Asymmetric Cyclopropanation of Optically Active Vinyl Sulfoxides: A New Synthetic Approach to Biologically Active Compounds

Abstract

The influence of adjacent substituents on stereochemical course of cyclopropanation of vinyl sulfoxides with stabilized and nonstabilized ylides, as well as dependence on reaction conditions, was investigated. Application of optically active cyclopropanes obtained in the synthesis of conformationally constrained analogs of L-glutamic acid, the useful pharmacological tools in investigation of excitatory amino acid receptors, is presented.     

Quantum Chemical Study of the Addition of Secondary Phosphine Chalcogenides to Vinyl Selenides

Russian Journal of Organic Chemistry - DFT quantum chemical calculations at the B3PW91/6-31G(d) level of theory have shown that the addition of secondary phosphine sulfides and phosphine selenides...     

Unexpected Reaction of Secondary Phosphine Chalcogenides with Acridine

Secondary phosphine chalcogenides reacted with acridine under mild conditions according to the nucleophilic addition scheme to form 9-chalcogenophosphoryl-9,10-dihydroacridines.

     

Unusual Course of the Reaction of Allyl Phosphine Oxides with the Grundmann Ketone

This article describes efficient preparation of isomeric allyl phosphine oxides possessing a protected cyclohexanediol fragment. Their base-catalyzed interconversions are examined and reactions with the Grundmann ketone provide an adduct containing the rearranged vinyl phosphine oxide moiety, instead of 19-norvitamin D₃ analogs, the expected products of the Horner–Wittig process.     

Atom-Economic Synthesis of Tris[2-(organylthio)ethyl]phosphine Oxides from Phosphine and Vinyl Sulfides

Abstract

Phosphine, generated from elemental phosphorus in the system KOH-toluene-H₂O, reacts with vinyl sulfides under free radical conditions (AIBN, dioxane, 65–70°C, atmospheric pressure) to form regiospecifically tris[2-(organylthio)ethyl]phosphines, which are readily oxidized in air to corresponding tris[2-(organylthio)ethyl]phosphine oxides.     

Three-Component Reaction of 4-Methylpyridine with Alkyl Propiolates and Secondary Phosphine Chalcogenides

The reaction between 4-methylpyridine, alkyl propiolates, and secondary phosphine oxides proceeded as N-vinylation-C-phosphorylation with stereo- and regioselective formation of (E)-N-ethenyl-C²- phosphoryl-1,2-dihydropyridines [when using bis(2-phenylethyl)phosphine oxide] or (E)-N-ethenyl-C⁴- phosphoryl-1,4-dihydropyridines (when using diphenylphosphine oxide). The process occurred at 60–62°C within 3 h to give functional dihydropyridines in 40–82% yield. Under similar conditions, bis(2-phenylethyl) phosphine sulfide and selenide reacted with alkyl propiolates preferably by nucleophilic PH-monoaddition at the triple bond.     

(OXO)(Phosphine)Ruthenium(IV) Complexes: Oxygen Atom Transfer in the Oxidation of Olefins,Sulfides, Sulfoxides,and Free Phosphines

Kinetic and mechanistic studies of the oxidation of olefins, sulfides, and sulfoxides by [Ru^IV(bpy)₂(O)- (PR₃)](ClO₄)₂ (bpy = 2,2′-bipyridine; R = ethyl or phenyl) complexes have been conducted in both methylene chloride and acetonitrile. In all cases, the rate law shows a first-order dependence on both the concentration of (oxo)ruthenium(IV) species and the target substrate. In addition, product distributions of substrate oxidation exhibit a strong dependence on both the particular phosphine ligand and the solvent utilized in the experiment. On the basis of labelling experimcnts and kinetic evidence, a mechanism is proposed involving a two-electron, oxygen atom insertion into the target substrate. Notably, an (oxidized substrate)ruthenium(II) complex has been isolated and characterized for the oxidation of styrene by the (oxo)(triethylphosphine)ruthenium(IV) complex, where a cyclic voltammogram of this complex displays one quasi-reversible Ru(III)/Ru(II) couple with an E_1/2 = 1.24 V vs SSCE. Kinetic analysis of styrene oxidation indicates that the formation of benzaldehyde from styrene does not occur simply by two sequential two-electron steps. In this regard, alternative mechanisms are discussed.     

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.     

Preparations of Saturated N‐P‐N Type Secondary Phosphine Oxides and their Applications in Cross‐Coupling Reactions

A series of cyclohexane‐1,2‐diamine ( 3a – 3d ) and benzene‐1,2‐diamine derivatives ( 3e – 3h ) were pre‐ pared. Followed by hydrolysis, the reaction of 3a – 3c with PCl₃ successfully led to the formation of cor‐ responding metastable saturated heteroatom‐substituted secondary phosphine oxides (HASPO 4a – 4c ), a tautomer of the saturated heteroatom‐substituted phosphinous acid (HAPA). Whereas ambient‐stable diamine‐coordinated palladium complexes were obtained, HAPA‐coordinated palladium complexes were not successfully synthesized. The molecular structures of HASPO 4c , Pd(OAc)₂(3a) , PdBr₂(3b) and Pd(OAc)₂(3c) and [Cu(NO₃)(3d)⁺][NO₃ ^? ] were determined by single‐crystal X‐ray diffraction method. Catalysis of in‐situ Suzuki‐Miyaura cross‐coupling reactions for aryl bromides and phenylboronic acid using diamine 3a as ancillary ligand showed that the optimized reaction condition at 60 °C is the combination of 2 mmol % 3a /3.0 mmol KOH/1.0 mL 1,4‐dioxane/1 mmol % Pd(OAc)₂. Moreover, moderate reactivity was observed when using aryl chlorides as substrates (supporting infor‐ mation). When diamine 3d was employed in Heck reaction, good tolerance of functional groups of aryl bromides were observed while using 4‐bromoanisole and styrene as substrates. The optimized condi‐ tion for Heck reaction at 100 °C is 3 mmol % 3d /3.0 mmol CsF/1.0 mL toluene/3 mmol % Pd(OAc)₂. In general, cyclohexane‐1,2‐diamine derivatives exhibited better catalytic properties than those of benzene‐1,2‐diamines.     

Phosphorylation of Acetylaminophenols with Secondary Phosphine Chalcogenides: Synthesis of O-(Acetylamino)phenyl Chalcogenophosphinates

Russian Journal of General Chemistry - Oxidative cross-coupling of 4-acetylaminophenol (paracetamol) and its structural isomers (2- and 3-acetylaminophenols) with secondary phosphine chalcogenides...     

Synthesis of Tetraarylethene Luminogens by C−H Vinylation of Aromatic Compounds with Triazenes

Tetraarylethenes are obtained by acid‐induced coupling of vinyl triazenes with aromatic compounds. This new C?H activation route for the synthesis of aggregation‐induced emission luminogens is simple, fast, and versatile. It allows the direct grafting of triarylethenyl groups onto a variety of aromatic compounds, including heterocycles, supramolecular hosts, biologically relevant molecules, and commercial polymers.     

Synthesis and Characterization of New N-(Diphenylphosphino)-Naphthylamine Chalcogenides: X-Ray Structures of (1-NHC10H7)P(Se)Ph2 and Ph2P(S)OP(S)Ph2

Abstract

The reaction of 1-naphthylamine with one equivalent of chlorodiphenylphosphine in the presence of triethylamine gave the (1-NHC₁₀H₇)PPh₂ (1) ligand. Refluxing of 1 with elemental sulfur or grey selenium in toluene (1:1 molar ratio) afforded (1-NHC₁₀H₇)P(S)Ph₂ (2) and (1-NHC₁₀H₇)P(Se)Ph₂ (3), respectively. Moreover, the byproduct {Ph₂P(S)}₂O (4) was isolated from the reaction of 1 with elemental sulfur. Compounds 1–3 were identified and characterized by multinuclear (¹H, ¹³C, ³¹P, ⁷⁷Se) NMR spectroscopy, mass spectrometry, and elemental analysis. Crystal structure determinations of 3 and 4 were carried out.     

Mild and Efficient Deoxygenation of Sulfoxides with MoCl5/Indium System

It has been demonstrated that dialkyl, diaryl, and aryl alkyl sulfoxides can be efficiently converted into the corresponding sulfides by the reaction with a MoCl₅/In system in good to excellent yields under mild conditions.     

Reactions of Bis(Trifluoromethyl)Phosphine and Tetrakis(Trifluoromethyl)Phosphine with Ruthenium Carbonyl Clusters

Abstract

The reaction of (CF₃)₂P-P(CF₃)₂ with [Ru₃(CO)₁₂] yielded compounds : [Ru₁₄(CO)₁₃{μ-P(CF₃)₂)₂] (1), [Ru₄(CO)₁₄{μ-P(CF₃)₂}₂] (2), and [Ru₄(CO)₁₁{μ-P(CF₃)₂}₄] (3); reaction with [μ-H)₄Ru₄(CO)₁₂] yielded (1) and [(μ-H)₃Ru₄(CO)₁₂{μ-P(CF₃)₂}] (4). The reaction of (CF₃)₂PH with [Ru₃(CO)₁₂] yielded compounds (1) and (4) and compounds (1) and (2) using cluster : ligand ratios of 1:1 and 1:2 respectively. All the compounds have been characterised by X-ray crystallography; a schematic diagram of their structures is shown in Figure 1. The fluxional behaviour of the hydrides in (4) was studied using variable temperature ¹H NMR spectroscopy (see Figure 2). The result of this study was used in the assignment of hydride positions of (4) in the solid state.     

多功能手性膦催化活泼烯烃的不对称分子间Rauhut-Currier反应

研究实现了多功能手性膦催化的3-芳酰基丙烯酸酯和烯酮的不对称分子间Rauhut-Currier反应,为多羰基手性化合物的构建提供了一种新方法.在使用（S,R_S）-X8作为催化剂和甲苯作为溶剂的条件下,一系列含有不同取代基团的3-芳酰基丙烯酸酯和烯酮均可顺利地发生不对称Rauhut-Currier反应,从而高产率且高对映选择性地生成相应的产物.对照实验表明多功能手性膦催化剂中的N-H键对反应的对映选择性的控制起到了至关重要的作用;膦谱监测实验结果表明手性膦催化剂对烯酮的Michael加成是该反应的启动步骤.     

Vinyl sulfoxides as stereochemical controllers in intermolecular Pauson-Khand reactions: applications to the enantioselective synthesis of natural cyclopentanoids

The use of sulfoxides as chiral auxiliaries in asymmetric intermolecular Pauson-Khand reactions is described. After screening a wide variety of substituents on the sulfur atom in alpha,beta-unsaturated sulfoxides, the readily available o-(N,N-dimethylamino)phenyl vinyl sulfoxide (1 i) has proved to be highly reactive with substituted terminal alkynes under N-oxide-promoted conditions (CH3CN, 0 degrees C). In addition, these Pauson-Khand reactions occurred with complete regioselectivity and very high diastereoselectivity (de=86->96 %, (S,R(S)) diastereomer). Experimental studies suggest that the high reactivity exhibited by the vinyl sulfoxide 1 i relies on the ability of the amine group to act as a soft ligand on the alkyne dicobalt complex prior to the generation of the cobaltacycle intermediate. On the other hand, both theoretical and experimental studies show that the high stereoselectivity of the process is due to the easy thermodynamic epimerization at the C5 center in the resulting 5-sulfinyl-2-cyclopentenone adducts. When it is taken into account that the known asymmetric intermolecular Pauson-Khand reactions are limited to the use of highly reactive bicyclic alkenes, mainly norbornene and norbornadiene, this novel procedure constitutes the first asymmetric version with unstrained acyclic alkenes. As a demonstration of the synthetic interest of this sulfoxide-based methodology in the enantioselective preparation of stereochemically complex cyclopentanoids, we have developed very short and efficient syntheses of the antibiotic (-)-pentenomycin I and the (-)-aminocyclopentitol moiety of a hopane triterpenoid.     

Mild and Efficient Deoxygenation of Sulfoxides with a WCl6/Indium System

Dialkyl, diaryl, and aryl alkyl sulfoxides can be rapidly converted to the corresponding sulfides with a WCl₆/In system in excellent yields under mild conditions.     

Mechanism of Phosphine Borane Deprotection with Amines: The Effects of Phosphine,Solvent and Amine on Rate and Efficiency

The kinetics of borane transfer from simple tertiary phosphine borane adducts to a wide range of amines have been determined. All data obtained, including second‐order kinetics, lack of cross‐over, and negative entropies of activation for reaction of triphenylphosphine borane with quinuclidine and triethylamine, are consistent with a direct (S_N2‐like) transfer process, rather than a dissociative (S_N1‐like) process. The identities of the amine, phosphine, and solvent all impact substantially on the rate (k) and equilibrium (K) of the transfer, which in some cases vary by many orders of magnitude. P‐to‐N transfer is more efficient with cyclic amines in apolar solvents due to reduced entropic costs and ground‐state destabilisation. Taken as a whole, the data allow informed optimisation of the deprotection step from the stand‐point of rate, or synthetic convenience. In all cases, both reactants should be present at high initial concentration to gain kinetic benefit from the bimolecularity of the process. Ultimately, the choice of amine is dictated by the identity of the phosphine borane complex. Aryl‐rich phosphine boranes are sufficiently reactive to allow use of diethylamine or pyrrolidine as a volatile low polarity solvent and reactant, whereas more alkyl‐rich phosphines benefit from the use of more reactive amines, such as 1,4‐diaza[2.2.2]bicyclooctane (DABCO), in apolar solvents at higher temperatures.     

Interaction of Tris(3-Hydroxymethyl)Phosphine with Cinnamic Acids

Abstract

Phosphonium zwitterions of the known type R₃P⁺CH(Ar)CH₂CO₂ ^? (II) are obtained as a racemic mixture in moderate yield via a 1:1 reaction of cinnamic acids (Ar = phenyl, or substituted phenyl) with [HO(CH₂)₃]₃P in acetone at room temperature under Ar. The products are characterized by elemental analysis, ³¹P{¹H}-, ¹H-, and ¹³C{¹H}-NMR spectroscopies, and mass spectrometry, although they contain a minor coproduct formed via neutralization of the positive and negative charges of II with the respective acid and phosphine reactants (see Experimental Section). In CD₃OD, the monodeuterated salts R₃P⁺CH(Ar)CH(D)CO₂ ^? are formed as a mixture of diastereomers with d.r. values of ～2 to 8, depending on substituent groups present in the organic acid; in these studies, 2-HO-cinnamic acid is the most reactive, and β-methylcinnamic acid is the least reactive.     

Reaction of hydroxyflavones with secondary phosphine chalcogenides in the CCl4/Et3N system: synthesis of a new family of phosphorylated flavonoids

Flavonoids (3-hydroxy-, 3-hydroxy-4′-methoxy-, 3-hydroxy-7-methoxy-, and 5,7-dihydroxyflavones) react with secondary phosphine chalcogenides in the CCl₄/Et₃N redox system (50–52 °C, 3–5 h) to afford chemoselectively the corresponding chalcogenophosphinates of the hydroxyflavones in 65–82% yield.