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Application of Supramolecular Bidentate Hybrid Ligands in Asymmetric Hydroformylation
Author(s) -
Bellini Rosalba,
Reek Joost N. H.
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201202044
Subject(s) - hydroformylation , chemistry , denticity , supramolecular chemistry , steric effects , ligand (biochemistry) , phosphoramidite , stereochemistry , pyridine , catalysis , combinatorial chemistry , styrene , rhodium , metal , organic chemistry , molecule , copolymer , dna , biochemistry , polymer , receptor , oligonucleotide
Abstract In this study we report a novel class of supramolecular bidentate hybrid ligands in which the two inequivalent phosphorus units and pyridine moieties are covalently attached to a chiral scaffold and the supramolecular interactions are used as a second handle to control the coordination sphere around the transition‐metal centre. The coordination chemistry of these ligands was investigated under hydroformylation conditions by high‐pressure NMR and IR spectroscopy, revealing the formation of a single active species in which the phosphane ligand is in the axial position and the phosphoramidite adopts the equatorial position. These ligands were applied in the asymmetric Rh‐catalysed hydroformylation of styrene and para ‐substituted analogues. In these hydroformylation reactions, modification of the electronic and steric properties of the zinc(II)‐templates appear to have a significant influence on the activity and selectivity of the catalysis. In particular, zinc(II)‐templates bearing more electron‐withdrawing substituents led to an increase in enantioselectivity.