Tri-tert-butylphosphine: Phosphine, tris

Tri-tert-butylphosphine Phosphine, tri-tert-butyl- (8) Phosphine, tris(1,1 -dimethylethyl)- (9) (13716-12-6)... 

One of the most important transformations catalysed by palladium is the Heck reaction. Oxidative addition of palladium(O) into an unsaturated halide (or tri-flate), followed by reaction with an alkene, leads to overall substitution of a vinylic (or allylic) hydrogen atom with the unsaturated group. For example, formation of cinnamic acid derivatives from aromatic halides and acrylic acid or acrylate esters is possible (1.209). Unsaturated iodides react faster than the corresponding bromides and do not require a phosphine ligand. With an aryl bromide, the ligand tri-o-tolylphosphine is effective (1.210). The addition of a metal halide or tetra-alkylammonium halide can promote the Heck reaction. Acceleration of the coupling can also be achieved in the presence of silver(I) or thallium(I) salts, or by using electron-rich phosphines such as tri-tert-butylphosphine. ... 

Purification by vacuum distillation (102—103 °C, 13 Torr). Handling, Storage, and Precautions the pure material is pyrophoric and must be handled under an oxygen-free atmosphere to avoid spontaneous combustion. In the absence of oxygen, it is indefinitely stable. Solutions (ca. 10%) of tri-tert-butylphosphine are not pyrophoric, but should be handled under an inert atmosphere in order to avoid oxidation to the phosphine oxide. The HBF4 salt is air-stable. Tri-tert-butylphosphine is corrosive and causes burns on contact with skin. It is incompatible with oxidizing agents. 

A mixture of cinnamyl alcohol, phenyl isocyanate, heptanal, tri-n-butylphosphine, and a little Pd(PPh3)4 in acetonitrile refluxed for 5 h - product. Y 82% (E,E E,Z 4 1). The phosphine attacks the less hindered carbon of the intermediate n-allyl complex, and the (E)-geometry of the allyl alcohol is retained for tert. allylic alcohols, reaction requires prior formation of the allyl carbamate ketones react sluggishly. Although stereoselectivity is poor, the method is interesting since intermediate phosphonium salts are formed under neutral conditions. F.e. and polyenes s. N. Okukado et al., Chem. Letters 1988, 1449-52. 

A similar protocol for the arylation of isoquinohne A-oxides has been described. A screen of different phosphines showed that di-tert-butyl(methyl)phosphonium tetrafluorohorate provides a greater regioselectivity in favor of the Cl-arylated compound than tricyclohexyl or tri-terf-butylphosphine (eq 2). 

Other classes of heterocycles that have been arylated using the C-H activation method and involving palladium acetate and tri-tert-butylphosphonium tetrafluorohorate include the quinoline N-oxides (eq 25) and the thiazoleiV-oxides (eq 26). In the case of quinoline (V-oxides, the regioselectivity of arylation is as expected and leads to the corresponding 2-aryl derivatives. However, in the case of thiazole IV-oxides, the nature of the phosphine has a dramatic influence on the regioselectivity of the arylation process, with tri-terf-butylphosphine providing the product of C5 arylation. 

Phosphorus(V) from phosphorus(lll) compounds. Tribulylphosphine added at 25° under Ng during 30 min. with water-cooling to N,N-diethyl-2,2,2-trichloro-acetamide, and kept an additional 4 hrs. at 50-55° N,N-diethyl-l,2,2-trichloro-vinylamine (startg. m. f. 442) (Y 82.5%) and tri-n-butylphosphine oxide (Y 72.6%).—This new reaction appears to be general for tert. phosphines and trialkyl phosphites. It also represents a novel method for the prepn. of a new class of vinylamines. F. e., also with trialkyl phosphites, which are oxidized to trialkyl phosphates, s. A. J. Speziale and R. G. Freeman, Am. Soc. 82, 903 (1960). 

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