Simple Synthesis of (I*-Ethene)bis(triphenylphosphane)platinum(O)The title compound 2 is easily accessible through reduction of dichlorobis(tripheny1phosphane)-platinum(I1) (1) with sodium tetrahydridoborate in ethanol under ethene pressure or without pressure in methylene chloride/ethanol. No nitrogen atmosphere or purified solvents are necessary.

Eine einfache Synthese von (R.R)-3,4-Bis(diphenylphosphino)pyrrolidin (6a)und Rhodium Complexes for the Asymmetric Hydrogenation of a-(Acy1arnino)acrylic Acid DerivativesA simple synthesis of (R,R)-3,4-bis(diphenylphosphino)pyrrolidine (6a) and some N-substituted derivatives 6b-m is described. 61 and 6m are optically active tetraphosphanes, composed of two (R,R)-3,4-bis(diphenylphosphino)pyrrolidine units and a dicarboxylic residue. The structure of the parent compound 6a was determined by X-ray diffraction. From the phosphanes 6a -m the cationic 1,5-cyclooctadiene-bisphosphane-rhodium complexes 7a-rn were prepared. The complexes 71 and 7m are ligand bridged bis(rhodium) dications. The complexes 7a-m were used for the asymmetric catalytic hydrogenation of the a-(acy1amino)acrylic acid derivatives 9a -I. Enantiomeric excesses up to 100% were achieved. Between 1 and 70 at the optical yields do not depend on the hydrogen pressure. The substrateJcatalyst ratio can be as high as 5ooOoJ1. *) Zusammenarbeit bei der Verkiirzung der urspriinglich langeren Synthese von 6b.

No abstract

No abstract

A novel, chiral bisphosphane ligand with variable N‐substituents is contained in the Rh complex 1. 1 (BF4 salt) catalyzes the hydrogenation of α‐(acetylamino)cinnamic acid, even at high H2‐pressure and with large amounts of substrate, in up to 99% ee. 1 is also highly propitious when bonded to carriers.