A Study on the Regioselectivity of the Cyclization Reaction of 5－Amino－1， 2， 4－triazole with Asym－l， 3－dicarbonyl Compound

ＡＳｔｕｄｙｏｎｔｈｅＲｅｇｉｏｓｅｌｅｃｔｉｖｉｔｙｏｆｔｈｅＣｙｃｌｉｚａｔｉｏｎＲｅａｃｔｉｏｎｏｆ５－Ａｍｉｎｏ－１，２，４－ｔｒｉａｚｏｌｅｗｉｔｈＡｓｙｍ－ｌ，３－ｄｉｃａｒｂｏｎｙｌＣｏｍｐｏｕｎｄ￥ＲｏｎｇＪｉａｎＬＵ；ＧａｏＦｅｎｇ...     

Permselectivity of 4－Aminophenol，Paracetanol and Phenacetin on the Self－Assembled n－Alkanethiol Monolayer Modified Gold Electrode

Ｐｅｒｍｓｅｌｅｃｔｉｖｉｔｙｏｆ４－Ａｍｉｎｏｐｈｅｎｏｌ，ＰａｒａｃｅｔａｎｏｌａｎｄＰｈｅｎａｃｅｔｉｎｏｎｔｈｅＳｅｌｆ－Ａｓｓｅｍｂｌｅｄｎ－ＡｌｋａｎｅｔｈｉｏｌＭｏｎｏｌａｙｅｒＭｏｄｉｆｉｅｄＧｏｌｄＥｌｅｃｔｒｏｄｅＬｉＪｉｎｇ－ｈ...     

Simultaneous Spectrophotometric Determination of Trace Palladium and Rhodium with2，4－TADAT

ＳｉｍｕｌｔａｎｅｏｕｓＳｐｅｃｔｒｏｐｈｏｔｏｍｅｔｒｉｃＤｅｔｅｒｍｉｎａｔｉｏｎｏｆＴｒａｃｅＰａｌｌａｄｉｕｍａｎｄＲｈｏｄｉｕｍｗｉｔｈ２,４－ＴＡＤＡＴＺＨＡＮＧＸｉａｏ－ｌｉｎｇ;ａｎｄＺＨＡＮＧＧｕａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈ...     

Catalytic Oxidative Dehydrogenation of Isobutane over KF-Zn_3(PO_4)_2

ＩｎｔｒｏｄｕｃｔｉｏｎＡｌｔｈｏｕｇｈｔｈｅｃａｔａｌｙｔｉｃｄｅｈｙｄｒｏｇｅｎａｔｉｏｎｏｆｉｓｏｂｕｔａｎｅｉｎｔｏｉｓｏｂｕｔｅｎｅｈａｓｂｅｅｎｃａｒｒｉｅｄｏｕｔｉｎｃｏｍｍｅｒｃｉａｌｐｌａｎｔｓｏｖｅｒＣｒ２Ｏ３－Ａｌ２Ｏ３ｏｒｎｏ...     

Study of Catalysts Based on High Surface Area MnO_2 for Catalytic Combustion of CH_4

ＳｔｕｄｙｏｆＣａｔａｌｙｓｔｓＢａｓｅｄｏｎＨｉｇｈＳｕｒｆａｃｅＡｒｅａＭｎＯ２ｆｏｒＣａｔａｌｙｔｉｃＣｏｍｂｕｓｔｉｏｎｏｆＣＨ４ＷＡＮＧＸｉａｎｇＸＩＥＹｏｕｃｈａｎｇ１）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙＰｅｋｉｎｇＵｎｉｖｅｒ...     

The Division of Analytical Chemistry of The Federation of European Chemical Societies

ＦＥＣＳ ,ｔｈｅＦｅｄｅｒａｔｉｏｎｏｆＥｕｒｏｐｅａｎＣｈｅｍｉｃａｌＳｏｃｉ ｅｔｉｅｓ,ｃｏｍｐｒｉｓｅｓａｎｕｍｂｅｒｏｆＤｉｖｉｓｉｏｎｓａｎｄＷｏｒｋｉｎｇＰａｒ ｔｉｅｓｓｐｅｃｉａｌｉｚｉｎｇｉｎｃｅｒｔａｉｎｆｉｅｌｄｓｓｕｃｈａｓＦｏｏｄＣｈｅｍ ｉｓｔｒｙ ,ＥｌｅｃｔｒｏｃｈｅｍｉｓｔｒｙｏｒＣｈｅｍｉｃａｌＥｄｕｃａｔｉｏｎ .ＡｍｏｎｇｔｈｅｍｔｈｅＤｉｖｉｓｉｏｎｏｆＡｎａｌｙｔｉｃａｌＣｈｅｍｉｓｔｒｙ ,ＤＡＣ ,ｉｓｏｎｅｏｆｔｈｅｌａｒｇｅｓｔｗｉｔｈｒｅｓｐｅｃｔｔｏ…     

Syntheses and Characterization of Metal Complexes of L－Lysine－N，N，N＇，N＇－tetraacetic Acid and L－Lysine－N，N，N＇，N＇－tetramethylenepho sphonic Acid

ＳｙｎｔｈｅｓｅｓａｎｄＣｈａｒａｃｔｅｒｉｚａｔｉｏｎｏｆＭｅｔａｌＣｏｍｐｌｅｘｅｓＯｆＬ－Ｌｙｓｉｎｅ－Ｎ,Ｎ,Ｎ＇,Ｎ＇－ｔｅｔｒａａｃｅｔｉｃＡｃｉｄａｎｄＬ－Ｌｙｓｉｎｅ－Ｎ,Ｎ,Ｎ＇,Ｎ＇－ｔｅｔｒａｍｅｔｈｙｌｅｎｅｐｈＯｓｐｈｏｎｉ...     

The Synthesis and Biological Activity of N－Arylamino Carbonyl Methylene 1，2－Benzothiazine 1，1－Dioxides

ＴｈｅＳｙｎｔｈｅｓｉｓａｎｄＢｉｏｌｏｇｉｃａｌＡｃｔｉｖｉｔｙｏｆＮ－ＡｒｙｌａｍｉｎｏＣａｒｂｏｎｙｌＭｅｔｈｙｌｅｎｅ１，２－Ｂｅｎｚｏｔｈｉａｚｉｎｅ１，１－Ｄｉｏｘｉｄｅｓ￥ＧｕｏＦｅｎｇＺＨＡＯ；ＨｕａＺｈｅｎｇＹＡＮＧ（Ｉｎｓｔｉｔｕ...     

A FACILE SYNTHESIS OF CHIRAL 3－ALKYL－3， 4－DIHYDRO－2H－1， 4－BENZOXAZINE DERIVATIVES

ＡＦＡＣＩＬＥＳＹＮＴＨＥＳＩＳＯＦＣＨＩＲＡＬ３－ＡＬＫＹＬ－３，４－ＤＩＨＹＤＲＯ－２Ｈ－１，４－ＢＥＮＺＯＸＡＺＩＮＥＤＥＲＩＶＡＴＩＶＥＳ￥ＬｕｎＪｉａＸＩＥ（ＮａｔｉｏｎａｌｉｎｓｔｉｔｕｔｅｏｆＰｈａｒｍａｃｅｕｔｉｃａｌＲｅｓｅａｒｃｈ...     

Voltammmetric Determination of Uric Acid in the Presence of Ascorbates Using Overoxidized Polypyrrol

ＶｏｌｔａｍｍｍｅｔｒｉｃＤｅｔｅｒｍｉｎａｔｉｏｎｏｆＵｒｉｃＡｃｉｄｉｎｔｈｅＰｒｅｓｅｎｃｅｏｆＡｓｃｏｒｂａｔｅｓＵｓｉｎｇＯｖｅｒｏｘｉｄｉｚｅｄＰｏｌｙｐｙｒｒｏｌｅＦｉｌｍＣｏａｔｅｄＧｌａｓｓｙＣａｒｂｏｎＥｌｅｃｔｒｏｄｅｓＫＡＮＧ...     

New aromatizational transformations of 4-methyl-4-trichloromethyl-substituted 2,5-cyclohexadiene triphenylphosphonium and pyridinium ylides: Abstraction or 1,6-migration of the CCl3 group

4-methyl-4-trichloromethylcyclohexadiene triphenylphosphonium ylide obtained by treatment of (1-methyl-1-tricholoromethylcyclohexa-2,4-dien-4-yl)-triphenylphosphonium bromide with BuⁿLi in THF is stabilized by the abstraction of the CCl₃ group to give (p-tolyl)triphenylphosphonium cation, which was isolated as the corresponding hydroxide. Conversely, an analogous pyridinium ylide, obtained by treatment ofZ/E stereoizomericN-(1-methyl-1-trichloromethylcyclohexa-2,5-dien-4-yl)pyridiunium bromide with a base (piperidine in CD₂Cl₂, BuⁿLi in THF), at temperatures above −40 °C, undergoes a novel high-yield aromatizational skeletal rearrangement with migration of the CCl₃ group to position 2 of the heterocycle. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 386–388, February, 1997.     

Nickel‐Catalyzed Cyclopropanation with NMe4OTf and nBuLi

Nickel was identified as a catalyst for the cyclopropanation of unactivated olefins by using in situ generated lithiomethyl trimethylammonium triflate as a methylene donor. A mechanistic hypothesis is proposed in which the generation of a reactive nickel carbene explains several interesting observations. Additionally, our findings shed light on a report by Franzen and Wittig published in 1960 that had been retracted later owing to irreproducibility, and provide a rational basis for the systematic development of the reaction for preparative purposes as an alternative to diazomethane or Simmons–Smith conditions.     

The Lifetime and Reactivity of Singlet Tetrachloropyridyl-4-nitrene

The principal direction in the photolytic decomposition of 4-azidotetrachloropyridine in methylene chloride solution involves the intermediate formation of singlet tetrachloropyridyl-4-nitrene, the lifetime of which amounts to 50 nsec. The nitrene reacts readily with the pyridine (k _pyr = 2.67·10⁷ mole^-1·sec^-1) with the formation of the corresponding pyridinium ylide, which has a characteristic absorption band in the UV spectrum with a maximum at 406 nm.     

4-Methylpyrimidinium ylides. Part 7: 3+2 Dipolar cycloadditions to non-symmetrical substituted alkenes and alkynes

The ability of 4-methylpyrimidinium ylides (as 1,3-dipoles) to react with activated non-symmetrical substituted dipolarophiles (alkenes and alkynes) is presented. 4-Methylpyrimidinium ylides did not react with alkenes. With alkynes the reactions are regiospecific, a single regioisomer being obtained. A possible mechanism for the reaction pathway is proposed. For the first time in the pyrimidinium ylides series both isomers resulting from bonding to the 2-and 6-positions of the heterocycle ring were obtained. The appropriate conditions in order to increase the selectivity of one of the isomers were determined.     

Stereoselective synthesis of 5-(4-azetidinyl)-proline esters via 1,3-dipolar cycloaddition reaction of N-metalated azomethine ylides

The conformationally locked s-trans enone functionality present in the (E)-3-arylidene-4-chromanones undergo regioselective 1,3-dipolar cycloaddition reaction with N-metalated azomethine ylides derived from β-lactam imines of glycine methyl ester in the presence of silver acetate to give spiropyrrolidines in moderate to good yield. The regio and stereochemistry of the cycloadducts have been established by single crystal X-ray structure and spectroscopic techniques.     

ZnCl2-Catalyzed [4+1] Annulation of Alkylthio-Substituted Enaminones and Enaminothiones with Sulfur Ylides

Concise construction of furan and thiophene units has played an important role in the synthesis of potentially bioactive compounds and functional materials. Herein, an efficient Lewis acid ZnCl₂ catalyzed [4+1] annulation of alkylthio-substituted enaminones is reported, that is, α-oxo ketene N,S-acetals with sulfur ylides to afford 2-acyl-3-aminofuran derivatives. In a similar fashion, [4+1] annulation of the corresponding enaminothiones, that is, α-thioxo ketene N,S-acetals, with sulfur ylides efficiently proceeded to give multisubstituted 3-aminothiophenes. This method features wide substrate scopes as well as broad functional group tolerance, offering a concise route to highly functionalized furans and thiophenes.     

Bei der Bildung metalloider Ga‐Cluster führen Phosphoniumbetaine zu einem Ga12‐Gerüst mit ungewöhnlichen Bindungsverhältnissen

During the Formation of Metalloid Gallium Clusters Phosphoniumbetaines lead to a Ga₁₂ Network with unusual Bonding Properties The reaction of a 3:1 mixture of a phosphanid and a phosphorus ylide with a metastable solution of GaBr leads to a neutral, metalloid Ga₁₂‐cluster compound. This for the frist time observed metalloid cluster with positivly polarized phosphonium ligandes and a negativly polarized Ga₁₂‐core will be disussed by quantum chemical calculations with regard to the amount of the charge transfer.     

Copper‐Catalyzed Formal [4+2] Cycloaddition of Enoldiazoimides with Sulfur Ylides

Enoldiazoimides, a new subclass of enoldiazo compounds, generate enol‐substituted carbonyl ylides whose reactions with sulfur ylides enable an unprecedented formal [4+2] cycloaddition. The resulting multifunctionalized indolizidinones, which incorporate sulfur, are formed in good yields under mild reaction conditions. The uniqueness of this transformation stems from the role of the silyl‐protected enol, since the corresponding acetyldiazoimide failed to provide any cross‐products in metal‐catalyzed reactions with sulfur ylides. This copper‐catalyzed cycloaddition is initiated with the generation of enol‐substituted carbonyl ylides and sulfur ylides from enoldiazoimides and sulfonium salts, respectively, and proceeds through stepwise six‐membered ring formation, C?O and C?S bond cleavage, and silyl and acetyl group migration.