A vanety of cationic palladium complexes beanng crural bidentate ligands and weakly coordinating counter-anions were synthesised and characterised Their reactivity under conditions relevant to carbonylation catalysis was studied When the diaquo complex [{(5)-MeO-BIPHEP|Pd(H20)2](OTf)2 was dissolved in methanol, the formation of the dimeric palladium(I) complex [( (5) -MeO-BIPHEPlPd] 2(OTf) 2 was observed In contrast, under CO pressure, the (i-hydndo-H-carbonyl-bndged binuclear palladium(I)

more »

... ex [)(5)-MeO-BIPHEP|Pd(|X-HXu-CO)Pdl( 5)-MeO-BIPHEP}]OTf was formed The palladium-catalysed enantioselective bis-alkoxycarbonylation reaction of a-olefins, leading to optically active substituted butanedioates, was realised For styrene as the olefinic substrate, screening experiments were carried out using atropisomenc diphosphines as the chiral modifier Reaction conditions were established under which high enantioselectivites (up to 93% ee) and good chemoselectivites for the synthesis of dimethyl 2-phenyl-butanedioate were reached For aliphatic a-olefins, such as propene, 3-phenyl 1-propene and 4methyl-1-pentene, the enantioselectivites and chemoselectivites were lower The lower optical punties in the case of the aliphatic a-olefins probably denved from a regioirregular olefin insertion into a palladium carbomethoxy bond A new enantioselective carbonylation reaction of a-olefins was developed, i e the 'tnple carbonlyation' of a-olefins leading to optically active substituted 2 oxopentanedioates The reaction is completely regioselective for styrene, whereas with aliphatic a-olefins two regioisomers are formed Even if the chemoselecuvity is not high, this reaction allows a one step synthesis of the substituted 2-oxopentanedioates with fair to excellent enantioselectivity (up to 92% ee for the formation of dimethyl 2-oxo-3 phenyl-pentanedioate) Taking into account the structural data of some catalyst precursors, gained by X-ray structure determinations, a model for the transition states, in which asymmetnc induction occurs, was developed For almost all the catalytic systems applied, the (relative) absolute configurations of the regioisomenc substituted 2-oxo-pentanedioates were predicted Based on the regioisomenc ratio as well as the enantiomenc ratios of the 2-oxo-pentanedioates, the enantiomeric excess and the absolute configuration respectively of the contemporaneously formed dimethyl 2-phenyl-Summary xx