Systematic survey of positive chlorine sources in the asymmetric Appel reaction: oxalyl chloride as a new phosphine activator

Rajendran, Kamalraj V.; Kennedy, Lorna; O’Connor, Cormac T.; Bergin, E.; Gilheany, Declan G.

doi:10.1016/j.tetlet.2013.10.044

Cited by 18 publications

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“…The system is based on the reaction of a chlorophosphonium salt (CPS) with chiral non‐racemic alcohol to generate a high yield of diastereomerically enriched alkoxyphosphonium salt (DAPS). The CPS can be generated under either Appel conditions from the phosphane4a,4c or by reaction of the oxide with oxalyl chloride 4d,4e. We propose that the dynamic nature of the resolution arises through the extremely rapid interconversion of the enantiomers of the CPS 5.…”

Section: Introductionmentioning

confidence: 99%

Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

2015

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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.

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Section: Introductionmentioning

confidence: 99%

Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

2015

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“…[11] Our current method involves the chlorination of either rac-1 or rac-2 to form enantiomeric chlorophosphonium salts (CPSs) 3, [12] which, according to the present hypothesis, rapidly interconvert and are dynamically resolved in the presence of a chiral auxiliary, such as menthol, to give the diastereomeric alkoxyphosphonium salt (DAPS) 4 (path b). [13] The final ee of scalemic 1 formed by Arbuzov collapse of 4 (path c) is limited by the diastereomeric purity, de, of 4.…”

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Turning Regioselectivity into Stereoselectivity: Efficient Dual Resolution of P‐Stereogenic Phosphine Oxides through Bifurcation of the Reaction Pathway of a Common Intermediate

et al. 2014

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Synthetic routes that provide facile access to either enantiomeric form of a target compound are particularly valuable. The crystallization-free dual resolution of phosphine oxides that gives highly enantioenriched materials (up to 94 % ee) in excellent yields is reported. Both enantiomeric oxides have been prepared from a single intermediate, (RP )-alkoxyphosphonium chloride, which is formed in the course of a selective dynamic kinetic resolution using a single enantiomer of menthol as the chiral auxiliary. The origin of the dual stereoselectivity lies in bifurcation of the reaction pathway of this intermediate, which works as a stereochemical railroad switch. Under controlled conditions, Arbuzov-type collapse of this intermediate proceeds through CO bond fission with retention of the configuration at the phosphorus center. Conversely, alkaline hydrolysis of the PO bond leads to the opposite SP enantiomer.

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“…The pseudo-rotation of ligands at the P(V) atom leads to the formation of the most thermodynamically stable diastereomer of the halogen-phosphonium intermediate, which then turns into one diastereomer of the final product (Equation (69)) [89]. (69) Gilheany et al [91][92][93][94] carried out the asymmetric Appel reaction by oxidizing tertiary phosphines with polyhaloalkanes in the presence of chiral L-menthol. As a result, chiral phosphine oxides were obtained with a good ee.…”

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“…This phosphine oxide by reaction with LDA and copper chloride was converted to the DiPAMP analog, which is used in asymmetric catalysis. A chiral bis-(R,R)phosphine oxide was obtained with 98% ee and a small amount of the meso isomer impurity was (69) Gilheany et al [91][92][93][94] carried out the asymmetric Appel reaction by oxidizing tertiary phosphines with polyhaloalkanes in the presence of chiral L-menthol. As a result, chiral phosphine oxides were obtained with a good ee.…”

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“…Interesting synthesis routes, providing access to both enantiomers of the reaction product, were developed using double separation of phosphine oxides, which afforded enantiomerically enriched products in yields up to 94% ee. The synthesis of diastereomeric alkoxyphosphonium salts was achieved by dynamic separation of racemic phosphines in reaction with hexachloroacetone and menthol as shown in Equation (71) [94].…”

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Asymmetric Electrophilic Reactions in Phosphorus Chemistry

Kolodiazhna

Kolodiazhnyi

2020

Symmetry

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This review is devoted to the theoretic and synthetic aspects of asymmetric electrophilic substitution reactions at the stereogenic phosphorus center. The stereochemistry and mechanisms of electrophilic reactions are discussed—the substitution, addition and addition-elimination of many important reactions. The reactions of bimolecular electrophilic substitution SE2(P) proceed stereospecifically with the retention of absolute configuration at the phosphorus center, in contrast to the reactions of bimolecular nucleophilic substitution SN2(P), proceeding with inversion of absolute configuration. This conclusion was made based on stereochemical analysis of a wide range of trivalent phosphorus reactions with typical electrophiles and investigation of examples of a sizeable number of diverse compounds. The combination of stereospecific electrophilic reactions and stereoselective nucleophilic reactions is useful and promising for the further development of organophosphorus chemistry. The study of phosphoryl group transfer reactions is important for biological and molecular chemistry, as well as in studying mechanisms of chemical processes involving organophosphorus compounds. New versions of asymmetric electrophilic reactions applicable for the synthesis of enantiopure P-chiral secondary and tertiary phosphines are discussed.

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Systematic survey of positive chlorine sources in the asymmetric Appel reaction: oxalyl chloride as a new phosphine activator

Cited by 18 publications

References 41 publications

Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

Turning Regioselectivity into Stereoselectivity: Efficient Dual Resolution of P‐Stereogenic Phosphine Oxides through Bifurcation of the Reaction Pathway of a Common Intermediate

Asymmetric Electrophilic Reactions in Phosphorus Chemistry

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Systematic survey of positive chlorine sources in the asymmetric Appel reaction: oxalyl chloride as a new phosphine activator

Cited by 18 publications

References 41 publications

Lithium Borohydride for Achiral and ­Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

Lithium Borohydride for Achiral and ­Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

Turning Regioselectivity into Stereoselectivity: Efficient Dual Resolution of P‐Stereogenic Phosphine Oxides through Bifurcation of the Reaction Pathway of a Common Intermediate

Asymmetric Electrophilic Reactions in Phosphorus Chemistry

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Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts

Lithium Borohydride for Achiral and Stereospecific Reductive Boronation at Phosphorus: Lack of Electronic Effects on Stereoselective Formation of Alkoxyphosphonium Salts