ChapterI contains a review of phosphoniteisn asymmetric catalysis and recent developments in asymmetric hydrogenation and a symmetric hydroformylation catalysis. Chapter2 is concerned with new phosphonite ligands f r asymmetric catalysis. A new three-steps ynthesiso f 9,9'-biphenanthryl-10,10'-dio(lb iphenanthrol') in 36% yield from phenanthrene is reported. The ligands PhP(OR)2, PhP(OR')2, (RO)2PCH2CH2P(OR)2a nd Ph2PCH2CH2P(OR)2 derived from 'biphenanthrol' (HOR)2 and dimethyl-1,1'-binaphthyl-2,2'-dihydroxy-3,3'-dicarboxylate( HOR')2 have been synthesised and their Pt(O,I I) and R h(I) chemistry is discussed The crystal structures of two complexes of the type [PtC12(phosphonite)h2a] ve been determined. The monoPhosphonite, diphosphonite and phosphinophosphonite complexes [Rh(cod)P2]BF4 derived from (S)-'biphenanthroal'r e described. In Chapter 3, the chemistry of some new diphosphites is described. The diastereomeric mixture of (RO)2P(ORRO)P(OR)2( 'biphenanthrite') is formed by reacting (±)-'biphenanthrol' with PC13- Optically pure (R, R, R)-'biphenanthrite' is similarly prepared from (R)-biphenanthrol'.The side-products and intermediates in this reaction are identified by their independent syntheses C: IP(OR)2,H (O)P(OR)2, (RO)2POP(OR)a2n d (HORRO)P(OR)2 Dehydration of 'biphenanthrola' lso occurs to give a furan, which was characterisedb y X-ray crystallography. Two equivalents of (R)-CIP(OR)2 react with (R)- or (S)-'binaphthol' (HOR")2 to give (R, R, R)- and (R, S, R)-(RO)2P(OR"R"O)P(OR)2 ('pnp'). The disodium salt of (±)-'biphenanthrol' reacts with two equivalents of (±)-CIP(OR)2 to yield the single ((R, SR) / (SR, S))- diastereomeor f 'biphenanthriteT. he Pt(II), Pd(11aI)n dR h(I) coordinationc hemistry of these new diphosphitesis reported. The complexes[ MC12(diphosphite)a] re fluxional due to the conformational flexibility of the nine-memberech delate ring and the crystal structures of (R,R ,R )- and (SR,S )-[PtC12('biphenanthrite)s]h ow very different ring conformations T.he hydroformylation of styrenes catalysed by rhodium(I) complexes of (R, R, R)-'biphenanthrite', (R, S, R)-'pnp' and (R, R, R)-pnp' is reported. The 'biphenanthritec' complex gives 50% branched aldehyde and no asymmetric induction. The complex of (R, SR)-'pnp' gives 91-96% branched aldehyde and up to 72% ee. The differences in the catalytic properties of the diastereomer is discussed. In Chapter4 , the asymmetric hydrogenation of oc-enamides with rhodium(I) complexes of the new phosphonites and diphosphitesa s catalysts is discussed The diphosphonite complex shows low activity and a modest ee (up to 41%) but the analogousp hosphinophosphonitceo mplex is highly active and gives high ee's (up to 88%).T his is the first phosphinophosphonittoe be used in asymmetric hydrogenation. The monophosphonitceo mplexi s very activea ndt he ee's of up to 92% aret he highest obtained with a monodentatleig and in asymmetric cc-enamide hydrogenation. Chapter5 gives the experimental details for the chemistry reported in this thesis.

Achiral wide bite angle ligands have been shown to be highly active and to induce excellent chemo- and regioselectivities in many homogeneously catalyzed reactions. However, only a few examples of chiral wide bite angle ligands are known so far. A diphenyl ether backbone was selected to allow maximum synthetic versatility and potential for a modular approach to design and synthesize such chiral diphosphorus ligands. Three synthetic strategies have been explored in this thesis: i) introduction of chiral substituents in the ligand backbone, ii) the use of P-stereogenic donor atoms and iii) the synthesis of chiral mixed-donor ligands bearing chiral auxiliary groups on the phosphorus atoms. Functionalization of the 3,3'-positions of 2,2'-bis(diphenylphosphino)diphenyl ether by carboxylic acid or ether auxiliaries was achieved via straightforward four-step routes to generate a library of ligands that were tested in various catalytic reactions. In the Pd-catalyzed asymmetric allylic alkylation of l,3-diphenyl-2-propenyl acetate and cyclohexyl-2-enyl acetate with dimethyl malonate the enantioselectivity was found to depend on the size of the chiral auxiliary introduced within the diphenyl ether backbone and its proximity to the phosphorus donor groups and hence to the active metal centre. Two types of mixed donor bidentate diphosphorus ligands based on the diphenylether backbone have been established, i.e. phosphine-phosphite and phosphine-phosphonite derivatives. A small ligand library bearing different chiral auxiliaries was accomplished via straightforward syntheses that enable derivatization of the respective phosphite and phosphonite moieties in the final step. In the Rh-catalysed hydrogenation of several benchmark substrates high conversion and moderate to high enantioselectivities (up to 97% for dimethyl itaconate) were obtained. The enantioselectivity was influenced by the size of the ortho-substituent on the chiral auxiliary group of the phosphite or phosphonite fragment. Two modular synthetic approaches for the preparation of novel wide bite angle diphosphine ligands containing stereogenic P-atoms have been developed. Both protocols involved diphenylether as backbone and the chiral ephedrine based precursor (2R[subscript(P)],4S[subscript(C)],5R[subscript(C)])-oxazaphospholidine borane as initial auxiliary to induce chirality at phosphorus. Various novel diphosphines were isolated as highly enantioenriched compounds with dr-ratios up to 95:5.