Alkynylphosphines

The alkynylphosphine (56) reacts with Wilkinson s catalyst to give an intermediate rhodium complex, which, when treated with diphenylacetylene followed by cyanide ion, yields the diphosphine (57), of interest as a rigid chelating ligand of fixed geometry.47... 

Lanthanide metals catalyze intramolecular hydrophosphination-cyclization of alkenyl- and alkynylphosphines rapidly at room temperature [19]. As summarized in Table 3, the reaction is quite general. 

A nucleophilic addition to the triple bond in alkynylphosphine derivatives was observed by Laguna and Bardaji and although there was no evidence for a gold catalyzed cycle, reaction conditions were extremely milder than in the classic Reppe vinylation [94] (Scheme 8.12). 

A similar mechanism is apparently involved in the stereospecifie [tram) addition of hydrogen chloride to l-alkynylphosphines (7 of... 

Table 2). The kinetic data and, in particular, the effect of substituents (both R and R ) on the rate of addition indicate that the rate-determining step involves attack of the chloride ion to the triple bond of a protonated 1 -alkynylphosphine molecule (equation 8).

Ortho-lithiation of an O-protected m-fluorophenol, followed by treatment with phosphorus tribromide and aqueous acid deprotection, has given the phosphino-phenol 18. In the presence of potassium t-butoxide in an aprotic solvent, this is converted into the non-planar system 19, which exhibits pyroelectric properties. An organolithium route to the alkynylphosphine 20 has been developed. The same paper also reports a new route to the lithiated alkynylphosphine 21 and a study of its reactivity towards electrophiles. Diastereoselective lithiation of... 

The rates of acid-catalysed cyclization of certain alkynylphosphines to the cyclic diphosphonium salts (141) have been studied, and a mechanism has been proposed... 

Alkynylphosphines have also been shown to undergo an interesting double insertion with Ni(0)-benzyne complexes. Thus, two equivalents of Ph2P-CC-R insert into the Ni-benzyne bond in (24) to form a series of novel naphthalene-based bis(phosphine) ligands coordinated to the Ni center (25,... 

The diazo transfer from diazoalkanes to alkynes has also been applied to diphenyl-alkynylphosphine oxides. Low regiospecificity with unsymmetrically substituted alkynes was also observed here (Heydt and Regitz, 1977, 1978). 

Recent advances in the Staudinger reaction of tertiary phosphines with azido compounds have been reviewed.The reaction of the alkynylphosphine (88) with phenylazide yields the unstable intermediate (89), which in the presence of protic substances undergoes nucleophilic addition to the triple bond. The reactivity of the nitrogen-silicon bond of the phosphinimine derived from triphenylphosphine and trimethylsilylazide has been exploited in reactions with chloroformyl reagents to generate new functionalised phosphinimines, e.g., (90). ... 

The ligands PBujR (R = Me, Et, Pr) also yield trans-rhodium(TI) complexes when allowed to react with ethanolic solutions of RhClj 31120. If the reaction is carried out above 25°C o-metalla-tion does not occur, instead [RhHCl2(PBu2R)2] complexes are formed. The closely related alkynylphosphine ligand PBu2(C=CPh) also forms a hydridorhodium(TlI) complex when allowed to react with hydrated rhodium trichloride. Upon dissolution in chloroform, however, the red rhodium(III) hydrido complex decomposes and forms the orange binuclear rhodium(Il) complex... 

Nucleophilic attack of a metal-phosphido complex on an alk3me was also proposed in copper-catalyzed ann -hydrophosphination of 1-alkynylphosphines... 

Scheme 31 Proposed mechanism for copper-catalyzed anti-hydrophosphination of 1-alkynylphosphines with diphenylphosphine...

Hydrothiolation of 1-alkynylphosphines was catalyzed by P(OAc)2 in EtOH and gave Z-l-phosphino-2-thio-l-alkene as product (Scheme 3.87) [156]. Surprisingly, the addition reaction took place in the anti-fashion, which probably means an external nucleophilic attack on the coordinated triple bond as a key-step instead of the alkyne insertion observed in the other examples. 

Alkynylphosphines 352 undergo regio- and stereoselective carbometallation on treatment with magnesium dialkylcuprates leading to syn addition products (Scheme 10.120) [103]. 

Scheme 2.103 Pd-catalyzed annulation of 1-alkynylphosphine sulfides with 2-iodoanilines.

The C-P bond forming reaction between 1-alkynes and tetraphenylbiphosphine could be catalyzed by a Rh-complex in the presence of 2,4-dimethylnitrobenzene to afford alkynylphosphine oxides after a subsequent oxidation by hydrogen peroxide (Scheme 32). ... 

P-Silylvinylphosphine oxides were prepared regioselectively by the silylcupration of 1-alkynylphosphine oxides followed by hydrolysis (Scheme 36). The organosilyl-copper(i) reagents were prepared in situ from CuCN and 2 equivalents of organo-silyllithium. ... 

---