Diphenylphosphine-4-benzoic acid

Kaneda et al. [33,34] have recently utilized acid-base interactions to non-covalently attach diphenylphosphine-4-benzoic acid palladium complexes to the exterior of poly(propyleneimine) dendrimers and to cavities within these dendrimers (Fig. 9) via the interaction of the benzoic acid with the carboxyl groups of amide moieties positioned within the dendrimer. Interestingly, the supramolecular dendritic catalyst gave rise to much more active catalysts for... 

Reactions with alkynes may lead to the formation of cyclized products. The reaction of iodobenzenes with two equivalents of an alkyne has been shown to give naphthalene derivatives in the presence of cobalt catalyst with a manganese reduc-tant. The process, shown in Scheme 15, is thought to involve oxidative addition of the aryliodide to cobalt followed by double alkyne insertion. The cobalt-catalysed annulation step probably involves an pathway. The cyclopentadienyl-rhodium-catalysed annulation of benzoic acids with alkynes has been used to form isocoumarin derivatives, such as (126). The process is thought to involve cyclorhodation at the ortho-position of a rhodium benzoate intermediate, followed by alkyne insertion to form a seven-membered rhodacycle and reductive elimination The silver-catalysed annulations of diphenylphosphine oxides with alkynes proceed in the absence of rhodium. Benzophosphole oxides such as (127), formed with diphenylethyne, are produced. Here, the proposed mechanism involves homolytic cleavage of the phosphorus-hydrogen bond to give a radical which can add to the alkyne and subsequently cyclize. ... 

In an effort to develop new systems able to combine both stability and activity, Siiss-Fink and co-workers reported a family of trans-spanning, but flexible diphosphines.These ligands form stable complexes, due to the chelate effect, which resemble the ones obtained with PEts, (/r . r-[RhI(CO)(PEt3)2]), with the two phosphorus atoms in a /r< //i -disposition. These ligands, as benzoic acid diphenylphosphine derivatives, are supposed to increase the electron density on the rhodium center due to a weak Rh-O interaction. 

Cordova [72] in 2007. Both groups reported a hydrophosphination of enals with diphenylphosphine (88) catalyzed by diarylprolinol derivatives 27 (Scheme 33.22). The reactions were performed in the presence of benzoic acid derivatives as co-catalyst, and the originally formed adducts were either reduced to alcohols, which are stable and easier to handle, or oxidized to obtain the phosphine oxide derivatives. In both cases the reaction afforded the phosphine derivatives in good yields and enantioselectivities. 

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