Phosphorus—hydrogen bonds reactions with

Transformations of phosphines to difluorophosphoranes proceed with xenon difluoride under mild conditions and in high yields, and the phosphorus-hydrogen bond is stable chlorine atoms are replaced by fluorine in chlorine-phosphorus molecules, while triphenyl and trimethyldifluorophosphorane are isolated in 90-100% yield130-132. Reactions of compounds containing P—N, P—O and P—S bonds with xenon difluoride proceed by fragmentation or dimerization133 (Scheme 55). 

These results indicate that acetyl phosphinate is the most potent active site-directed inactivator of PFL now known. Although it is not yet clear what the overall mechanism of inactivation might be, consistent with the mechanism for the normal PFL reaction proposed by Kozarich and co-workers (Scheme 41) (187), there is the intriguing possibility that phosphorus-carbon or phosphorus-hydrogen bond cleavage might occur. These possibilities are currently being... 

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. ... 

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