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SiocPhox ligands

Allylic alkylations have also been used to create optically pure all-carbon quaternary stereocentres, which is a daunting task in organic synthesis. Although some encouraging results have been obtained with SiocPhox ligands with acyclic nucleophiles, most of the work involves cyclic nucleophiles. For instance, a few examples of alkylations of (3-keto esters leading to quaternary centres are depicted in Scheme 8.10. [Pg.461]

This reaction proceeds by nucleophilic attack of the stabilised carbanion of 70 to the central carbon of the 7i-allylic complex derived from carbonates 71. It was found that for these substrates SiocPhox ligands favour cyclopropanation over the most common allylic alkylation. After removal of the allylic substitution products and oxidative treatment, " cyclopropanes 72 were generally obtained in good yields and excellent diastereo- and enantio-selectivities. [Pg.481]

Scheme 8.28 Pd-catalysed cyclopropanations with a SiocPhox ligand. Scheme 8.28 Pd-catalysed cyclopropanations with a SiocPhox ligand.
An interesting family of P,N ligands, known as SiocPhox, was prepared by Hou, Dai and co-workers (Scheme 2.53). ... [Pg.85]

With these substrates, achiral 1-24 is strongly favoured with Pd catalysts (for other metals, the situation is different) except in special cases. Diazaphos-pholidine-oxazoline 20 shows moderate performance in the alkylation of butenyl acetate compared to the exceptionally good results with SiocPhox phosphonamidate ligands for alkyl- and aryl-substituted substrates. The same type of ligands have also been applied to the alkylation of other challenging substrates such as polyenyl esters and acyclic ketone enolates. ... [Pg.460]


See other pages where SiocPhox ligands is mentioned: [Pg.85]    [Pg.85]   
See also in sourсe #XX -- [ Pg.85 , Pg.460 , Pg.481 ]




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