Synthesis of Novel Quinazoline Derivatives as Antimicrobial Agents

Quinazoline isothiocyanate 1 reacts with various nucleophiles(nitrogen nucleophiles,oxygen nucleophiles and sulphur nucleophiles)to afford heterocyclic systemes 2-13,Also,the [4 2] cycloaddition reaction of 1 with phenyl isocyanate,benzylidene aryl amine and cinnamic acid derivatives gave novel heterocyclic compounds 14-16,Moreover,the reaction of 1 with active methylene compounds under Michael reaction conditions also was investigated to yield 17 and 18 and it was found that all these reactions proceede via isothiocyanate heterocyclization to furnish non-condensed heterocyclic compoundes,Some of the newly synthesized compounds were tested for their antimicrobial activities.     

Stable σH-adducts in reactions of ferrocenyllithium with azines

Stable σ^H-adducts as intermediates of the nucleophilic substitution of hydrogen in 3-(2-pyridyl)-1,2,4-triazines were obtained for the first time using ferrocenyllithium as a nucleophilic reagent. The three-dimensional structures of the reaction products were established based on the X-ray diffraction study of 1-[4-ethyl-6-phenyl-3-(2-pyridyl)-5(H)-1,2,4-triazin-5-yl]ferrocene.     

A Convenient Synthesis of Aromatic Fluoride by Thermal Stable Pyridinium Phase-transfer Catalyst

Fluoroorganic compounds have been applied as useful intermediates in industry. Here, we use the PTC method for fluorination of aromatic halide by inorganic fluorides involv- ing a halogen-exchange. This is a convenient and attractive synthetic way to obtain fluoro compounds, because inorganic fluorides such as potassium fluoride is safe to be handled and cheap1. However, owing to poor solubilities of inorganic fluorides in organic solvents, the halogen-exchange fluorination often requires …     

Assembly Synthesis of Sheet-like Calcite Array and Stable Vaterite by Supported Liquid Membrane

Sheet-like calcite array and stable vaterite were synthesized by bio-mimetic supported liquid membrane system under different reaction conditions. Both of the FTIR spectra of products showed narrower peak at 1418 cm^-1 than that of bulk CaCO3, and that of vaterite has a split in this peak.     

1H NMR Detection of σ-Adducts in S NH Reactions of Nitroquinolines with Chloromethyl Phenyl Sulfone

The intermediate -adducts of chloromethyl phenyl sulfone with 3-nitro-, 5-nitro-, 6-nitro-, 7-nitro- and 8-nitroquinoline are detected by ¹H NMR spectroscopy.     

Synthesis and structure of penta-platinum σ-bonded derivatives of corannulene

The synthesis of a new class of Pt(II) complexes with corannulene by way of either oxidative addition or reductive coupling is reported and their crystal structures are investigated. The crystal structure for {trans-Pt(PEt₃)₂Cl}₄{cis-Pt(PEt₃)₂Cl}C₂₀H₅ (1) consists of two enantiomers in a unit cell and shows cis- and trans-configuration around Pt(II) due to bulky PEt₃ ligands. The pentanuclear Pt(II) complex, 1, readily reacts with 1-ethynyl-4-nitrobenzene to afford the penta-alkynyl substituted Pt(II) complex (2). Although there are still bulky PEt₃ ligands around the Pt atoms in 2, all five Pt(II) have trans-configurations. The bowl of corannulene in 2 is shallower than that of 1. Therefore, the bowl depth of corannulene plays a key role in the determination of molecular geometry of σ-bonded pentanuclear complexes bearing corannulene.     

Synthesis of δ-Valerolactone Using Stable Hydrogen Peroxide Derivatives

Russian Journal of Organic Chemistry - The efficiencies of hydrogen peroxide derivatives in the Baeyer–Villiger oxidation of cyclopen­tanone to δ-valerolactone have been compared....     

Fluorination of anionic σ-complexes by cesium fluoroxysulfate

Anionic -complexes and related structures react with cesium fluoroxysulfate to give predominantly the C-fluoro derivatives: fluoronitrocyclohexadienes or substituted fluoronitrobenzenes. Oxidation or degradation of a complex to form substituted nitrobenzenes is also possible. The balance between all these processes is determined by the structure of the original complex.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1615–1619, July, 1991.     

Stable σH-adducts in the reactions of the acridinium cation with heterocyclic N-nucleophiles

A reaction of NH-heterocycles with the 10-methylacridinium cation in the presence of a base led to 9,10-dihydro-10-methyl-9-substituted acridines, which can be considered as stable intermediates in the aromatic nucleophilic substitution reaction of hydrogen. The structure of the intermediates was studied and their oxidation potentials were determined. Generally, the oxidation potential was found to symbatically change with the changes in the energy of HOMO.     

Synthesis and Reactivity of the First Stable λ5-Phosphaacetylene

Abstract

The synthesis and reactivity of he P-bis(diisopropylamino) trimethylsilylphosphaacetylene (bp 75–80°C/10^?2) is reported. Addition of trimethylsilyltriflate to this compound leads to a stable methylenephosphonium salt which has been characterized by an X-ray diffraction study.     

Heck Arylation of Cyclohexene Promoted by Ultrasonic and Micro wave in Ionic Liquid： a Novel Method of the Synthesis of 3-Naphthylcyclohexene

Palladium catalyzed arylation or vinylation of olefins by aryl halides are well known as the Mizoroki-Heck reaction and have proved to be of genuine synthetic utility for C-C bond formation1. Although a lot of progress has been made in Heck coupling react…     

Stable σ-adducts of 4,6-dinitrotetrazolo[1,5-a]pyridine with alkoxide anions

The reaction of 2-chloro-3,5-dinitropyridine with two equivalents of KN₃ in the presence of ROH results in stable Meisenheimer-type -adducts of 4,6-dinitrotetra-zolo[1,5-a]pyridine with RO^– anions (R = H, Alk, Ph). The mechanism of -complex formation was suggested. The structure of the -adduct with R = Me was established by IR and NMR spectroscopy and by X-ray diffraction analysis.For the preliminary communication, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1278–1283, July, 1994.This work was supported by the Russian Foundation for Basic Research (project code 93-03-5329).     

How Stable Are Epoxides? A Novel Synthesis of Epothilone B

Remarkable stability of the oxirane function is displayed over a number of synthetic operations in a novel synthesis of the antitumor compound epothilone B (see scheme). The cis-epoxide, generated very early by dihydroxylation of an (E)-olefin, was resistant to more than ten synthetic steps under a wide variety of reaction conditions. TBS=tert-butyldimethylsilyl.     

C−F Arylation of Polyfluorophenols by Means of Sigmatropic Dearomatization/Defluorination Sequence

Selective C−F arylation of polyfluorophenols with aryl sulfoxides has been accomplished by means of a sigmatropic dearomatization/defluorination sequence. This sequence consists of three processes: 1) interrupted Pummerer reaction to form S−O-tethered sulfonium salt; 2) C−C-forming [3,3] sigmatropic rearrangement with dearomatization; and 3) Zn-mediated defluorinative rearomatization. The present biaryl construction provides a facile access to polyfluorinated biaryls that is difficult to synthesize by other methods. The synthetic utility of the strategy is clearly demonstrated by the synthesis of a fluorinated analogue of Maxipost, a potassium channel modulator.     

Influence of polar modifiers on microstructure of polybutadiene obtained by anionic polymerization. Part 5: Comparison of µ, σ, σ+µ, and σ−µ complexes

A comparison was performed of the influence of polar modifiers forming (separately or simultaneously) σ and μ complexes with a living center during anionic polymerization of 1,3-butadiene — regarding the content and distribution of butadiene isomeric structures. Analysis of the ¹H NMR, ¹³C NMR, and FT-IR data indicated a significant discrepancy in terms of the determination of the polybutadiene microstructure depending on the analytical method applied. Nevertheless, it was observed that the application of polar modifiers forming different types of complexes with organometallic compounds provided the possibility to govern the content of 1,4- and 1,2-butadiene units in a very broad range (0.55 < cis/trans < 1.05 and 10% < vinyl < 90%, respectively) as well as to control diad distribution.     

C?H Bond Arylation in the Synthesis of Aryltetralin Lignans: A Short Total Synthesis of Podophyllotoxin

A short total synthesis of podophyllotoxin, the prototypical aryltetralin lignan natural product, is reported. Key to the success of this synthetic pathway is a Pd‐catalyzed C(sp³)–H arylation reaction enabled by a conformational biasing element to promote C–C reductive elimination over an alternative C N bond‐forming pathway. This strategy allows for access to the natural product in five steps from commercially available bromopiperonal, and sheds light on subtle conformational effects governing reductive elimination pathways from high‐valent palladium centers.     

Copper-Catalyzed Asymmetric Arylation of α-Substituted Cyanoacetates Enabled by Chiral Amide Ligands

The (S)-nobin-embodied picolinamide and L-hydroxyproline-derived amide are effective ligands for Cu-catalyzed enantioselective coupling reaction of (hetero)aryl iodides with α-alkyl substituted cyanoacetates. This arylation reaction gave α-(heteroaryl)-α-alkyl cyanoacetates in good to excellent enantioselectivities (up to 95 % ee). A variety of functionalized (hetero)aryl and alkyl groups could be introduced to the quaternary center and therefore provided a valuable tool for preparing enantioenriched compounds with an all-carbon quaternary center tethered with convertible functional groups. The size of both α-alkyl and ester groups was proven as the key factor for asymmetric induction.     

Synthesis of EPR-g-styrene by anionic coupling technique

Ethylene-propylene rubber (EPR) graft copolymers were prepared successfully by anionic coupling technique between chlorinated EPR (Cl-EPR) and living anionic polystyrene chain.The EPR-g-styrene was characterized by hydrogen nuclear magnetic resonance (~1H NMR) and gel penetration chromatogram (GPC).     

Synthesis of 2-Methylenesuccinimides Modified by Germatranes

Ｓｙｎｔｈｅｓｉｓｏｆ２－ＭｅｔｈｙｌｅｎｅｓｕｃｃｉｎｉｍｉｄｅｓＭｏｄｉｆｉｅｄｂｙＧｅｒｍａｔｒａｎｅｓＺｈｏｎｇＢｉａｏＺＨＡＮＧ；ＲｕＹｕＣＨＥＮ（ＩｎｓｔｉｔｕｔｅｏｆＥｌｅｍｅｎｔｏ－ＯｒｇａｎｉｃＣｈｅｍｉｓｔｒｙＮａｎｋａｉＵｎｉｖ...     

Highly Diastereoselective Synthesis of Anomeric β-O-Glycopyranosyl σ3λ3-and σ4λ5-Phosphorus Compounds

Abstract

A new method for the highly stereoselective synthesis of β-O-σ³λ³ and σ⁴λ⁴ phosphorus-substituted 2,3,4,6-tetrabcnzylglucose is presented. The β-diastereoselective synthesis of the carbohydrates containing σ³λ³ and σ⁴λ⁵ phosphorus groups could be accomplished via two main synthetic routes. The first involves the addition of the σ³λ³-phosphorus derivative 3 to the 2,3,4,6-tetrabenylglucose derivative 1 (αβ = 1:l) in toluene and triethylamine as a catalyst to provide the σ³λ³ phosphorus derivative 4 with practically 100% β-diastereoselectivity.