Phosphine, methyl tris -, complex

PBF4O2WC2sH20> Tungsten, dicarbonyl(if -cyclopentadienyl) [tetrafluoroborato-(1 -)] (triphenylphosphine)-, 26 98 PBrF4N3RuCi4H2i, Ruthenium(II), tris-(acetonitrile)bromo(ft -1, S-cyclooctadiene)-, hexafluoro-phosphate(l —), 26 72 PC3H9, Phosphine, methyl-, iron complex, 28 177... 

Dimethyl 2-methylenepentanedioate. Methyl acrylate (30.0 g, 349 mmol) (distilled immediately before use) and dry pyridine (30 ml, CAUTION) containing tris(cyclohexyl)phosphine-carbon disulphide complex (2.0 g, 6 mmol) (1) are refluxed under nitrogen for 16 hours. The deep red solution is cooled and the pyridine removed under reduced pressure. The residue is taken up in ether (400 ml) and the solution washed with aqueous 1 m hydrochloric acid (3 x 40 ml). The combined aqueous layers are extracted with ether (2 x 50 ml) and the combined organic layers washed with 1 m hydrochloric acid (30 ml), saturated brine (40 ml) and saturated aqueous sodium hydrogen carbonate (2 x 30 ml), dried over sodium sulphate and evaporated. Distillation of the oil gives dimethyl 2-methylenepentanedioate (23.8 g, 79%) as a liquid, b.p. 66-68 °C/1 mmHg i.r. (thin film) 1738, 1715, 1635cm-1. 

THIOACETALS Methyl iodide. Silver oxide. Tricthyloxonium tetrafluoroborate. CONJUGATE ADDITION Cuprous bromide. Dimethylcopperlithium. Tri-n-butyl-phosphine-copperfl) iodide complex. CONVERSION OF - Br TO - OIID Silver sulfate. 

C,H,N, Benzene, 2-isocyano-l,3-dimethyl-, iron complexes, 26 53 57 C,H jN, Benzenemethanamine, N,N-di-methyl-, lithium complex, 26 152 Iutetium complex, 27 153 palladium complex, 26 212 QHijP, Phosphine, cthylmethylphenyl-, lithium complex, 27 178 C,H,3P, Phosphorane, dimethylmethylene-diphenyl-, uranium complex, 27 177 C,H P, Phosphine, triisopropyl-, rhodium complex, 27 292 tungsten complex, 27 7 C,Hj7PSi3, Phosphine, tris(trimethylsilyl)-, 27 243... 

CaH,2P, Phosphine, dimethylphenyl-ruthenium complex 26 273 C H,4, Cyclooctene platinum complex, 26 139 C,H,N, Benzene, 2-isocyano-l,3-dimethyl-iron complexes, 26 53, 57 CgHijN, Benzenemethanamine, iV,Ai,2-tri-methyl-... 

Complexes 79 show several types of chemical reactions (87CCR229). Nucleophilic addition may proceed at the C2 and S atoms. In excess potassium cyanide, 79 (R = R = R" = R = H) forms mainly the allyl sulfide complex 82 (R = H, Nu = CN) (84JA2901). The reaction of sodium methylate, phenyl-, and 2-thienyllithium with 79 (R = R = r" = R = H) follows the same route. The fragment consisting of three coplanar carbon atoms is described as the allyl system over which the Tr-electron density is delocalized. The sulfur atom may participate in delocalization to some extent. Complex 82 (R = H, Nu = CN) may be proto-nated by hydrochloric acid to yield the product where the 2-cyanothiophene has been converted into 2,3-dihydro-2-cyanothiophene. The initial thiophene complex 79 (R = R = r" = R = H) reacts reversibly with tri-n-butylphosphine followed by the formation of 82 [R = H, Nu = P(n-Bu)3]. Less basic phosphines, such as methyldiphenylphosphine, add with much greater difficulty. The reaction of 79 (r2 = r3 = r4 = r5 = h) with the hydride anion [BH4, HFe(CO)4, HW(CO)J] followed by the formation of 82 (R = Nu, H) has also been studied in detail. When the hydride anion originates from HFe(CO)4, the process is complicated by the formation of side products 83 and 84. The 2-methylthiophene complex 79... 

The beneficial effect of added phosphine on the chemo- and stereoselectivity of the Sn2 substitution of propargyl oxiranes is demonstrated in the reaction of substrate 27 with lithium dimethylcyanocuprate in diethyl ether (Scheme 2.9). In the absence of the phosphine ligand, reduction of the substrate prevailed and attempts to shift the product ratio in favor of 29 by addition of methyl iodide (which should alkylate the presumable intermediate 24 [8k]) had almost no effect. In contrast, the desired substitution product 29 was formed with good chemo- and anti-stereoselectivity when tri-n-butylphosphine was present in the reaction mixture [25, 31]. Interestingly, this effect is strongly solvent dependent, since a complex product mixture was formed when THF was used instead of diethyl ether. With sulfur-containing copper sources such as copper bromide-dimethyl sulfide complex or copper 2-thiophenecarboxylate, however, addition of the phosphine caused the opposite effect, i.e. exclusive formation of the reduced allene 28. Hence the course and outcome of the SN2 substitution show a rather complex dependence on the reaction partners and conditions, which needs to be further elucidated. 

The methyl iridium dioxygen complex Ir(CH3)C0(02)[P(p-tolyl)3]2 reacts with added triphenylphosphine to produce triphenylphos-phine oxide (191). That this is a bimolecular reaction was demonstrated both by the complete absence of any oxidation of the tris(para-tolyl)-phosphine and by the lack of any substitution of the bound tris(para-tolyl)phosphine by triphenylphosphine. 

Aqueous biphasic catalysis is also used in homogeneous hydrogenations.117-119 In new examples Ru clusters with the widely used TPPTN [tris(3-sulfonatophenyl) phosphine] ligand120 and Rh complexes with novel carboxylated phosphines121 were applied in alkene hydrogenation, whereas Ru catalysts were used in the hydro-genation of aromatics. Aerobic oxidation of terminal alkenes to methyl ketones was carried out in a biphasic liquid-liquid system by stable, recyclable, water-soluble Pd(II) complexes with sulfonated bidentate diamine ligands.124... 

Several chemical techniques have also been developed, such as simple oxidation using hydrogen peroxide or lead tetraacetate.77 Both these protocols suffer from harsh reaction conditions and additional toxicity issues. A more functional group-tolerant method is the use of tris(hydroxy-methyl)phosphine to coordinate the ruthenium.78 This complex is water soluble and can be washed from the product by several simple water washes. The main drawback to this method is the large excess of phosphine needed (25 mole equiv./mole of Ru).46... 

---