The Concept of P--H Protection Extended to Phosphine Oxides: Preparation of Functional,Unsymmetrical Secondary and Tertiary Phosphine Oxides

Phosphine oxide analogues of Triazole fungicides and protected Threonine have been prepared. The enzymatic hydrolysis of phosphine oxide di-acetates has been investigated.     

Synthesis of P-Stereogenic Phosphine Oxides via Nickel-Catalyzed Asymmetric Cross-Coupling of Secondary Phosphine Oxides with Alkenyl and Aryl Bromides

A general and mild nickel-catalyzed enantioselective C(sp²)−P cross-coupling for synthesizing P-stereogenic phosphine oxides has been developed. The asymmetric alkenylation/arylation of racemic secondary phosphine oxides with alkenyl/aryl bromides generated P-stereogenic phosphine oxides with high yields and enantioselectivities. Various functional groups were tolerated, and the applications of this method were demonstrated through late-stage functionalization and product transformations.     

Phosphorylation of Furfural by Secondary Phosphine Oxides

Nucleophilic addition of secondary phosphine oxides to furfural takes place under mild conditions and gives quantitative yields of 2-(diorganylphosphorylhydroxymethyl)furans, which are polyfunctional building blocks for organic synthesis and prospective amphiphilic ligands for the design of metal complex catalysts.     

Synthesis of Tertiary Bisphosphine Oxides from Methylacetylene and Secondary Phosphine Oxides

Russian Journal of Organic Chemistry -     

The Reactions of Dialkyl Phosphites and Phosphine Oxides with Iodosylbenzene

The reaction of iodosylbenzene with >P(O)H type of acids (dialkyl phosphites, secondary phosphine oxides) was studied. The acids of >P(O)H type add to iodosylbenzene to yield intermediate 6 which in the aprotic solvents yields oxidation products, it means >P(O)OH acids and/or anhydride of >P(O)OP(O)< type. On the other hand if the reaction is performed in alcohol as a solvent in the presence of sodium alcoholate >P(O)OR ester is the major product.     

Tertiary Phosphine Oxides in Reaction with Benzaldehyde

Symmetrical and unsymmetrical tertiary phosphine oxides containing benzyl and 5-chloro-2-thienyl radicals stereoselectively react with benzaldehyde in the sodium amide-THF system to form the E isomers of 1-organyl-2-phenylethene and diorganylphosphinic acids in high yields. Triethyl, tris(2-phenyl- ethyl)-, and tris[(4-methoxyphenyl)methyl]phosphine oxides under the above-mentioned conditions do not react with benzaldehyde.     

New Dimethyl(Methylenoxyaryl)Phosphine Oxides

Abstract

In the poster presentation is reported the preparation of the new dimethyl(methylenoxyaryl)phosphine oxides via ZVilliamson reaction from dimethyl-chloromethyl-phoaphine oxide and sodium solts of the coresponding phenols: l-di-methylphosphinylmethylenoxy-4-methyl-2,6-bis(l,l -dimethylethyl)benzene; 1,3-bis(dimethylphosphinylmethylenOxy)benzene; 1,4-bis(dimethylphosphinylmethylenoxy)ben-zene; 1,3,5-tris(dimethylphosphinylmethylenoxy)benzene; 1,2,3-tris(dimethylphosphinylmethylenoxy～benzene; 2,2′-methylene-bia(6-tert-butyl-4-methyl-l-dimethyl-phosphinylmethylenoxybenzene); 2,2′-rnethylene-bis-(6-tert-butyl-4-ethyl-l-dimethylphosphinylmethyleno～-benzene) and 1,1,3-tris(5-tert-butyl-4-dimethylphoa-phinylmethylenoxy-2-methyl-phenyl)butan.     

Reaction of Secondary Phosphine Oxides with Aromatic Aldehydes

Nucleophilic addition of secondary phosphine oxides to aromatic aldehydes proceeds under mild conditions (20-60°C, 10-40 h) and provides [bis(2-organylethyl)](arylhydroxymethyl)phosphine oxides in high yields.     

Pd-Catalysed Diastereoselective Synthesis of aza-Spirocyclic P-Stereogenic Phosphine Oxides

Phosphine oxides and spirocyclic compounds are privileged molecules widely employed in a variety of catalytic transformations either as chiral ligands for metals or bifunctional organocatalysts. Herein, we developed a Pd-catalysed cross-coupling reaction to synthesize spirocyclic amino-phosphine oxides with a P-stereogenic centre which could serve as potential P*(O), N-ligands or organocatalysis.     

Cobalt-Catalysed Reductive Etherification Using Phosphine Oxide Promoters under Hydroformylation Conditions

A phosphine-oxide-promoted, cobalt-catalysed reductive etherification using syngas as a reductant is reported. This novel methodology was successfully used to prepare a broad range of unsymmetrical ethers from various aldehydes and alcohols containing diverse functional groups, and was scaled-up to multigram scale under comparably mild conditions. Mechanistic experiments support an acetalization–hydrogenation sequence.     

Enantioselective Aldol Reactions Catalyzed by Chiral Phosphine Oxides

The development of enantioselective aldol reactions catalyzed by chiral phosphine oxides is described. The aldol reactions presented herein do not require the prior preparation of the masked enol ethers from carbonyl compounds as aldol donors. The reactions proceed through a trichlorosilyl enol ether intermediate, formed in situ from carbonyl compounds, which then acts as the aldol donor. Phosphine oxides activate the trichlorosilyl enol ethers to afford the aldol adducts with high stereoselectivities. This procedure was used to realize a directed cross‐aldol reaction between ketones and two types of double aldol reactions (a reaction at one/two α position(s) of a carbonyl group) with high diastereo‐ and enantioselectivities.     

P-手性膦氧化物的不对称催化合成研究进展

P-手性膦氧类化合物在药物化学、有机合成化学、生命及材料科学等领域具有重要的应用价值和潜能,是一类受到广泛关注的优势结构.近年来,针对这一结构的不对称催化构建取得了显著进展.本综述旨在从三级膦氧化物的去对称化反应和(动态)动力学拆分反应以及二级膦氧化物参与的不对称反应三种策略出发,介绍目前用于构建P-手性膦氧化物的不对称催化合成方法及最新研究进展.藉此也对这些反应的机理及其优势与不足之处进行简要讨论,为从事有机合成和有机膦化学相关的研究人员提供一些有益参考和借鉴.     

A Green Chemical Approach for Iodination of Pyrimidine Derivatives by Mechanical Grinding under Solvent-Free Conditions

The iodination of pyrimidines is usually carried out by using toxic reagents under acidic conditions, such as with sulfuric acid and nitric acid. To avoid toxic reagents, we developed a simple and eco-friendly approach for the iodination of pyrimidine derivatives under solvent-free conditions using solid iodine and AgNO₃ as an electrophilic iodinating reagent. The advantages of this method are the relatively short reaction time (20–30 min), simple set-up procedure, high yields (70–98%), and environmentally friendly reaction conditions. Our novel approach for the iodination of pyrimidines, as well as a variety of their derivatives, will contribute to the development of nucleobase-related drug candidates.     

Mild Reduction of Phosphine Oxides with Phosphites To Access Phosphines

A new method for the iodine‐catalyzed reduction of phosphine oxides with phosphites at room temperature is reported. The mild reaction conditions, scalability, and simple purification requirements render it a method of choice for the large‐scale production and facile regeneration of a variety of phosphines. Mechanistic studies, supported by DFT calculations of the oxygen transfer between the starting phosphine oxide and the phosphite reagent, are also presented. Such transmutations of phosphorus species were previously unknown.     

Coulombic Basis for Relative Hydrogen-Bonding Basicities and Conformational Energies of Tertiary Amine Oxides and Phosphine Oxides

The structures, energies, and natural atomic charges of 2-dimethylaminophenol oxide, 2-Me₂N-(O)C₆H₄OH, and 2-dimethylphosphinylphenol, 2-Me₂P(O)C₆H₄OH, in three different conformations were computed at the ab initio MP2/6-31G* level. Computed natural charges indicate distributions of electron density in amine oxides and phosphine oxides that are quite different from what is normally assumed on the basis of the formal charges in the usual representations of these compounds. The charges on nitrogen and phosphorus in these compounds are typically computed to be approximately zero on nitrogen and +2 on phosphorus, and the oxygen is considerably more negative in the phosphine oxide than in the amino oxide. Electronegativity differences thus play a larger role and formal charges a smaller one in determining atomic charges in these compounds than is generally believed. Despite the more negative oxygen in phosphine oxides, amine oxides are computed to be considerably more basic when participating in hydrogen bonding. Calculations treating the computed natural charges on these six conformations as point charges for classical approximations of the coulombic energies support the idea that the quantum mechanically computed relative energies are largely determined by coulombic interactions.     

Cerium(IV) Nitrate Complexes With Bidentate Phosphine Oxides

The reactions between ceric ammonium nitrate, (NH₄)₂Ce(NO₃)₆, (CAN) and the bidentate phosphine oxides, 4,5-bis(diphenylphosphine oxide)-9,9-dimethylxanthene (L¹), oxydi-2,1-phenylene bis(diphenylphosphine dioxide) (L²), 1,2-bis(diphenylphosphino)ethane dioxide (L³) and 1,4-bis(diphenylphosphino)butane dioxide, L⁴ have been investigated. The crystal structures of the molecular Ce(NO₃)₄L¹ ( 1 ), and ionic [Ce(NO₃)₃L³₂][NO₃]⋅CHCl₃ ( 3 ), [Ce(NO₃)₃L³₂][NO₃] ( 4 ) and the polymeric [Ce(NO₃)₃L⁴_1.5] [NO₃] ( 5 ) and the cerium(III) complex [Ce(NO₃)₂L¹₂][NO₃] ( 2 ) are reported. The thermal stability of the complexes has been examined by thermogravimetry with the gaseous decomposition products analysed by infrared spectroscopy. Evolution of CO₂ is found for both Ce(III) and Ce(IV) complexes with the later also forming NO₂. The formation of the complexes in solution has been studied by ³¹P NMR spectroscopy and further complexes [Ce(NO₃)₃L¹₂]⁺[NO₃]⁻ and [Ce(NO₃)₂L¹₃]²⁺2[NO₃]⁻ identified in CD₃CN solution. The complex ( 1 ) exists as a single molecular species in solution and is stable in dichloromethane whilst ( 3 ) decomposes on standing in both CD₂Cl₂ and CD₃CN to Ce(III) containing species. Complexes of L² have been identified by solution ³¹P NMR spectroscopy and these decompose in solution to give Ce(NO₃)₃L²₂. This study represents the first structural characterisations of Ce(IV) complexes with bidentate phosphine oxides.     

Brønsted Acid Promoted Reduction of Tertiary Phosphine Oxides

Recently, Brønsted acids, such as phosphoric acids, carboxylic acids, and triflic acid, were found to catalyze the reduction of phosphine oxides to the corresponding phosphines. In this study, we fully characterize the HCl, HOTf, and Me₂SiHOTf adducts of triphenylphosphine oxide and find that the thermally stable adduct Ph₃POH⁺OTf^– is efficiently converted into triphenylphosphine at 100 °C in the presence of readily available hydrosiloxanes. Under the same reaction conditions, also Ph₃POSiMe₂H⁺OTf^– selectively affords triphenylphosphine indicating that silylated phosphine oxides are likely intermediates in this process.     

Structures and Unexpected Dynamic Properties of Phosphine Oxides Adsorbed on Silica Surfaces

Solid‐state NMR spectroscopy of selected phosphine oxides adsorbed on silica surfaces establishes the surface mobilities, even of phosphine oxides with high melting points. Crystal structures of the adducts Ph₃PO ? HOSiPh₃ and Cy₃PO ? H₂O indicate that the interactions with silica involve hydrogen bonding of the P?O group to adsorbed water and surface silanol groups.     

The Reactivity of Cyameluric Chloride C6N7Cl3 towards Phosphines and Phosphine Oxides

Organophosphines (R₂PH) and phosphineoxides (R₂OPH) show a very high reactivity towards cyameluric chloride C₆N₇Cl₃. For example, 2,4,6‐trisdiphenylphosphino‐tri‐s‐triazine ( 1 ) forms quantitatively within a few seconds. Tris‐diphenylphosphinsulfide‐s‐heptazine ( 2 ) was obtained by reaction of 1 with sulfur. These compounds represent a new class of s‐heptazine derivatives which tend, unlike their s‐triazine analogues, to decompose in solution. 1 forms crystals with nitromethane, which were analysed by single‐crystal X‐ray diffraction. The nitromethane molecules fill the gaps in the crystal lattice supported by hydrogen bonds, C–H ··· π ring, and N–O ··· π ring interactions. All compounds were characterized by ¹H, ¹³C and ³¹P NMR and vibrational (FT‐IR, Raman) spectroscopy. The thermal stability of selected derivatives was measured by TG, indicating surprisingly low thermal decomposition temperatures.     

β-溴代萘的化学除氧环糊精诱导室温燐光法测定

本文首次成功地建立了以KI或Tl_2SO_4无机盐作重原子,Na_2SO_3作除氧剂,测定β-溴代萘的化学除氧环糊精诱导室温燐光法。该方法比以往用卤代烷烃作重原子吹氮除氧CD-RTP法操作简便。本文详细研究了化学除氧的各种影响条件及方法的适用性。实验表明,以K1作重原子的体系比TI_2SO_4体系有更高的灵敏度和更宽的条件宽容度,而且操作更为简便。目前此种方法还仅适用于含内重原子化合物的测定。