硝酸铁催化氧化二芳基乙醇酮制备二芳基乙二酮

用AcOH作溶剂,PEG400做相转移催化剂,硝酸铁能将二芳基乙醇酮催化氧化为二芳基乙二酮。产物结构用IR,MS和1H NMR光谱对其进行了表征。该方法有反应时间短,产率较高,操作简便等优点,是一种有效的由二芳基乙醇酮氧化制备二芳基乙二酮的方法。     

N-Cyanomethyl-β-chloroamines: a convenient source of aziridinium ions

N-Cyanomethyl-β-chloroamines smoothly react with a range of alcohols or amines to give regio- and stereoselectively 1,2-aminoethers or 1,2-diamines. The reaction proceeds through the formation of an intermediate aziridinium ion. The N-cyanomethyl group can then be cleaved easily.     

Fluoroalkene chemistry: Part 2. Reactions of thiols with some toxic 1,2-dichlorinated polyfluorocycloalkenes

1,2-Dichlorotetrafluorocyclobutene, 1,2-dichlorohexafluorocyclopentene and 1,2-dichlorooctafluorocyclohexene were treated with an equimolar amount of benzenethiol, 2-methoxybenzenethiol, 3-methoxybenzenethiol and 4-methoxybenzenethiol in acetonitrile with potassium carbonate. Each combination of fluoroalkene and thiol gave a mixture of mono and bis vinyl substitution products whose proportions depended on the ring size of the fluorocycloalkene and the size and electronic characteristics of the thiol. Treatment of 1,2-dichlorotetrafluorocyclobutene with one or two molar equivalents of N-acetylcysteine isopropyl ester in acetonitrile with potassium carbonate produced the mono and bis vinyl substitution products accordingly. The results support the contention that the high inhalation toxicity of the fluorocycloalkenes is due to reaction with two molar equivalents of biological thiols in the lung.     

Sonogashira cross-coupling of 3-bromo-1,2-diones: an access to 3-alkynyl-1,2-diones

A new general method for the synthesis of enols of cyclic 3-alkynyl-substituted 1,2-diketones is developed. Sonogashira cross-coupling of silyl enolates of cyclic 3-bromo-cyclopentane- and 3-bromo-cyclohexane-1,2-diones with variety of substituted acetylenes afforded enols of cyclic 3-alkynyl-1,2-diones with good yields (up to 93%) in a short reaction time. The starting 3-bromo-1,2-diones are easily obtainable by direct bromination of 1,2-diones with NBS.     

Straightforward Synthesis of 1,2-Amino Phosphate Diesters and Application to the Synthesis of Novel 1,2-Amino Ether Diesters

A variety of 1,2-amino alcohol diesters 1 reacted smoothly with diethyl chlorophosphate under basic conditions to afford the corresponding 1,2-amino phosphate diesters 2 in excellent yields. These compounds served as useful precursors for subsequent nucleophilic attack by alcohols in an S_N2 fashion to provide 1,2-amino ether diesters 3.     

Methyltrioxorhenium catalyzed oxidation of 1,2-diols to 1,2-diketones using hydrogen peroxide as oxidant

A variety of 1,2-diols were oxidized selectively to the corresponding 1,2-diketones by the dropwise addition of 30% aqueous hydrogen peroxide using methyltrioxorhenium as catalyst.     

Heterogeneous platinum catalytic aerobic oxidation of cyclopentane-1,2-diols to cyclopentane-1,2-diones

A method for the aerobic oxidation of cyclopentane-1,2-diols to the corresponding diketones over a commercial heterogeneous Pt/C catalyst is described. Unsubstituted and 3- or 4-substituted cyclopentane-1,2-diols are oxidized to 1,2-dicarbonyl compounds in good yields under the reported optimized reaction conditions (atmospheric air, 1 mol % of catalyst, 1 equiv of LiOH, aqueous solvents and 60 °C temperature). The method is applicable for producing cyclopentane-1,2-diketones in a scalable manner.     

Novel 3-Cyanosubstituted 1,2-Thiaphosphacyclanes: Synthesis and Stereochemistry

The facile synthetic route to 5- and 6-membered 3-cyano-2-oxo-1,2-thiaphosphacyclanes and 6-cyano-2-oxa-10-oxa(thia)-phosphabicyclo [4.4.0]-decane-1-oxides was elaborated via intramolecular S-alkylation in a series of y -haloalkylsubstituted thiophosphorylacetonitriles. The compounds were used to prepare novel P(III)-containing bidentate ligands with definite stereochemistry. Diastereomeric transformations among 2-oxo-1,2-thiaphosphinanes were found and the mechanism of such transformations is suggested.     

Intramolecular P=S and P=N Alkylation. General Method for Synthesizing 1,2-Heteraphosphacyclanes

Results have been generalized for investigations on the synthesis of 1,2-thiaphosphacyclanes by intramolecular P=S alkylation of -haloalkyl substituted compounds of four-coordinated phosphorus with a P=S bond. The method has been extended to nitrogen-containing analogs with a P=N bond. A new general method is proposed for the synthesis of 1,2-thia- and 1,2-azaphosphacyclanes.     

Photochromic dihetarylethenes. 10. Photochromic 1,2-bis[2-(benzothiazol-2-yl)-3-thienyl]- and 1,2-bis[2-(benzothiazol-2-yl)benzothiophen-3-yl]ethenes

Dithienylethenes containing the thiophene rings with benzothiazolyl substituents in position 2 were synthesized. 1,2-Bis[2-(benzothiazol-2-yl)benzothiophen-3-yl]hexafluorocyclopentene and 1,2-bis[2,5-di(benzothiazol-2-yl)-3-thienyl]hexafluorocyclopentene possess photochromic properties. The open forms of 1,2-bis(2-benzothiazolylhetaryl)ethenes fluoresce, but introduction of the benzothiazole rings into dihetarylethenes significantly lowers the fatigue resistance of photochromes and favors thermal reversibility.     

Facile Preparation of 1,2-Diketones

Easily accessible lead-like libraries of heterocyclic molecules useful for high-throughput screening are of continuous interest to the pharmaceutical industry. A number of drug-like libraries are derived from aromatic 1,2-diketones; however, nonsymmetrical 1,2-diketones are challenging to prepare. This communication describes a simple and practical synthesis of 1,2-diketones based on a controlled cross benzoin-like condensation reaction.     

Controlled radical polymerization of styrene in the presence of cyclic 1,2‐disulfides

The thermal polymerization of styrene (St) in the presence of cyclic 1,2‐disulfides at 120 °C was investigated. In the polymerization of St in the presence of 1,2‐dithiane (DT), that is, six‐member cyclic 1,2‐disulfide, the polymer yields and molecular weights increased with the reaction time. The linear relation between the polymer yields and molecular weights was observed, and the line passed through an original point. The molecular weight distributions of the polymers remained almost constant but were not narrow. For this polymerization with a living nature, we proposed the following mechanism: the propagating St radical reacted with thiyl radicals derived from DT, leading to the formation of dormant species, and the formed C S bond of the dormant was dissociated again to give the propagating polystyryl radical and thiyl radical. Similar results were obtained in the thermal polymerization of St at 120 °C in the presence of 1,2‐dithiacycloheptane, that is, seven‐member cyclic 1,2‐disulfide. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 145–151, 2001     

<Emphasis Type="Italic">Ab initio</Emphasis> quantum-chemical calculations of the energies and structures of 1,2-acetylenedithiol isomers

Ab initio quantum-chemical calculations of 1,2-acetylenedithiol isomers were carried out. The MP2(full), DFT(B3PW91, MPW1PW91), G3, G3B3, and CBS-Q methods were used. According to the calculations, the most stable isomers were 1,2-dithiet, thiiranethione, and trans-1,2-dithioglyoxal. The necessity of including basis set functions with a large angular momentum in calculations was confirmed. The relatively high stability of 1,2-dithiet was attributed to the aromaticity of its four-membered ring. It was noted that the carbon-carbon bond in the three-membered rings of the cis- and trans-isomers of thiirenethiols was unusually short.     

Efficient Synthesis of Quinoxalines in the Ionic Liquid 1-n-Butylimidazolium Tetrafluoroborate ([Hbim]BF4) at Ambient Temperature

Quinoxaline derivatives have been synthesized in excellent yields using an ionic liquid (IL) (viz., 1-n-butylimidazolium tetrafluoroborate) as a reaction medium as well as promoter from various 1,2-diketones and aryl-1,2-diamines. The process is general for the synthesis of quinoxaline derivatives from aromatic as well as aliphatic-1,2-diketones. The advantages of the present method are ambient reaction temperature, simplicity of operation, high yields of products, the recyclability of the IL, and ecofriendly nature of the reaction medium.     

Keggin type heteropolyacids-catalyzed synthesis of quinoxaline derivatives in water

Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water.This method provides a new and efficient protocol in terms of small quantity of catalyst,a wide scope of substrates,and simple work-up procedure.     

Preparation of an aliphatic-substituted hypervalent iodine compound, tetracoordinate 1,2-iodoxetane 1-oxide, and its application to oxidation

A tetracoordinate 1,2-iodoxetane was prepared by the fluorination of a tricoordinate 1,2-iodoxetane with xenon difluoride followed by hydrolysis. The tetracoordinate 1,2-iodoxetane oxidized alcohols and a sulfide to the corresponding aldehydes and ketones, and a sulfoxide, respectively, in good to moderate yields under mild conditions.     

Fe3O4@SiO2/Schiff base complex of metal ions as an efficient and recyclable nanocatalyst for the green synthesis of quinoxaline derivatives

Fe₃O₄@SiO₂/Schiff base complex of metal ions catalyzed the reaction between phenylene-1,2-diamines and 1,2-diketones to produce quinoxalines in aqueous media at room temperature. This eco-friendly method provides several advantages such as mild reaction conditions, good to excellent yields, simple work-up, and nanocatalyst stability. Also, nanocatalyst can be simply recovered by a magnetic field and reused for at least five successive reactions.     

Synthesis of 1,2-Azaphosphacyclanes; Generality of the Mechanism of P=N Alkylation and Arbuzov Reaction

A novel convenient "one-pot" synthesis of 2-oxo-1,2 u 5 -azaphosphacyclanes 1 and 1,2 u 4 -azaphosphacyclanium salts 2 via intramolecular N-alkylation of y -halogenalkyl-substituted iminophosphoryl compounds 3 has been developed. The common nature of the reaction of intramolecular cyclization of iminophosphoryl compounds having an alkoxy group at the phosphorus atom and the Arbuzov reaction has been established.     

Koordinationseigenschaften von Carbaboranylchlorophosphanen: Synthese und Molekülstruktur von cis-rac-Molybdäntetracarbonyl{1,2-bis(chlorophenylphosphino)-1,2-dicarba-closo-dodecaboran(12)}

Coordination Properties of Carbaboranylchlorophosphines: Synthesis and Molecular Structure of cis-rac -Molybdenumtetracarbonyl{1,2-bis(chlorophenylphosphino)-1,2-dicarba-closo-dodecaborane(12)} Rac-1,2-bis(chlorophenylphosphino)-1,2-dicarba-closo-dodecaborane(12) ( 1 ) reacts with [Mo(CO)₄(NBD)] (NBD = norbornadiene) after several hours at 50–55 °C to yield cis-rac-[Mo(CO)₄{1,2-(PPhCl)₂C₂B₁₀H₁₀}] ( 2 ). 2 was characterised spectroscopically (¹H, ¹³C, ¹¹B and ³¹P NMR) and by crystal structure determination.     

1,2-Bis(dimethylamino)-3,4,5-triphenyl-3,4,5-triphospha-1,2-diborolan und 1,2-Bis(dimethylamino)-3,4,5,6-tetra-tbutyl-3,4,5,6-tetraphospha-1,2-diborin: Synthese und Struktur sowie Berechnungen zur Molekülstruktur

1,2-Bis(dimethylamino)-3,4,5-triphenyl-3,4,5-triphospha-1,2-diborolane and 1,2-Bis(dimethylamino)-3,4,5,6-tetra-tbutyl-3,4,5,6-tetraphospha-1,2-diborine: Synthesis and Structure as well as Calculations on the Molecular Structure The diphosphides K₂[(C₆H₅)P? (C₆H₅)P? P(C₆H₅)], 4 or K₂[(tBuP)? (tBuP)₂? P(tBu)], 5 , react with (ClBNMe₂)₂ to form the binary 5-membered ring system 1,2-bis(dimethylamino)-3,4,5-triphenyl-3,4,5-triphospha-1,2-diborolane (C₆H₅P)₃(BNMe₂)₂, 2a , and the 6-membered ring system 1,2-bis(dimethylamino)-3,4,5,6-tetra-tbutyl-3,4,5,6-tetraphospha-1,2-diborine, (tBuP)₄(BNMe₂)₂, 3a , respectively. 2a and 3a could be obtained in a pure form and characterized NMR spectroscopically and by X-ray structure analyses. The two ring systems are folded; 2a exists in the ?envelope”?- 3a in the ?boat”?-conformation. Ab initio computations for 3,4,5-triphospha-1,2-diborolane M5 show that the global minimum is characterized by one B? P double bond. The parent compound geometry M6 is characterized by transannular bonding in the PH? BH? BH? PH moiety which differs in character from those in the four- and five-membered rings (BH)₂(PH)₂ and (BH)₂(PH)₃ M5 d , respectively. Explicit calculation of the influence of amino substituents on boron improved agreement of the bond length between computed and X-ray data.