Chemistry: A European Journal 2010-01-18

Synthesis and application of modular phosphine-phosphoramidite ligands in asymmetric hydroformylation: structure-selectivity relationship.

Xiaowei Zhang, Bonan Cao, Yongjun Yan, Shichao Yu, Baoming Ji, Xumu Zhang

Index: Chemistry 16(3) , 871-7, (2010)

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Abstract

A series of hybrid phosphine-phosphoramidite ligands has been designed and synthesized in moderate yields from chiral BINOL (1,1'-bi-2-naphthol) or NOBIN (2-amino-2'-hydroxy-1,1'-binaphthyl). They have achieved highly regio- and enantioselectivities in Rh-catalyzed asymmetric hydroformylations of styrene derivatives (branched/linear ratio up to 56.6, ee up to 99 %), vinyl acetate derivatives (up to 98 % ee), and allyl cyanide (up to 96 % ee). Systematic variation of ligand structure showed that the steric factor on the phsophoramidite moiety determined the performance of the ligand. With the increased hindrance, the branched/linear ratio rose, while the ee value dropped in the hydroformylation of styrene. However, the N-substituents did not influence the selectivities much.