Synthesis of heterofunctionalized multidentate diphosphines

The synthesis of new chiral multidentate amino- and amidophosphine ligands bearing up to six potential coordination sites were synthesized starting fr om L-valine. Based on these compounds chiral Ru(II) complexes were prepared , characterized and tested in the asymmetric transfer hydrogenation of aryl -alkyl ketones. In all cases investigated the catalyst bearing additional h ydroxy groups gave lower conversions than the complex without hydroxy group s. Highest enantioselectivity was achieved with isobutyrophenone as substra te (69%ee). (C) 2000 Elsevier Science Ltd. All rights reserved.