551935-59-2Relevant academic research and scientific papers
Hammond Postulate Mirroring Enables Enantiomeric Enrichment of Phosphorus Compounds via Two Thermodynamically Interconnected Sequential Stereoselective Processes
Rajendran, Kamalraj V.,Nikitin, Kirill V.,Gilheany, Declan G.
supporting information, p. 9375 - 9381 (2015/08/06)
(Figure Presented). The dynamic resolution of tertiary phosphines and phosphine oxides was monitored by NMR spectroscopy. It was found that the stereoselectivity is set during the formation of the diastereomeric alkoxyphosphonium salts (DAPS), such that t
Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts
Al Sulaimi, Sulaiman S.,Rajendran, Kamalraj V.,Gilheany, Declan G.
supporting information, p. 5959 - 5965 (2015/09/22)
We report LiBH4 as a preferred, simple and effective reagent for reductive boronation of achiral and racemic chlorophosphonium salts (CPS) and for diastereomeric alkoxyphosphonium salts (DAPS), both of which are, in turn, easily generated from either the corresponding phosphane or, more conveniently, the phosphane oxide. Further, we have shown that the DAPS reduction/boronation could be achieved with complete stereocontrol to give scalemic phosphane-borane directly in excellent yield and enantiomeric excess (ee). This new methodology was employed to investigate the effects of aryl substitution on the outcome of dynamic kinetic resolution of arylmethylphenylphosphanes and phosphane oxides via DAPS. It was found that substitution at the ortho position strongly affects the degree of stereoselection. However, surprisingly, we confirmed that there was no variation of stereoselectivity seen with the electronic effect of substituents on the para position.
P -stereogenic phospholanes or phosphorinanes from o -biarylylphosphines: Two bridges not too far
Mohar, Barbara,?usak, Alen,Modec, Barbara,Stephan, Michel
, p. 4665 - 4673 (2013/07/19)
The discovery of a concise regiodivergent asymmetric route to nonclassical P-stereogenic 5- or 6-membered benzophosphacycles, under conditions-dependent radical (oxidative addition) versus anionic (SNAr) benzannulation, is reported.
Catalyzing pyramidal inversion: Configurational lability of P-stereogenic phosphines via single electron oxidation
Reichl, Kyle D.,Ess, Daniel H.,Radosevich, Alexander T.
supporting information, p. 9354 - 9357 (2013/07/25)
We report that pyramidal inversion of trivalent phosphines may be catalyzed by single electron oxidation. Specifically, a series of P-stereogenic (aryl)methylphenyl phosphines are shown to undergo rapid racemization at ambient temperature when exposed to catalytic quantities of a single electron oxidant in solution. Under these conditions, transient phosphoniumyl radical cations (R3P?+) are formed, and computational models indicate that the pyramidal inversion barriers for these open-shell intermediates are on the order of ～5 kcal/mol. The observed 1020-fold rate enhancement over uncatalyzed pyramidal inversion opens new opportunities for the dynamic stereochemistry of phosphines and may hold additional implications for the configurational stability of P-stereogenic phosphine ligands on high-valent oxidizing transition metals.
PROCESSES FOR THE STEREOSELECTIVE PREPARATION OF P-CHIRAL FOUR -COORDINATED PHOSPHORUS BORANE COMPOUNDS AND P-CHIRAL THREE-COORDINATED PHOSPHORUS COMPOUNDS
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Page/Page column 64-65, (2012/09/11)
Processes for the stereoselective preparation of P-chiral four-coordinated phosphorus borane compounds and P-chiral three-coordinated phosphorus compounds.
Identification of a key intermediate in the asymmetric Appel process: One pot stereoselective synthesis of P-stereogenic phosphines and phosphine boranes from racemic phosphine oxides
Rajendran, Kamalraj V.,Gilheany, Declan G.
supporting information, p. 10040 - 10042 (2012/11/07)
Sequential treatment of racemic phosphine oxides with oxalyl chloride and chiral non-racemic alcohol generates the same ratios of diastereomeric alkoxyphosphonium salts obtained in the corresponding asymmetric Appel process, strongly implicating the intermediate chlorophosphonium salt in the stereoselecting step. Subsequent reduction allows a novel synthesis of enantioenriched P-stereogenic phosphines-phosphine boranes. The Royal Society of Chemistry 2012.
A U-turn in the asymmetric appel reaction: Stereospecific reduction of diastereomerically enriched alkoxyphosphonium salts allows the asymmetric synthesis of P-stereogenic phosphanes and phosphane boranes
Rajendran, Kamalraj V.,Kudavalli, Jaya S.,Dunne, Katherine S.,Gilheany, Declan G.
supporting information; experimental part, p. 2720 - 2723 (2012/07/14)
An efficient one-pot synthesis has been developed of enantioenriched P-stereogenic phosphanes and phosphane boranes from the corresponding racemic phosphanes in excellent yield under asymmetric Appel conditions. The chiral auxiliary (menthol) can also be recovered unchanged. The simple and efficient protocol significantly expands the scope of our asymmetric Appel process. The crucial step in the preparation involves stereospecific reduction of intermediate diastereomeric alkoxyphosphonium salts, which are obtained in the reaction of phosphane, hexachloroacetone, and menthol. Thereby, reaction with LiAlH4 or NaBH4 gives the corresponding phosphanes or phosphane boranes, respectively. Copyright
Simple unprecedented conversion of phosphine oxides and sulfides to phosphine boranes using sodium borohydride
Rajendran, Kamalraj V.,Gilheany, Declan G.
supporting information; experimental part, p. 817 - 819 (2012/02/03)
A variety of phosphine oxides and sulfides can be efficiently converted directly to the corresponding phosphine boranes using oxalyl chloride followed by sodium borohydride. Optically active P-stereogenic phosphine oxides can be converted stereospecifically to phosphine boranes with inversion of configuration by treatment with Meerwein's salt followed by sodium borohydride.
Allylpalladium complexes with P-stereogenic monodentate phosphines. Application in the asymmetric hydrovinylation of styrene
Grabulosa, Arnald,Mueller, Guillermo,Ordinas, Juan I.,Mezzetti, Antonio,Maestro, Miguel Angel,Font-Bardia, Merce,Solans, Xavier
, p. 4961 - 4973 (2008/10/09)
A group of P-stereogenic monodentate phosphines S-PPhRR' (R = 1-naphthyl, 9-phenan-thryl, or o-biphenylyl and R' = CH3-, i-C3R 3-, and Ph3SiCH2-) have been prepared by succesive substitution reactions on the oxazaphospholidineborane obtained from (-)ephedrine and bis(N,N-diethylamino)phenylphosphine. The reaction with binuclear allyl compounds [Pd(μ-Cl)(allyl)]2 gives neutral [PdCl(allyl)P*] complexes. When allyl = 2-CH3-CsH4 (5), two isomers appeared in solution due to the R- or S-geometry around the palladium atom. The discrimination effect of the phosphines is small and the maximum isomeric ratio is observed for PPh(o-Ph2)(CH 2SiPh3). The molecular structure determined by X-ray diffraction of two complexes with P* = PPh(o-Ph2)(i-Pr) and PPh(o-Ph2)(OMe) showed a very similar nonsymmetric coordination of the allyl moiety according to the greater trans influence of the phosphorus atom. When allyl = 1-C6H5-C3H4 (6), the NMR spectroscopy showed up to four isomers due to the R- or S-geometry around palladium and the Z- or E-disposition of P* and the phenyl substituent of the allyl moiety. The E-isomers are the major species in solution, unique with PPh(o-Ph2)(CH2SiPh3). The usual, well-defined dynamic exchanges by π-σ-π and pseudorotation of the allyl moiety have been observed. The codimerization reaction between styrene and ethylene has been tested using filtered CH2Cl2 solutions of [PdCl(2-CH3-C3H4)P*] (5) complexes and AgBF4 as catalytic precursors. Moderate activity (TOF -1 at 25 °C) and good selectivities to 3-Ph-l-butene (-90% at 80% conversion) are obtained. The ee is moderate (a potentially secondary coordination atom occurs only when the substitution is in the phenyl ring and without significant improvements of the ee.
