Selective ortho lithiation of (2,5-dimethoxyphenyl)diphenylphosphine oxide and trapping of the resulting aryllithium with electrophiles
摘要:
The title compound undergoes predominant 6-lithiation, ortho to the methoxy and phosphinoyl groups, on reaction with t-BuLi in THF under conditions of thermodynamic control at low temperature. The organolithium compound is stable at least to 0-degree-C and can be trapped by a range of electrophiles to give the corresponding tetrasubstituted (diphenylphosphinoyl)arenes in moderate to good yield. The iodide formed by this sequence undergoes Ullman coupling to the diphenyl, which exhibits a novel restricted rotation phenomenon, in good yield under mild conditions. (2,5-Dimethoxyphenyl)diphenylphosphine sulfide lithiates exclusively at the 4-position under the same conditions, whilst the corresponding phosphine is unreactive.
Horner, L.; Simons, G., Phosphorus and Sulfur and the Related Elements, 1983, vol. 14, p. 189 - 210
作者:Horner, L.、Simons, G.
DOI:——
日期:——
Palladium(<scp>II</scp>) 2-diphenylphosphinohydroquinone (H<sub>2</sub>pphq) complexes: preparation and structures of a novel cluster, [{PdBr(Hpphq)}<sub>4</sub>]·2H<sub>2</sub>O, and a phosphine–phosphinite complex, cis-[PdBr<sub>2</sub>{C<sub>6</sub>H<sub>3</sub>(OH)-1,PPh<sub>2</sub>-3,PPh<sub>2</sub>O-4}]·2H<sub>2</sub>O
作者:Seri Bima Sembiring、Stephen B. Colbran、Donald. C. Craig、Marcia L. Scudder
DOI:10.1039/dt9950003731
日期:——
The complexes [PdCl2(PPh(3))L(2)] (L(2) = 1,4-dimethoxy-2-diphenylphosphinobenzene) [PdCl(bipy)L(2)](+) (bipy = 2,2'-bipyridine) and [PdCl2(mpy)L(2)] (mpy = 4-methylpyridine) have been prepared and their reactions with BBr3 studied. The first two complexes afforded products resulting from protolytic cleavage of the phosphinohydroquinone ligand whereas reactions of the last with BBr3 produced [PdBr(mpy)(Hpphq-O,P)] (H(2)pphq = H(2)L(1) = 2-diphenylphosphinohydroquinone) when quenched with methanolic sodium carbonate or, when quenched with methanol alone, a mixture which contains the novel tetrameric cluster [PdBr(HL(1))}(4)] and slowly deposits an unexpected phosphine-phosphinite complex, cis-[PdBr2C6H3(OH)-1,PPh(2)-3,PPh(2)O-4}]. H2O, on standing. The crystal structures of the last two complexes have been determined. The palladium tetramer was also formed when [PdBr(mpy)(HL(1)-O,P)] was treated with hydrobromic acid. The NMR spectra suggest that in solution the tetramer is in equilibrium with monomeric solvato complexes, [PdBr(solv)(HL(1)-O,P)] (solv = solvent).
HORNER, L.;SIMONS, G., PHOSPH. AND SULFUR, 1983, 14, N 2, 189-209