Construction of chiral Ti(IV)-Rh(I)-salenophos complexes and their application in the asymmetric hydroformylation of functionalised olefins

The synthesis of new chiral salenophos-type ligands bearing 'hard' and 'sof t' coordination sites is described. The polyfunctionalised ligands are used for the construction of monometallic and early-late heterobimetallic compl exes. In the reaction with titanium(IV) reagents the salen subunit selectiv ely coordinated to the 'hard' metal. The phosphine groups in turn can be co ordinated to rhodium(I). The coordination geometry of the diphosphine-Rh su bunit is strongly influenced by the counter ligands COD or CO and Cl, respe ctively. In the asymmetric hydroformylation of vinyl acetate with one of th e Rh-Ti-complexes, the branched aldehyde is predominantly formed with 30% e e. (C) 1999 Elsevier Science Ltd. All rights reserved.