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New C 2 ‐Symmetric Diphosphite Ligands Derived from Carbohydrates: Effect of the Remote Stereocenters on Asymmetric Catalysis
Author(s) -
Axet M. Rosa,
BenetBuchholz Jordi,
Claver Carmen,
Castillón Sergio
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200600654
Subject(s) - hydroformylation , chemistry , stereocenter , rhodium , tetrahydrofuran , catalysis , nuclear magnetic resonance spectroscopy , stereochemistry , asymmetric hydrogenation , medicinal chemistry , organic chemistry , enantioselective synthesis , solvent
The synthesis of new modular chiral diphosphite ligands with C 2 ‐symmetry and carbohydrate backbone is reported. We also report here the synthesis of the corresponding rhodium complexes [Rh(COD)(L)]BF 4 (L=diphosphite). All these species have been characterised in solution by NMR spectroscopy and in some cases in the solid state by X‐ray diffraction. The solution structures of the hydridorhodiumcarbonyl species [RhH(CO) 2 (L)], where L=diphosphites 12a – 14a , 12b , have been studied using high‐pressure NMR spectroscopy. The configuration and substitution of the remote stereocentres in positions 2 and 5 of the tetrahydrofuran ring of the diphosphite ligands were observed to have a considerable influence on the results obtained in the rhodium‐catalysed hydroformylation and hydrogenation reactions. Thus, the configuration of the major isomer obtained in the hydroformylation reaction may be controlled by changing the configuration of these stereocentres.