Phosphine-containing

This can be extracted from impure phosphine prepared by the action of sodium hydroxide on phosphorus. Unlike hydrazine, it has no basic properties. It is a powerful reducing agent and burns spontaneously in air, this reaction explaining why impure phosphine containing traces of diphosphane ignites spontaneously in air. 

A different task was pursued by the CM of CsA with various maleates 339 [ 148]. The CM demanded in this case the highly active Hoveyda catalyst D, that exhibits potency not reached by the phosphine-containing catalysts C and E. Under the conditions given in Scheme 65, metathesis with maleates 339 led (E)-selectively to the a,/J-unsaturated ester derivatives 340 in high yield. Compounds 340 still demonstrated activity comparable to that of CsA and are thus potential soft drugs via esterase-mediated biotransformation to the corresponding inactive carboxylic acids 341. 

Scheme 1.55 Test reaction with thiophene- and benzothiophene-oxazoline/ phosphine-containing ligands.

Bleaching Activity of Phosphines Containing Hydroxymethyl Groups... 

Togni and co-workers have used the convergent methodology to link phosphine-containing chiral ferrocene ligands on the cyclophosphazene core to obtain dendrimeric structures of the type 37 (Fig. 21) (201). The reaction with the cyclophosphazene end occurs by the replacement of the P-Cl bond and by the formation of the P-0 bond. The dendrimers contain twelve and sixteen ferrocene moieties respectively. The phosphine units present can coordinate to Rh(I) to afford metallic dendrimers, which have been shown to be excellent catalysts for the enantioselective hydrogenation of dimethyl itaconate. The product... 

Figure 17.18 The Staudinger ligation reaction uses a modified phosphine derivative containing an electrophilic group that acts as a trap for the nucleophilic nitrogen in the intermediate aza-ylide. The resultant shift yields an amide bond derivative between the phosphine-containing molecule and the azide-containing molecule.

Figure 17.22 Certain unique phosphine derivatives can be used in the design of modification or conjugation reagents to create a traceless Staudinger ligation process, wherein the phosphine group is lost and an amide bond between an azide-containing molecule and the phosphine-containing molecule results.

Gilbertson, S.R. and Starkey, G.W., Palladium-catalyzed synthesis of phosphine-containing amino acids,. Org. Chem., 61, 2922, 1996. 

Gilbertson, S.R., Chen, G., and McLoughlin, M., Versatile building block for the synthesis of phosphine-containing peptides. The sulfide of diphenylphos-phinoserine, ]. Am. Chem. Soc., 116, 4481, 1994. 

Gilbertson used the diversity available from the use of the 20 natural amino acids in peptides by creating two new phosphine-containing amino acids 9 a and b these were incorporated in the form of their thiooxides 8 into random peptide sequences (Fig. 36.4) [29]. 

Scheme 36.9 Libraries of phosphine-containing helical undecapeptides.

Another elegant example of phosphine-containing dendrimers is represented by dendrimer 10 in Scheme 10 [17]. These structures are build up via nitrogen branching points while the final nitrogen branching point is used to make a... 

This type of reverse set-up has been expanded to catalysts with phosphines containing crown ether substituents (Figure 8.1), with the crown ether acting as a built-in phase-transfer function [5], Using a catalyst with this phosphine, the hydrogenation of Li+, Na+, K+ and Cs+ cinnamates in water-benzene solvent mixtures was considerably faster than when the analogous catalyst was used with triphenylphosphine ligands. 

Phosphine-containing compounds are prepared by reaction of [PPh3(CO) Mn]2 with silanes and this reaction allows the synthesis of an optically active complex ... 

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