Phosphites and Phosphoramidites

Chiral monodentate phosphites and phosphoramidites are also effective ligands for Rh-catalyzed asymmetric hydrogenation of enamide substrates. As seen in the structure of MonoPhos illustrated in Figure 1.2, combination of the mod-ihed BINOF backbone and the amine part gives a structural variety to this type of ligand. Combinatorial methods are effective for optimization of the chiral structures.Elucidation of the hydrogenation mechanism catalyzed by the MonoPhos-Rh complex is in progress." ... 

The Lewis acid-catalysed 3 + 2-cycloaddition of cyclopropanes with aldehydes yields tetrahydrofurans with high diastereoselectivity.22 The enantiospecific Sn(II)-and Sn(IV)-catalysed formal 3 + 2-cycloadditions of aldehydes with donor-acceptor (g) cyclopropanes produce optically active tetrahydrofurans23 The bulky phosphites and phosphoramidites are excellent ligands which promote the Pd-catalysed 3 + 2-intramolecular cycloaddition between alkylidenecyclopropanes and alkynes24 The... 

Asymmetric Olefin Hydrogenation Using Monodentate BINOL- and Bisphenol-Based Ligands Phosphonites, Phosphites, and Phosphoramidites... 

Kondo, H, Ichikawa, Y, Wong, C-H, (i-Sialyl phosphite and phosphoramidite synthesis and application to the chemoenzymatic synthesis of CMP-sialic acid and sialyl oligosaccharides, J. Am. Chem. Soc., 114, 8748-8750, 1992. 

Several reports of the additions of phosphites and phosphoramidites to carbonyl groups have appeared. In the case of aminophosphines, these involve the well-documented rearrangement to the a-amino-compound (23), and for the vinyl ketone (24) the product is (25), reaction at the carbonyl group competing favourably with Michael addition (Scheme 5). The already extensively studied, but still some-... 

Scheme 3.26 P-stereogenic binaphthol-derived phosphites and phosphoramidites.

Reetz and co-workerspublished the only examples of binaphthol-based P-stereogenic phosphites and phosphoramidites. They were prepared from known ort/ro-monosubstituted binaphthols (92) via classical phosphitylation methods (Scheme 3.26). 

A selection of monodentate phosphite and phosphoramidite ligands used for asymmetric hydrogenation. 

Rh-catalyzed Arylation of Heterocycles. Arylation of benzimidazole was achieved using aryl iodides in the presence of a Rh catalyst and 40 mol % of PCys. Other ligands, such as alkyl and aryl phosphines, phosphites, and phosphoramidites, produced inferior conversions compared with tricyclohexylphosphine. Excess phosphine inhibited the reaction, suggesting that phosphine dissociation occurs prior to oxidative addition of the aryl iodide. 

Bruneau C, Renaud J-L. Monophosphinites, -aminophos-phinites, -phosphonites, phosphites and -phosphoramidites. In Bomer A, editor. Phosphorus ligands in asymmetric catalysis. Synthesis and applications. Weinheim Wiley-VCH 2008. p 36-69. 

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