Evaluation of Chiral Oxazolines for the Highly Enantioselective Diethylzinc Addition to N-(Diphenylphosphinoyl) Imines

Autor: Xin Cui, Aiqiao Mi, Yaozhong Jiang, Kai-Bei Yu, Hai-Le Zhang, Xiaomei Zhang, Liu-Zhu Gong, Wenqing Lin
Rok vydání: 2003
Předmět:
Zdroj: ChemInform. 34
ISSN: 1522-2667
0931-7597
DOI: 10.1002/chin.200339027
Popis: On the basis of the principle that the incorporation of the structurally rigid and conformationally restricted skeleton in beta-amino alcohols is beneficial to the enantioselective diethylzinc addition to imines, a series of chiral oxazolines, which had been designed and conveniently prepared from commercially available (1S,2S)-2-amino-1-phenylpropane-1,3-diol, were applied in the diethylzinc addition to diphenylphosphinoyl imines to give high yields of 68-84% and excellent ee values of 90-95%. The configuration of the product was controlled by the chirality of the carbon bonded to the hydroxyl group in the oxazoline. Oxazolines bearing a para- or meta-substituted phenyl group generally offered higher enantioselectivity than those containing an ortho-substituted phenyl. The X-ray structures of 4f and 4j, in combination with the proposed transition state, preliminarily explained why oxazolines with a para- or meta-substituent on the phenyl group gave higher enantioselectivities than those bearing an ortho-substituent. This successful example using chiral oxazolines to promote the titled reaction implies that a large family of chiral compounds containing an oxazoline ring moiety have the potential to be developed for promoting the highly enantioselective dialkylzinc addition to N-(diphenylphosphinoyl) imines.
Databáze: OpenAIRE
Externí odkaz: