Furanoside diphosphines derived from D-(+)-xylose and D-(+)-glucose as ligands in rhodium-catalysed asymmetric hydroformylation reactions

摘要

Chirality transfer by furanoside diphosphines 1-3 was investigated in the Rh-catalysed asymmetric hydroformylation of prochiral olefins. In general, they induced high regioselectivities with branched aldehydes and moderate enantioselectivities of up to 58%. Improved activities were seen when a methyl substituent was introduced at C-(5) of the sugar residue. Systematic variation of the configuration at C-(5) suggests that there is a cooperative effect between stereocentres, which results in a matched combination for ligand 3 with (R)-configuration at the C-(5) stereogenic centre. Introduction of a methyl substituent at C-(5) induces a strong coordination preference. The solution structures of the species formed under hydroformylation conditions were also investigated. (C) 2001 Elsevier Science Ltd. All rights reserved. [References: 36]