Preparation of Vinylphosphonates from Ketones Promoted by TfO.

An efficient triflic anhydride promoted phosphorylation of ketone was disclosed, and vinylphosphorus compounds were prepared under solvent- and metal-free conditions. Both aryl and alkyl ketones could perform smoothly to give vinyl phosphonates in high to excellent yields. In addition, the reaction was easy to carry out and easy to scale up.

Direct phosphorylation of benzylic C-H bonds under transition metal-free conditions forming spC-P bonds.

Direct phosphorylation of benzylic C-H bonds was achieved in a biphasic system under transition metal-free conditions. A selective radical/radical spC-H/P(O)-H cross coupling was proposed, and various substituted toluenes were applicable. The transformation provided a promising method for constructing spC-P bonds.

Markovnikov-addition of H-phosphonates to terminal alkynes under metal- and solvent-free conditions.

An addition of H-phosphonates to aryl alkynes was realized under solvent- and metal-free conditions, affording Markovnikov-selective α-vinylphosphonates in moderate to good yields. A wide range of aryl alkynes could be applied for the reaction. A tentative mechanism of addition-substitution was proposed based on P {H} NMR studies.

The stereoselective conversion of epimerized alkoxyl phosphine-borane to -stereogenic tertiary phosphine cleavage of P-O bond.

The P-O bond of epimerized alkoxyl phosphine-borane was cleaved by naphthalene-lithium, to form two diastereomers of P-anions in a ratio of 86 : 14, which was then converted to secondary phosphine-borane acidification, and to tertiary phosphines with alkyl halides with enhanced 96 : 4 dr. The isolated tertiary phosphine containing hydroxyl (in >99 : 1 dr) was converted to multi-stereogenic tertiary phosphines -alkylation with alkylene dihalides.

Cleavage of Aromatic C-O Bonds via Intramolecular SAr Reaction and Preparation of ,,-Stereogenic Menthyl Phosphine Derivatives.

Phosphine ligands with up to six chiral sites were prepared, starting from 2-phenylphenol, via - and -alkylation, cyclization, and coupling. The chirality was transferred from ()-menthyl to phosphorus, α-carbon, and axis, to achieve excellent diastereoselectivities. During an intramolecular SAr reaction with alkoxyl as the leaving groups, the C-O bond was converted to a C-C bond.

Stereoselective preparation of P,axial-stereogenic allenyl bisphosphine oxides via chirality-transfer.

P,C-Stereogenic propargyl alcohols RC-3/SC-3' were prepared by the addition of (L)-menthyl-derived SPOs to propynals, which were converted to P,axial-stereogenic allenyl bisphosphine oxides. The chirality transfer was controlled by α-carbon via syn [2,3]-sigmatropic rearrangement. For SC-3' linking weak WDG on the alkynyl moiety, the chirality on the axis depended on stereogenic phosphorus.

Functional Phosphine Derivatives Having Stationary and Flexible Chiralities: Their Preparation and Chirality Controlling.

Various functional secondary and tertiary phosphines, or their derivatives, containing stationary chiral phosphorus and flexible chiral axis were prepared, which could be further modified to afford diversely chelating ligands. The flexible axial chirality was fixed by stereogenic phosphorus via a cyclic linkage of chemical bonds or coordination with a metallic ion.

Hydrophosphorylation of Alkynes Catalyzed by Palladium: Generality and Mechanism.

We carried out a comprehensive study on the generality, scope, limitations, and mechanism of the palladium-catalyzed hydrophosphorylation of alkynes with P(O)-H compounds (i.e., H-phosphonates, H-phosphinates, secondary phosphine oxides, and hypophosphinic acid).

Metal-Free One-Pot Synthesis of 3-Phosphinoylbenzofurans via Phospha-Michael Addition/Cyclization of H-Phosphine Oxides and in Situ Generated ortho-Quinone Methides.

A novel metal-free one-pot protocol for the effective and efficient synthesis of 3-phosphinoylbenzofurans via a phospha-Michael addition/cyclization of H-phosphine oxides and in situ generated ortho-quinone methides is described. Based on the expeditious construction of C(sp)-P bonds, asymmetric synthesis of optically pure 3-phosphinoylbenzofurans containing chiral P-stereogenic center has also been probed by using chiral R-(-)-menthyl phenylphosphine oxide.

Reinvestigation of the Substitutions Reaction of Stereogenic Phosphoryl Compounds: Stereochemistry, Mechanism, and Applications.

Nucleophilic substitutions at P centers are of high importance in biological processes and asymmetric synthesis. However, detailed studies on this topic are rare. P-Stereogenic compounds containing P-Cl, P-O, and P-S bonds were diastereoselectively prepared and then used to study the substitution of Cl, O, and S at phosphorus centers with organometallic reagents.

Nucleophilic Substitution of P-Stereogenic Chlorophosphines: Mechanism, Stereochemistry, and Stereoselective Conversions of Diastereomeric Secondary Phosphine Oxides to Tertiary Phosphines.

A diastereomeric mixture of secondary phosphine oxide is stereospecifically converted to chlorophosphine salt by treatment with oxalyl chloride, which stereoselectively affords P-inverted or retained tertiary phosphines, depending on the substitution with aliphatic or aromatic Grignard reagents, respectively, in high to 99% yield and 99:1 dr. The repulsion of π-electron on aryl to lone electron pair on phosphorus is proposed for the P-retained substitution.

Nonepimerizing Alkylation of H-P Species to Stereospecifically Generate P-Stereogenic Phosphine Oxides: A Shortcut to Bidentate Tertiary Phosphine Ligands.

The secondary R-(-)-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 ZnCl-NaBH 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.

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 Preparations of P-Stereogenic Phosphonothioates and Phosphonoselenoates.

P-Stereogenic phosphonothioates and phosphonoselenoates were readily prepared utilizing RP-menthyl phenylphosphite 1 by two methods. The first method used elemental sulfur or selenium to react with 1, followed by alkylation of the intermediates with alkyl halides. The second used 1 to react with disulfide or diselenide.

Variable mechanism of nucleophilic substitution of P-stereogenic phosphoryl chloride with alkynyl metallic reagents.

The variable mechanism for substitution of P-stereogenic phosphoryl chloride with alkynyl metallic reagents, which depends on temperature, stoichiometry of starting materials, and the structure of the nucleophilic reagent, is assumed as either SN2-like or Berry pseudorotation of pentacoordinated phosphorus intermediates, affording inversion and retention products, respectively. The formation of the inversion product can be controlled to occur predominantly to afford (RP)-alkynylphosphinates.

Double Asymmetric Induction During the Addition of (RP)-Menthyl Phenyl Phosphine Oxide to Chiral Aldimines.

P,C-Stereogenic α-amino phosphine oxides were prepared from the addition of (RP )-menthyl phenyl phosphine oxide to chiral aldimines under neat condition at 80 °C in up to 91:9 drC and 99% yields. The diastereoselectivity was mainly induced by chiral phosphorus that showed matched or mismatched induction with (S)- or (R)-aldimines, respectively.

One-pot process that efficiently generates single stereoisomers of 1,3-bisphosphinylpropanes having five chiral centers.

P,C-stereogenic 1,3-bisphosphinylpropanes 3 that have up to five stereogenic centers could be obtained stereoselectively in high yields by a one-step reaction of (RP)-menthylphenylphosphine oxide 1 with α,β-unsaturated aldehydes 2 catalyzed by KOH at room temperature. A mechanism was proposed as to involve a stereoselective intermolecular 1,3'-phosphorus migration from the 1,2-adduct of 1 with 2 to another 2 generating a 1,4-adduct that subsequently reacts with 1 to produce 3.

Facile base-mediated redox transformation: an efficient strategy for the synthesis of α-acyloxyphosphoryl compounds.

An efficient one-pot synthesis of α-acyloxyphosphoryl compounds from aldehydes and hydrogen phosphoryl compounds has been developed using a facile base-mediated redox strategy. This redox transformation is applicable to synthesize a wide range of valuable α-acyloxyphosphoryl compounds with high atom- and step-economic efficiency.

Addition of optically pure H-phosphinate to ketones: selectivity, stereochemistry and mechanism.

Aromatic methyl ketones and cyclic asymmetric ketones underwent hydrophosphorylation with P-stereogenic H-P species in the presence of potassium carbonate to produce P,C-stereogenic tertiary α-hydroxyl phosphinates in excellent yields with up to 99 : 1 dr. The diastereoselectivity was induced by a reversible conversion of less stable stereomer of product to that of a more stable one via an equilibrium, which was confirmed by aldehyde/ketone exchanging reaction. Toward the exchange, aliphatic or aldehyde carbonyl were more active than aromatic or ketone carbonyls, respectively.

Stereogenic phosphorus-induced diastereoselective formation of chiral carbon during nucleophilic addition of chiral H-P species to aldehydes or ketones.

P,C-stereogenic α-hydroxyl phosphinates or phosphine oxides were prepared from the additions of (RP)-phosphinate to ketones or (RP)-phosphine oxide to aldehydes, respectively, catalyzed by bases at room temperature in up to >99:1 diasteromeric ratio (d.r.P/d.

Transition metal-catalyzed efficient and green transformations of P(O)-H compounds to functional organophosphorus compounds.

Organophosphorus compounds are of high importance in organic synthesis, catalysis, biochemistry, pharmaceuticals, and material science. In this mini review, we summarize our recent studies on transition metal-catalyzed green and atom efficient transformations of P(O)-H bonds to various versatile organophosphorus compounds, including the highly regio- and stereoselective P(O)-H additions to carbon-carbon unsaturated compounds, asymmetric hydrophosphorylation reactions, and dehydrogenative coupling reactions of P(O)-H compounds with carbon-H and heteroatom-H compounds. These new reactions provide efficient, general and practical ways for the preparation of a variety of well-defined functional organophosphorus compounds.

(1-Methyl-1H-imidazol-3-ium-2-yl)(phen-yl)phosphinate monohydrate.

The title compound, C(10)H(11)N(2)O(2)P·H(2)O, contains a tetra-coordinate penta-valent P atom. The phosphinate group plays a predominant role in the cohesion of the crystal structure by forming chains along the b axis via inter-molecular C-H⋯O hydrogen bonds. These chains are connected by O-H⋯O and N-H⋯O hydrogen bonding involving the lattice water.

(R(P))-5-Methyl-2-(propan-2-yl)cyclo-hexyl phen-yl{phen-yl[(1-phenyl-eth-yl)amino]-meth-yl}phosphinate.

In the title compound, C(31)H(40)NO(2)P, the P atom has a distorted tetra-hedral stereochemistry [bond-angle range about P = 103.33 (6)-115.24 (15)°] and has R(P) chirality, which was confirmed crystallographically.