Isomerization phosphonites

These published data prompted the authors [82] to undertake a more detailed study of the phosphorylation of isatin by the esters of P(III) acids and hydrophosphoryl compounds. At room temperature in the absence of traces of moisture isatin 49a, 1-acetylisatin 49b, and 5-bromoisatin 49c react with trialkyl phosphites and phosphonites with the formation of the unstable 1,3,2-dioxaphospholanes 87 with a pentacoordinated phosphorus atom, which isomerize in alcohol solution to the stable phosphoryl compounds 88 ... 

Recently van Leeuwen reported the fiigt crystal structure of the diphosphite dicarbonyl rhodium catalyst HRh(CO)2(P P) [258]. Bomer et al. developed a new class of phosphonites which show promising results for the isomerization and subsequent hydroformylation of internal olefins [259]. The number of phosphite ligands based on supramolecular backbones such as calix[4]arenes is growing [260]. They are attractive because of their well defined structure combined with the ability to adopt several discrete conformations. Calix[4]arene diphosphites and calix[6]arene phosphites were first developed by BASF [261]. In... 

The nucleophilicity of the trivalent phosphorus and thus the reactivity increases with increasing +/ effect of substituents on the phosphorus atom. The phosphonous esters and, more so, phosphinous esters undergo the Arbuzov reaction more readily than do phosphorous esters.253 Methyl diphenylphos-phinite, for instance, reacts exothermally with methyl iodide even at room temperature, giving the isomeric phosphine oxide 254 although it is usual to work without a solvent, it is advisable to moderate the often very exothermic reaction of phosphonites by dilution with the reaction product and by carefully controlled portionwise addition of phosphonite. 

Rh4(CO)i2 in the hydroformylation of 2,3-dihydrofuran produced mainly tetrahydrofuran-2-carbaldehyde (Scheme 4.24) [18]. Also, modification of the metal by monodentate phosphites or phosphoramidites and bidentate phosphites favors a-regioselective hydroformylation as well as higher temperatures, low syngas pressure, and low P/Rh ratios [17, 19, 20]. PPhj or mixed bidentate phosphine phosphites and phosphine phosphonites stimulate isomerization and hence the formation of the fi-isomeric aldehyde [19, 21, 22]. There was no clear... 

Figure 5.6 Phosphites and phosphonites suitable for isomerization-hydroformylation.

Ni-Catalyzed Isomerization and Hydrocyanation with TTP-Type Phosphonite Ligands... 

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