Reaction of carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride

Reaction of various carbonyl compounds with xenon difluoride in the presence of silicon tetrafluoride was investigated. Aromatic aldehyde, ketones, and α-ketoester react with xenon difluoride to give α,α-difluoroalkyl phenyl ethers. However, acid fluoride, ester, acid cyanide, α-ketocarboxylic acid, or thioester do not afford the corresponding products. In the case of cinnamaldehyde, fluorination was accompanied by intramolecular cyclization to afford fluorinated epoxide.     

Preparation of 2-aryl and 2-aryloxymethyl imidazo[1,2-a]pyridines and related compounds

A series of substituted 2-aryl imidazo[1,2-a]pyridines has been prepared in which a variety of substituents are introduced on the 4′-position of the phenyl ring and on the 3, 5 , 6 or 7 position of the heterocyclic ring. Most examples have acetamido, bromo, cyano, or formyl substituents at the 4′-position. Analogous imidazo-[2,1-b]fhiazoles and imidazo[1,2-a]pyrimidines have also been prepared. Another series of compounds consisting of 4′-formylphenoxymethyl derivatives of imidazole, the three positional isomers of pyridine, thiazole, benzimidazole and ring-substituted imidazo[1,2-a]pyridines has been prepared. 2-(4′-Formylphenylethenyl) derivatives of imidazole and imidazo[1,2-a]pyridine were also prepared.     

Heterocyclizations with tosylmethyl isocyanide derivatives. A new approach to substituted azolopyrimidines

An efficient synthesis of substituted azolopyrimidines such as pyrido[3',2':4,5]pyrrolo[1,2-c]pyrimidines, pyrimido[1,6-a]indoles, benzo[4,5]imidazo-[1,2-c]pyrimidines, an imidazo[1,2-c]pyrimidine, and pyrazolo[1,5-c]pyrimidines is described. The method involves the reaction of N-protected bromomethylazoles and tosylmethyl isocyanide (TosMIC) derivatives in nonanhydrous media. The study of the reaction conditions shows that the method is only successful under phase-transfer conditions (CH2Cl2/30% aq NaOH) using benzyltriethylammonium chloride as a catalyst.     

The consequences of cation-radical fluorination theory—II : Fluorination pathways with less-reactive reagents

The fluorination of benzene with caesium tetrafluorothallate and of pyridine or benzo[b] furan with caesium tetrafluorocobaltate gives sequences of polyfluoroaromatics with vicinal fluorines. Polynuclear aromatics are fluorinated by caesium or potassium tetrafluorocobaltate to give products containing little or no hydrogen, whereas the stronger fluorinating agent cobalt trifluoride gives products which contain much hydrogen. These two previously unexplained features are rationalized by a mechanism which involves 1,2-migrations of fluorine in cyclohexadienyl-type radicals or cations, and is backed up by CNDO/2 calculations. This rationalization implies significantly different rates of atom or ion migrations through the lattices of the different solid fluorinating agents.     

A New Method for the Preparation of Sulphuryl Chloro Fluoride

It has been observed that a suspension of sodium fluoride in boiling acetonitrile could be used for the preparation of fluorine compounds such as silicon tetrafluoride [1], thiophosphoryl fluoride [2], sulphur tetrafluoride [3,4], and fluorocyclophosphazenes [5]. This method, when adopted for the fluorination of sulphuryl chloride [6], it is observed that a mixture of sulphuryl fluoride and sulphuryl chloro fluoride is obtained. On the other hand, when lead fluoride is substituted for sodium fluoride, pure sulphuryl chloro fluoride is evolved. Based on this observation, a new method has been standardised for the preparation of a pure sample of sulphuryl chlorofluoride by fluorinating sulphuryl chloride by lead fluoride in acetonitrile medium.     

On the reaction of 4-substituted trimethyltin aromatics with perchlorylfluoride

To evaluate the suitability of [¹⁸F]perchorylfluoride [¹⁸F]FClO₃ as an electrophilic fluorination agent for the preparation of radiopharmaceuticals, the reactivity non-radioactive FClO₃ towards 4-substituted trimethyltin aromatic compounds was studied. Contrary to the expectation, an electrophilic fluorination of the aromatic nucleus did not occur. The reaction of perchlorylfluoride with aromatic trimethylstannyl compounds resulted in the formation of trimethyltin fluoride and the respective destannylated aromatics in variable yields.     

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.     

Fluorination with xenon difluoride. Reactions of phenyl-substituted olefins in the presence of trifluoroacetic acid

Trifluoroacetic acid-catalyzed liquid-phase fluorination with xenon difluoride of phenyl-substituted olefins, e.g. cis- and trans-1-phenylpropene and cis- and trans-stilbene, results in the formation of vicinal difluorides and fluoro-trifluoroacetates. The reaction is non-stereospecific. d,1-Erythro and d,1-threo fluoro-trifluoroacetates are formed in a highly regiospecific Markovnikov manner in 50% yield. The formation of β-fluorocarbonium ions is suggested.     

室温下Cu掺杂的ZnO纳米粉末催化多组分一锅法合成完全取代的茚并[1,2-b]吡啶(英文)

Cu doped ZnO nanocrystalline powder(10 mol%) has been found to be an efficient catalyst for the one‐pot multi‐component synthesis of fully substituted new indeno[1,2‐b]pyridines through a com-bination of 1,3‐indandione, propiophenone or acetophenone derivatives, aromatic aldehydes, and ammonium acetate in ethanol/H2 O at room temperature. The methodology is mild, efficient and high to excellent yielding.     

Novel enantioselective fluorinating agents, (R)- and (S)-N-fluoro-3-tert-butyl-7-nitro-3,4-dihydro-2H-benzo[e][1,2]thiazine 1,1-dioxides

Enantioselective fluorinating agents, (R)- and (S)-,N-fluoro-3-tert-butyl-7-nitro-3,4-dihydro-2H-benzo[e][1,2]thiazine 1,1-dioxides (BNBT-F, 2) are readily prepared in 3 steps from racemic 3-tert-butyl-7-nitro-3,4-dihydro-2H-benzo[e][1,2]thiazine 1,1-dioxides (5) via optical resolution and fluorination. These agents make accessible both enantiomers of optically active quaternary alpha-fluoro carbonyl compounds in modest to high enantioselectivities. X-ray crystallographic analysis of chiral 2 reveals a unique structure wherein the nitrogen atom is highly pyramidalized and fluorine occupies an axial position.     

An investigation of the minimal structural conditions lor the dirnroth-type rearrangement in the polyazaindolizine series

In the imidazo[1,2]diazine series, only the imidazo[1,2-a]- and [1,2-c] pyrimidine systems were found to undergo a Dimroth-type rearrangement under basic aqueous conditions. The electronic and steric factors influencing the rearrangement rates of methyl substituted imidazo-[1,2-a] pyrimidines are discussed.     

Fluorination of poly(p-phenylene) using TbF4 as fluorinating agent

The fluorination using TbF₄ as fluorinating agent was successfully performed on poly(p-phenylene). The method allows the fluorine content of the polymer to be controlled and the formation of structural defects, such as dangling bonds, to be significantly decreased by comparison with the direct fluorination using pure F₂ gas. The aromatic character of the phenyl ring is partly maintained through the fluorination contrary to the direct fluorination (using pure F₂ gas), for which a quasi-perfluorination and a partial decomposition of the polymer occur. Complementary analytical techniques have been used, such as ¹⁹F and ¹³C solid state NMR, FT-IR and EPR to compare the samples as a function of the reaction conditions.     

Selective fluorination of substituted trichloromethyl benzenes by HF in liquid phase: Preparation of fluorinated building blocks

The selective fluorination by successive Cl/F exchanges of α,α,α-trichlorotoluene, substituted or not by a chlorine atom, was studied in the presence of HF as the fluorinating agent. The influence of the presence of a catalyst or a basic solvent (such as dioxane, pyridine, tributylphosphate) in order to control the fluorination was also investigated. In mild conditions (50 °C and after 1 h of reaction), HF in excess was required in order to obtained the trifluoromethylation by Cl/F exchanges. The presence of SbCl₅ in small amount activated the Cl/F exchanges and only a stoichiometric amount of HF was required whatever the chlorinated molecules. Selective mono and difluorination could be obtained by using basic solvents.     

Condensed heterocyclic systems with a thiazole ring. 11. Thiazolo [3,4-b]-1,2, 4-triazinones

Syntheses are reported for substituted 2-oxo-1,2-dihydrothiazolo[3,4-b]-1,2,4-triazinium salts. The action of bases on these salts leads to the corresponding mesoionic compounds.For communication 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1497–1500, November, 1985.     

Synthesis of 2,2''''-(Substituted Arylmethylene)bis(1,6,6-trimethyl- 6,7,8,9-tetrahydrophenanthro[1,2-b]furan-10,11-dione) Derivatives

Tanshinones are a series of quinone diterpenes which are isolated from Salvia miltiorrhiza Bunge known as “Danshen” in Chinese traditional medicine. They have broad pharmacological activities, such as antibacterial, anti-tumor and anti-platelet aggregation1. Tanshinones’ derivatives have been used to treat the coronary disease, cerebrovascular diseases as well as neurasthenic insomnia in clinic2. Tanshinone IIA is one of the main components of tanshinones and characterized by the presenc…     

Synthesis and properties of methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole

The synthesis and full characterization of new derivatives of indolo[3,2-b]carbazole with differently substituted phenyl groups at nitrogen atoms is reported. Comparative study on their thermal, optical electrochemical, and photoelectrical properties is presented. The synthesized compounds are electrochemically stable. Their highest occupied molecular orbital energy values range from -5.14 to -5.07 eV. The electron photoemission spectra of the films of synthesized materials revealed the ionization potentials of 5.31-5.47 eV. Hole drift mobility of the amorphous film of 5,11-bis(3-methoxyphenyl)-6-pentyl-5,11-dihydroindolo[3,2-b]carbazole exceed 10(-3) cm(2)/V·s at high electric fields, as it was established by xerographic time-of-flight technique. In contrast to diphenylamino substituted derivatives of carbazole, no effect of the position of methoxy groups on the photoelectrical properties was observed for the synthesized methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole. The indolo[3,2-b]carbazole core has a larger resonance structure that includes 3 phenyl rings, and thus the energy gap of the HOMO and LUMO π orbitals is lower as compared to that of carbazoles. With a larger energy difference between the phenyl substituents and the core moiety, the indolo[3,2-b]carbazole derivatives studied all have a weaker coupling between the phenyl group and a much weaker dependence of the molecular properties on the position of substituents on the phenyl groups as compared to those observed in substituted carbazoles.     

Ruthenium-catalyzed oxidative cleavage of olefins to aldehydes.

Three oxidation protocols have been developed to cleave olefins to carbonyl compounds with ruthenium trichloride as catalyst (3.5 mol %). These methods convert olefins that are not fully substituted to aldehydes rather than carboxylic acids. While aryl olefins were cleaved to aromatic aldehydes in excellent yields by using the system of RuCl3-Oxone-NaHCO3 in CH3CN-H2O (1.5:1), aliphatic olefins were converted into alkyl aldehydes with RuCl3-NaIO4 in 1,2-dichloroethane-H2O (1:1) in good to excellent yields. It is noteworthy that terminal aliphatic olefins were cleaved to the corresponding aldehydes in excellent yields by using RuCl3-NaIO4 in CH3CN-H2O (6:1).     

Design,synthesis, pharmacological evaluation and DNA interaction studies of binuclear Pt(II) complexes with pyrazolo[1,5‐a]pyrimidine scaffold

Substituted pyrazolo[1,5‐a]pyrimidine ligands were synthesized by cyclization, using 3‐(thiophen‐2‐yl)‐1H‐pyrazol‐5‐amine with substituted enones (3‐phenyl‐1‐(pyridin‐2‐yl)prop‐2‐en‐1‐one) in presence of KOH and DMF as solvent to form cyclic aromatic compounds. The substituted pyrazolo[1,5‐a] pyrimidine based binuclear Pt^II complexes containing neutral tetradentated ligands have general formula [Pt₂(5a–5f)Cl₄], (where, (5a ‐5f) = pyrazolo[1,5‐a] pyrimidine ligand). This compounds were characterized by physicochemical and spectroscopic method like elemental analyses, UV‐Visible, FT‐IR, EDX, TGA, molar conductivity, magnetic susceptibility measurements, mass spectroscopy, ¹H and ¹³C NMR method. The square planar geometry was predicted by electronic spectral study. All Pt^II compounds were evaluated by antimicrobial assay, in vitro brine shrimp assay, in vivo cellular level bioassay using S. Pombe cells and anti‐tuberculosis study. LC₅₀ (50% lethal concentration) values of compounds are observed between 6.450 ‐ 102.07 μg/mL. UV‐vis absorption titration, competitive displacement assay, molecular docking and viscosity measurement were carried out to examine the binding type and binding strength of complexes. The binding studies suggest partial intercalative binding mode of the complexes and the observed binding constant (K_b) values are found in the order of 6d > 6b > 6c > 6a > 6e > 6 f. The anti‐proliferative cytotoxicity of the synthesized Pt^II complexes (6a‐6f) were tested against the HCT‐116 (Human Colorectal Carcinoma) cancer cell line.     

Organic luminophores of the pyrazoline series with two unconjugated fluorophores

Condensation of 1-(p-formylphenyl)-3,5-diphenyl-2-pyrazoline with 4-acetyl-N-phenylnaphthalamide and a mixture of 3- and 4-acetyl-7H-benzimidazo [1,2-b] benz-[de]isoquinolin-7-ones and subsequent heating of the products with phenylhydrazine were used to synthesize luminophores with orange and orange-red luminescence that have high quantum yields in aromatic solvents. Intramolecular transfer of the electronic excitation energy is observed for these compounds in toluene.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1248–1250, September, 1982.     

High functionalization of 5-nitro-1H-imidazole derivatives: the TDAE approach

We report herein the synthesis of substituted 2-[4-(1,2-dimethyl-5-nitro-1H-imidazol-4-yl)phenyl]-1-arylethanols, ethyl 3-[4-(1,2-dimethyl-5-nitro-1H-imidazol-4-yl)-phenyl]-2-hydroxypropanoate and 2-[4-(1,2-dimethyl-5-nitro-1H-imidazol-4-yl)benzyl]-2-hydroxy-acenaphthylen-1(2H)-one from the reactions of 4-[4-(chloromethyl)phenyl]-1,2-dimethyl-5-nitro-1H-imidazole with various aromatic carbonyl and a-carbonyl ester derivatives using tetrakis(dimethylamino)ethylene (TDAE) methodology.