Bis-phosphite ligands

Figure 2 Union Carbide bis-phosphite ligands for normaZ-selective hydroformylation.

Suresh D, Balakrishna MS, Rathinasamy K et al (2008) Large-bite bis(phosphite) ligand containing mesocyclic thioether moieties synthesis, reactivity, group 11 (Cu-I, Au-I) metal complexes and anticancer activity studies on a human cervical cancer (HeLa) cell line. Dalton Trans 2285-2292... 

The formation of cationic nickel hydride complexes by the oxidative addition of Brdnsted acids (HY) to zero-valent nickel phosphine or phosphite complexes (method C,) has already been discussed in Section II. Interesting in this connection is a recent H NMR study of the reaction of bis[tri(o-tolyl)phosphite]nickelethylene and trifluoroacetic acid which leads to the formation of a square-planar bis[tri(o-tolyl)phosphite] hydridonickel trifluoroacetate (30) (see below) having a cis arrangement of the phosphite ligands (82). 

It has been suggested that bis(equatorial) (ee) coordination of bidentate P-donor ligands in [HRh(CO)2(diphosphine)] (structure 5) can favor high linear/branched product ratios relative to systems which prefer equatorial-axial (ea) chelation (structure 6). For the bulky bis-phosphite 7 shown in Scheme 3.4, HP IR in conjunction... 

Industrial efforts have been focused on manufacturing of t>r/ 7/-aldehydes ( linear aldehydes) from olefins. Here, we briefly summarize its history on the development of phosphorus ligands, which are classified as monophosphine, monophosphite, bis-phosphite, and bis-phosphine, all useful for the normal-sc cct vc hydroformylation. 

A number of papers on asymmetric hydroformylation of olefins using chiral bis-phosphite or bis-phosphine ligand were reported by 2000. Here, we focus on some examples that achieved high enantioselectivities. 

One of the drawbacks of the use of bisphosphines is the elaborate syntheses necessary for their preparation. Many efforts have been directed towards the development of bis-phosphonites and bis-phosphites. However, surprisingly mono-dentate phosphinates, phosphates and phosphoramidates recently emerged as effective alternatives for bidentate phosphines (Fig. 3.29). This constitutes an important breakthrough in this area as these can be synthesized in one or two steps, and the cost of these ligands is an order of magnitude lower Monophos can be made in a single step from BINOL and HMPT. 

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