The Experts below are selected from a list of 1986 Experts worldwide ranked by ideXlab platform
Gérard Buono - One of the best experts on this subject based on the ideXlab platform.
-
Reduction of secondary and Tertiary Phosphine oxides to Phosphines
Chemical Society Reviews, 2015Co-Authors: Damien Hérault, Duc Hanh Nguyen, Didier Nuel, Gérard BuonoAbstract:Achiral or chiral Phosphines are widely used in two main domains: ligands in organometallic catalysis and organocatalysis. For this reason, the obtention of optically pure Phosphine has always been challenging in the development of asymmetric catalysis. The simplest method to obtain Phosphines is the reduction of Phosphine oxides. The essential difficulty is the strength of the P=O bond which involves new procedures to maintain a high chemio- and stereoselectivity. The reduction can occur with retention or inversion of the stereogenic phosphorus atom depending on the nature of the reducing agent and the presence of additives. In fact, the reactivity of the Phosphine oxides and the mechanism of the reduction are not always well understood. Since the first work in the 1950's, numerous studies have been realised in order to develop methodologies with different reagents or to understand the mechanism of the reaction. In the last decade, efficient stereospecific methodologies have been developed to obtain optically pure Tertiary Phosphines from P-stereogenic Phosphine oxides. In this review, we intend to provide a comprehensive and critical overview of these methodologies.
-
Bulky, optically active P-stereogenic Phosphine-boranes from pure H-menthylphosphinates.
Journal of the American Chemical Society, 2011Co-Authors: David Gatineau, Laurent Giordano, Gérard BuonoAbstract:The transformation of readily available pure-H-menthylphosphinates into chiral phosphinous acid-boranes permits the elaboration of bulky P-stereogenic secondary Phosphine–boranes. Taking advantage of the synthetic potential of these compounds, a broad range of hindered P-chiral Tertiary Phosphine–boranes has been prepared with excellent enantiomeric excesses. The utility of bulky o-tolylPhosphines was illustrated by the synthesis of a rare enantiopure phosphapalladacycle (SP,SP)-12.
Chang-qiu Zhao - One of the best experts on this subject based on the ideXlab platform.
-
Nonepimerizing Alkylation of H–P Species to Stereospecifically Generate P‑Stereogenic Phosphine Oxides: A Shortcut to Bidentate Tertiary Phosphine Ligands
2017Co-Authors: Shao-zhen Nie, Zhong-yang Zhou, Ji-ping Wang, Hui Yan, Jing-hong Wen, Yun-yao Cui, Chang-qiu ZhaoAbstract:The secondary RP-(−)-menthyl alkylPhosphine oxide was confirmed as configurationally stable toward base and was used in base-promoted alkylation, stereospecifically affording P-retained bis or functional Tertiary Phosphine oxides in excellent yields. The alkylated products were deoxygenated using oxalyl chloride followed by ZnCl2–NaBH4 to form P-inversed bidentate Phosphine boranes in high stereoselectivities
-
preparation of optically pure Tertiary Phosphine oxides via the addition of p stereogenic secondary Phosphine oxide to activated alkenes
Journal of Organic Chemistry, 2016Co-Authors: Ji-ping Wang, Zhong-yang Zhou, Shao-zhen Nie, Jing-hong Wen, Chang-qiu ZhaoAbstract:Functionalized P,C-stereogenic Tertiary Phosphine oxides were prepared by the addition of (RP)-menthyl phenylPhosphine oxide to activated olefins, in high drP and drC, and were isolated in excellent yields. The reaction was readily catalyzed by Ca(OH)2 or occurred with gentle heating. A wide range of substrates, including vinyl ketones, esters, nitriles, and nitro alkenes, can be used in the reaction.
-
Preparation of Optically Pure Tertiary Phosphine Oxides via the Addition of P‑Stereogenic Secondary Phosphine Oxide to Activated Alkenes
2016Co-Authors: Ji-ping Wang, Zhong-yang Zhou, Shao-zhen Nie, Jing-hong Wen, Chang-qiu ZhaoAbstract:Functionalized P,C-stereogenic Tertiary Phosphine oxides were prepared by the addition of (RP)-menthyl phenylPhosphine oxide to activated olefins, in high drP and drC, and were isolated in excellent yields. The reaction was readily catalyzed by Ca(OH)2 or occurred with gentle heating. A wide range of substrates, including vinyl ketones, esters, nitriles, and nitro alkenes, can be used in the reaction
-
stereospecific nucleophilic substitution of optically pure h phosphinates a general way for the preparation of chiral p stereogenic Phosphine oxides
Journal of the American Chemical Society, 2008Co-Authors: Chang-qiu Zhao, Li-biao HanAbstract:Contrary to the generally held view, it is found that the rapid epimerization of (−)-menthyl (RP)-phenylphosphinate under basic conditions is not due to the so far believed inherent stereolability of its corresponding anion but due to a reaction of the hydrogen phosphinate ester with a metal alkoxide. This finding successfully leads to a discovery that, by adding an H-phosphinate to organolithiums or Grignard reagents at a low temperature, the nucleophilic substitution of the alkoxy group of the H-phosphinate with organolithiums or Grignard reagents proceeds stereospecifically with inversion of configurations at phosphorus to give a wide range of P-stereogenic secondary Phosphine oxides and Tertiary Phosphine oxides, by quenching the reaction mixture with water and alkyl halides, respectively. This finding establishes a general protocol for the preparation of optically active secondary Phosphine oxides and Tertiary Phosphine oxides from the easily accessible optically pure H-phosphinates. Mechanistic stud...
Kui Yuan - One of the best experts on this subject based on the ideXlab platform.
-
chiral Phosphine squaramides as enantioselective catalysts for the intramolecular morita baylis hillman reaction
ChemInform, 2011Co-Authors: Hong-liang Song, Kui YuanAbstract:Novel squaramides (I) containing a Tertiary Phosphine are developed and tested in the title reaction of ω-formyl-enone (II).
-
chiral Phosphine squaramides as enantioselective catalysts for the intramolecular morita baylis hillman reaction
Chemical Communications, 2011Co-Authors: Hong-liang Song, Kui YuanAbstract:Novel squaramides containing Tertiary Phosphine were developed as chiral bifunctional organic catalysts to promote the asymmetric intramolecular Morita–Baylis–Hillman reaction of ω-formyl-enones. The adducts were obtained in high yields with good-to-excellent enantioselectivity (up to 93% ee).
Martin A Bennett - One of the best experts on this subject based on the ideXlab platform.
-
ortho metallated transition metal complexes derived from Tertiary Phosphine and arsine ligands
Coordination Chemistry Reviews, 2006Co-Authors: Fabian Mohr, Steven H Priver, Suresh K Bhargava, Martin A BennettAbstract:Abstract This article reviews the synthesis, reactivity and structure of transition metal complexes containing ortho -metallated Tertiary Phosphines and arsines of the type [2-R 2 EC 6 H 4 ] − (E = P, As; R = various substituents). Available synthetic routes are summarized and some general spectroscopic and structural features are discussed. In subsequent sections, ortho -metallated complexes of this type are reviewed, arranged according to the triads of the d-block series. The literature has been covered to the end of 2004. The Appendix lists all known mononuclear, binuclear and trinuclear ortho -metallated transition metal complexes which have been structurally characterized by X-ray diffraction.
Junliang Zhang - One of the best experts on this subject based on the ideXlab platform.
-
p chiral Phosphines enabled by palladium xiao phos catalyzed asymmetric p c cross coupling of secondary Phosphine oxides and aryl bromides
Journal of the American Chemical Society, 2019Co-Authors: Qiang Dai, Junliang ZhangAbstract:The development of transition-metal-catalyzed methods for the synthesis of P-chiral Phosphine derivatives poses a considerable challenge. Herein, we present a direct Pd/Xiao-Phos-catalyzed cross-coupling reaction of easily accessible secondary Phosphine oxides and aryl bromides, which provides rapid access to P-chiral Phosphine oxides. The reaction proceeds efficiently with a wide array of reaction partners to deliver various Tertiary Phosphine oxides in up to 96% yield and 97% ee. Moreover, the synthesis of DiPAMP ligand and its analogues was also realized, which demonstrates a suitable pathway to switching the branched chain of DiPAMP.