1445-83-6Relevant academic research and scientific papers
A Mild One-Pot Reduction of Phosphine(V) Oxides Affording Phosphines(III) and Their Metal Catalysts
Kapu?niak, ?ukasz,Plessow, Philipp N.,Trzybiński, Damian,Wo?niak, Krzysztof,Hofmann, Peter,Jolly, Phillip Iain
supporting information, p. 693 - 701 (2021/04/06)
The metal-free reduction of a range of phosphine(V) oxides employing oxalyl chloride as an activating agent and hexachlorodisilane as reducing reagent has been achieved under mild reaction conditions. The method was successfully applied to the reduction of industrial waste byproduct triphenylphosphine(V) oxide, closing the phosphorus cycle to cleanly regenerate triphenylphosphine(III). Mechanistic studies and quantum chemical calculations support the attack of the dissociated chloride anion of intermediated phosphonium salt at the silicon of the disilane as the rate-limiting step for deprotection. The exquisite purity of the resultant phosphine(III) ligands after the simple removal of volatiles under reduced pressure circumvents laborious purification prior to metalation and has permitted the facile formation of important transition metal catalysts.
Poly(methylhydrosiloxane) as a green reducing agent in organophosphorus-catalysed amide bond formation
Hamstra, Daan F. J.,Lenstra, Danny C.,Koenders, Tjeu J.,Rutjes, Floris P. J. T.,Mecinovi?, Jasmin
supporting information, p. 6426 - 6432 (2017/08/10)
Development of catalytic amide bond formation reactions has been the subject of the intensive investigations in the past decade. Herein we report an efficient organophosphorus-catalysed amidation reaction between unactivated carboxylic acids and amines. Poly(methylhydrosiloxane), a waste product of the silicon industry, is used as an inexpensive and green reducing agent for in situ reduction of phosphine oxide to phosphine. The reported method enables the synthesis of a wide range of secondary and tertiary amides in very good to excellent yields.
Organocatalyzed Reduction of Tertiary Phosphine Oxides
Schirmer, Marie-Luis,Jopp, Stefan,Holz, Jens,Spannenberg, Anke,Werner, Thomas
supporting information, p. 26 - 29 (2016/01/25)
A novel selective catalytic reduction method of tertiary phosphine oxides to the corresponding phosphines has been developed. Notably, the reaction proceeds smoothly with low catalyst loadings of 1-5 mol% even at low temperature (70 C). Under the optimized conditions various phosphine oxides could be selectively reduced and the desired phosphines were usually obtained in excellent yields above 90%. Furthermore, we have developed a one-pot reaction sequence for the preparation of valuable phosphinborane adducts. Simple addition of BH3THF subsequent to the reduction step gave the desired adducts in yields up to 99%.
Novel Base-Free Catalytic Wittig Reaction for the Synthesis of Highly Functionalized Alkenes
Schirmer, Marie-Luis,Adomeit, Sven,Spannenberg, Anke,Werner, Thomas
supporting information, p. 2458 - 2465 (2016/02/12)
A highly efficient catalyst system for base-free catalytic Wittig reactions has been developed and optimized. Initially, several potential (pre)catalysts as well as different silanes as reducing agents were screened. A system based on a readily available
Reactivity of Cyclopentenyl-Anion-Analogous Heterocycles: Homophospholes - Synthesis, 1,5-Electrocyclization, and Inversion at the Phosphorus Atom
Klaerner, Frank-Gerrit,Oebels, Dirk,Sheldrick, William S.
, p. 473 - 484 (2007/10/02)
The key step of a novel homophosphole synthesis is the reaction of phospholes 3a-d with diazomethane in the presence of water leading to the oxidized 1,3-dipolar cycloadducts anti-7a-d.The 1,5-electrocyclization of homophosphole was observed by the temperature-dependent rate of racemization of optically active anti-8b (ΔH(excit.) = (31.24 +/- 0.59) kcal/mol; ΔS(excit.) = -(2.32 +/- 1.47) cal/mol K).In order to determine the activation parameters for the inversion at the phosphorus atom a (60:40) mixture of syn- and anti-homophosphole syn- and anti-8b was prepared by H2O2 oxidation of anti-8b complexed by CuCl and subsequent reduction with Cl3SiH.The enantiomerization (-)-anti-8b> proceeds at 169.5 deg C 22 times faster than the inversion at the phosphorus atom (anti-8b -> syn-8b).This shows unambiguously that the electrocyclic ring opening does not require a planar configuration at the phosphorus atom and can start from the nonplanar anti configuration due to a dihedral angle of ca. 0 deg between the orbital of the lone pair at the phosphorus atom and the cyclopropane Walsh orbitals favourable for a strong electronic interaction in this configuration.From the comparison of the activation parameters for the inversion at the phosphorus atom in the homophosphole (syn-8b anti-8b) and the dihydrophosphole (+)-23> one can extrapolate, that the homoaromatic resonance stabilization in the planar homophosphole is small (ca. -2 kcal/mol) contrary to the surprisingly large aromatic stabilization in the planar phosphole (ca. -20 kcal/mol). Key Words: Homophospholes / Phospholes, 4,5-dihydro, optically active / 1,5-Electrocyclization / Phosphomethine ylides / Inversion at the phosphorus atom
THE PREPARATION OF OPTICALLY ACTIVE PHOSPHINES BY ASYMMETRIC REDUCTION OF RACEMIC PHOSPHINE OXIDES
MacPherson, Andrew J.,Smith, David J. H.
, p. 315 - 345 (2007/10/02)
The reduction of (R,S)-1-phenyl-3-methyl-2-phospholene 1-oxide (3) with lithium aluminium hydride has been studied to explain some of the anomalies reported for the reduction of (3) with optically active alanes.Reductions of acyclic racemic chiral phosphines oxides using optically active alanes and lithium aluminium hydride doped with (S)-2-(anilinomethyl)-pyrrolidine is reported, both giving optically active phosphines with low enantiomeric excesses.
