Topomerization of substituted 1-amino- and 1-oxy-Δ2-1,2,3-triazolines

For 1-amino- and 1-oxy-²-1,2,3-triazolines, retardation (on the NMR time scale) is observed for rotation around the exocyclic N-N or N-O bond; the measured barriers to topomerization amount to 8.3–13.8 kcal/mole.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 790–794, April, 1991.     

Synthesis of 1-indolyl substituted β-carboline natural products and discovery of antimalarial and cytotoxic activities

A series of 1-indolyl substituted β-carbolines including the natural products hyrtiosulawesine, pityriacitrin and pityriacitrin B were prepared via Pictet–Spengler condensation—oxidation strategy from the corresponding indolyl-acetaldehydes and substituted tryptamines. Efforts to prepare the C-1 methylene-linked β-carboline analogues for structure–activity relationship studies were unsuccessful. Biological evaluation revealed two analogues (5 and 41) to exhibit weak inhibition of phospholipase A₂ (IC₅₀ 171 and 131 μM, respectively), two to act as antioxidants (3 and 43), and 12 analogues with activity towards a chloroquine-resistant strain (FcB1) of Plasmodium falciparum (IC₅₀ 1.0–23 μM). Testing against a panel of 60 human tumour cell lines revealed a general lack of cytotoxic effect for most of the compounds with the exception of β-carboline 42 exhibiting modest antileukaemic activity towards the HL-60(TB) cell line (LC₅₀ 4.2 μM). In addition, two novel structures (30 and 32) resulting from aldol condensation followed by Pictet–Spengler cyclisation displayed cytotoxicity with pronounced subpanel specificities towards colon cancer (COLO 205 and HCC-2998) cell lines.     

Syntheses and characterization of the noble-metal substituted heptadecatungstodiarsenates

Four Dawson type heteropolyoxotungstates substituted by noble metals with the general formula (TBA)n[As2W17M(OH2)O61], where M=PdII, RuIII, IrIV and PtIV, are prepared by filling the vacant site of the lacunary precursor a2-K10As2W17O61. UV-vis and IR spectra are similar to the other transition metal substituted Dawson type tungstodiarsenates. EPR result provides direct evidence to identify the presence of noble metal cation. Electrochemical behavior investigated by cyclic voltammetry in acetonitrile displays four reversible one-electron redox couples attributed to the W(VI-V) process of tungsten-oxo framework.     

Photochromic reactions of pyrryl substituted fulgides and fulgimides

Photochromic behaviour of six pyrryl substituted fulgides and one fulgimide has been examined. The substituents have significant effects on their photochromic processes. The results of steady state kinetics show that the photodecoloration of the colored form, 7,7a-dihydroindole derivatives (II) follows the first-order kinetics. The substituents have certain effects on the rate constant of the photodecoloration. As for the colored form (II), compounds with the substituent at 2- or 3-position have larger rate constants of the decoloration than those of non-substituted ones. The photocoloration reactions are more complicated and do not fit the simple kinetics. Introduction of the electron donating substituent into the 2- or 3-position leads to bathochromic shift of the maximum of absorption (λmax) of 7,7a-dihydroindole derivatives. For example, the λmax of compound II 7 is 720 nm in acetonitrile. The increasing of the polarity of the solvent caused a remarkable bathochromic shift of λmax of the colored     

Synthesis of esters ofpara-hydroxy substituted α-trifluoromethylmandelic acids

Methyl trifluoropiruvate in trifluoroacetic acid at 20 °C rapidly C-hydroxyalkylates various phenols at thepara-positions to afford the corresponding esters ofpara-hydroxy substituted -trifluoromethylmandelic acids.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 528–530, March, 1995.The present study was carried out with the financial support of the Russian Foundation for Basic Research (Project code 93-03-22696).     

Stereoselective synthesis of N-phenylsulfonyl substituted spiro-β-lactams

A stereoselective synthesis of N-phenylsulfonyl substituted spiro-β-lactams obtained from the N-(phenylmethylene)benzenesulfonamide and the ketene valence tautomer of the bicyclic mesoionic compounds derived from 4-hydroxy substituted N-acyl-l-prolines in the presence of acetic anhydride as the dehydrating agent is presented. The reaction of (2S,4R)-4-acetyloxy or benzoyloxy-N-acyl-proline with the above imine afforded a mixture of two diastereoisomeric spiro-β-lactams with complete stereoselectivity for the spiro carbon.     

An efficient synthesis of substituted benzene-1,2-dicarboxaldehydes

Substituted-benzene-1,2-dicarbaldehydes were synthesized by the reaction of substituted-1,2-bis(dibromomethyl) benzenes with fuming sulfuric acid,followed by hydrolysis. The yields were signifi-cantly improved by introducing solid sodium bicarbonate into the reaction mixture before hydrolysis and workup.     

Solvent-free synthesis of substituted thiopyrans via multicomponent reactions of α-haloketones

A straightforward and efficient method for the synthesis of thiopyran derivatives via three-component reaction of alkyl propiolate, benzoylisothiocyanate or its derivatives and α-haloketones in the presence of triphenylphosphine under solvent-free conditions at 70℃ without using any catalyst is reported, The method offers several advantages including high yields of products and an easy work-up procedure.     

Synthesis of 4-vinyl substituted β-lactams of the oxamazin family

4-Vinyl-substituted oxamazins 15,16, and 3 have been prepared. Key steps of the synthesis are: the preparation of protected α-amino-β-hydroxyacid 6 through ester enolate condensation of ethyl glycinate STABASE adduct 8 with CH-protected propiolaldehyde 9, the coupling of this acid with an appropriate protected hydroxylamine, the cyclization of resulting hydroxamate, and finally the acylation of the amino-group in 3 with ATMO side chain.     

Room temperature syntheses of entirely diverse substituted β-fluorofurans

Synthesis of highly substituted 3-fluorofurans is reported. The sequence began with preparation of tert-butyldimethylsilyl alk-1-en-3-yn-1-yl ethers from 1,4-disubstituted alk-3-yn-1-ones. Subsequent fluorination of alkenynyl silyl ethers with Selectfluor gave 2-fluoroalk-3-yn-1-ones in almost quantitative yield. Subsequent 5-endo-dig cyclizations using chlorotriphenylphosphine gold(I)/silver trifluoromethanesulfonate (5/5 mol%), N-bromo- or N-iodosuccinimide and gold(I) chloride/zinc bromide (5/20 mol%), all at room temperature, provided a facile method for the generation of substituted 3-fluoro-, 3-bromo-4-fluoro-, and 3-fluoro-4-iodofurans in good yields. Also, 2,2-difluoroalk-3-yn-1-ones were prepared by fluorination of alk-3-yn-1-ones under organocatalytic conditions. The structures of (Z)-tert-butyldimethylsilyl but-1-en-3-yn-1-yl ether, 3-bromo-4-fluorofuran, and 3-fluoro-4-(phenylethynyl)furan were confirmed by X-ray crystallography.     

One-step synthesis of functionally substituted Δ3-pyrrolidones-2

3-Amino-4,5-dicarboalkoxy-³-pyrrolidon-2-yl-5-acetic acid esters were prepared from N-alkylamino- and aminofumaric diesters in nonaqueous medium using acidic catalysts.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Dnepropetrovsk Institute of Chemical Engineering, Dnepropetrovsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 167–169, January, 1992.     

A new Knoevenagel-type synthesis of fully substituted γ-hydroxybutenolides

The synthesis of fully substituted γ-hydroxybutenolides is possible by a Knoevenagel-type ring condensation of α-methyleneketones and α-ketoesters under basic conditions. This novel transformation allowed the preparation of di-aryl/heteroaryl substituted hydroxyfuranones, such as 20 and 27, which are important intermediates for pyridazine fungicides. As it turned out, a whole range of different substituents, such as alkyl, cycloalkyl, aryl, heteroaryl and ester groups could be linked to the butenolide scaffold, demonstrating the broad scope of the novel cyclization.     

Inclusion of chemotherapeutic agents in substituted ��-cyclodextrin derivatives

The stabilities of the inclusion compounds of three chemotherapeutic agents, camptothecin (CPT), docetaxel (DOC) and idarubicin (IDA), plus a model compound 1,4-dihydroxyanthraquinone (DHA) with several ??-cyclodextrin (??-CD) derivatives were investigated by solubility measurements, isothermal titration microcalorimetry and fluorescence anisotropy measurements. Ionic heptakis-(6-deoxy-6-thioethers) of ??-CD were found to exhibit very high binding potentials for these drugs making them to good candidates for advanced drug delivery.     

Synthesis of substituted dihydro-1H-pyrazoles and 1H-pyrazoles via formal [4+1] annulation of α-arylhydrazonoketones and dimethyl sulfonium methylides

A formal [4+1] annulation of readily available α-arylhydrazonoketones and dimethyl sulfonium methylides is described, which involving tandem ylide-mediated addition and nucleophilic cyclization reactions. This transformation features mild reaction conditions, simple execution, good to high yields, and provides straightforward synthesis of substituted dihydro-1H-pyrazoles and 1H-pyrazoles via C-C and C-N bond formation.     

Magnetotransport properties of Mo substituted La0.7Ca0.3Mn1−xMoxO3 perovskites

We studied the effects of Mo substitution on the structural, transport, and magnetic properties of the La_0.7Ca_0.3Mn_1−xMo_xO₃ (x ≤ 0.1) samples. Powder X-ray diffraction analysis reveals that the samples studied crystallize in the orthorhombic structure with space group Pbnm. Both particle size and morphology change significantly as the Mo content x varies. The metal-insulator transition temperature (T_MI) and Curie temperature (T_C) decrease monotonically as x increases. Magnetization data reveal that long-range FM ordering persists in all samples and the saturation moment decreases linearly as x increases. The smaller depression rate of dT_C/dx observed is mainly ascribed to the increased amount of Mn²⁺ ions with Mo doping, which opens the FM coupling between Mn²⁺–O–Mn³⁺ in the samples.     

Regiochemistry of the ring expansion of unsymmetrically substituted ketones involving β-hydroxyalkylselenides

β-hydroxyalkylselenides derived from unsymmetrically substituted ketones have been rearranged to substituted ketones in the presence of soft electrophiles such as silver tetrafluoraborate or dichlorocarbenes. Although the migration of the more substituted carbon often prevails, subtle variations have been observed depending upon the structure of the starting material and the experimental conditions used.     

Synthesis of multisubstituted 1H-pyrrole: selenium-catalyzed reaction of γ-nitro substituted carbonyl compounds and carbon monoxide

The novel and efficient selenium-catalyzed reductive N-heterocyclization of γ-nitro substituted carbonyl compounds with carbon monoxide has been developed. Various multisubstituted 1H-pyrroles can be easily prepared by this protocol. The one-pot synthesis of ethyl 1H-pyrrole-3-carboxylate derivatives was also successfully attained by the selenium-catalyzed reaction of β-ketoester, vinyl nitro compounds and carbon monoxide.     

1H NMR study of inclusion of substituted bicyclo[3.3.1]nonanes in α- and β-cyclodextrins

The interaction of 2,6-disubstituted bicyclo[3.3.1]nonanes with - and -cyclodextrins has been investigated by¹H NMR spectroscopy and the formation of (11) host—guest complexes has been established.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2523–2525, December, 1995.