97764-41-5Relevant academic research and scientific papers
Reduction of tertiary phosphine oxides to phosphine-boranes using Ti(Oi-Pr)4/BH3-THF
Sowa, Sylwia,Pietrusiewicz, K. Micha?
supporting information, (2021/03/17)
A new method for reduction of tertiary phosphine oxides leading to the formation of tertiary phosphine-boranes has been developed. The BH3-THF/Ti(Oi-Pr)4 reducing system enables conversion of triaryl, diarylalkyl and trialkylphosphine oxides directly to their borane analogues in good to high yields. In contrast to the previously reported protocols, the presence of activating groups in the structure of starting material is not necessary for the reaction to occur. The reaction is highly stereoselective and proceeds with predominant retention of configuration at the phosphorus atom. A plausible mechanism of reduction of the P[dbnd]O bond by BH3-THF/Ti(Oi-Pr)4 has been proposed.
Iridium-catalyzed enantioselective C-H borylation of diarylphosphinates
Song, Shu-Yong,Li, Yinwu,Ke, Zhuofeng,Xu, Senmiao
, p. 13445 - 13451 (2021/11/16)
P-stereogenic phosphorus compounds are a ubiquitous and critically important class of chiral ligands in asymmetric catalysis. Methods for catalytic asymmetric synthesis via a step- and atom-economic way are still very limited. We herein disclose a protocol of phosphinate-directed iridium-catalyzed enantioselective ortho-H borylation to construct P-stereogenic phosphorus compounds. A number of functional groups could be well tolerated to afford optically active diarylphosphinates with good to excellent enantioselectivities (up to 92% ee). We also demonstrate the synthetic utilities of the obtained borylated products, including the synthesis of precursors for chiral phosphine ligands.
Enantiodivergent Formation of C-P Bonds: Synthesis of P-Chiral Phosphines and Methylphosphonate Oligonucleotides
Baran, Phil S.,Eastgate, Martin D.,Knouse, Kyle W.,Padial, Natalia M.,Rivas-Bascón, Nazaret,Schmidt, Michael A.,Vantourout, Julien C.,Xu, Dongmin,Zheng, Bin
supporting information, (2020/03/30)
Phosphorus Incorporation (PI, abbreviated Π) reagents for the modular, scalable, and stereospecific synthesis of chiral phosphines and methylphosphonate nucleotides are reported. Synthesized from trans-limonene oxide, this reagent class displays an unexpected reactivity profile and enables access to chemical space distinct from that of the Phosphorus-Sulfur Incorporation reagents previously disclosed. Here, the adaptable phosphorus(V) scaffold enables sequential addition of carbon nucleophiles to produce a variety of enantiopure C-P building blocks. Addition of three carbon nucleophiles to Π, followed by stereospecific reduction, affords useful P-chiral phosphines; introduction instead of a single methyl group reveals the first stereospecific synthesis of methylphosphonate oligonucleotide precursors. While both Π enantiomers are available, only one isomer is required - the order of nucleophile addition controls the absolute stereochemistry of the final product through a unique enantiodivergent design.
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.
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, (2012/09/11)
Processes for the stereoselective preparation of P-chiral four-coordinated phosphorus borane compounds and P-chiral three-coordinated phosphorus compounds.
Simple unprecedented conversion of phosphine oxides and sulfides to phosphine boranes using sodium borohydride
Rajendran, Kamalraj V.,Gilheany, Declan G.
, 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.
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
Asymmetric synthesis of SMS-Phos series' precursor and a naphthalene analogue
Stephan, Michel,Modec, Barbara,Mohar, Barbara
, p. 1086 - 1089 (2011/04/15)
An efficient and high-yielding (up to 57% overall yield) asymmetric route to enantiopure P-stereogenic 1,2-bis[(o-hydroxyaryl)(phenyl)phosphino-P-borane] ethanes wherein aryl = phenyl and naphthyl, is presented. The occurring P-stereomutation is confirmed
