

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✦ Synopsis

Abstract

Experimental studies on the modification of (1__R__,2__S__)‐1,2‐diphenyl‐2‐aminoethanol, which is used to promote the alkylation of N‐diphenylphosphinoyl benzalimine with diethylzinc, revealed that N‐monosubstituted amino alcohols exhibited higher enantioselectivities than their N,N‐disubstituted counterparts and imino alcohols. Application of the optimal chiral ligand 3 c to activate the reaction of N‐diphenylphosphinoyl arylimines with diethylzinc and dibutylzinc resulted in excellent enantiomeric selectivities of up to 98 % ee. The origin of the experimentally observed enantioselectivities was revealed by density functional calculations (B3LYP/6‐31G*) on the transition structures of several model reactions.

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