New C2-Symmetric Diphosphite Ligands Derived from Carbohydrates: Effect of the Remote Stereocenters on Asymmetric Catalysis

✍ Scribed by M. Rosa Axet; Jordi Benet-Buchholz; Carmen Claver; Sergio Castillón

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 521 KB
• Volume: 349
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200600654

✦ Synopsis

Abstract

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.