Crystalline Methyl β-L-Pfamnofuranqside From Fischer Glycqsidatiok of L-Rhamnose

Flash chromatography of the mixture obtained by reaction of L-rhamnose with methanol in the presence of cation-exchange resin, in addition to methyl α-L-rhamnofuranoside (3) and methyl rhamnopyranosides 1 and 2 gave methyl β-L-rhamnofuranoside (4) in 8% yield. ¹³C and ¹H NMR spectra of 3 and 4 as well as their calculated conformation in solution are discussed.     

Reaction of levoglucosenone with Dane’s diene

Cycloaddition of levoglucosenone to 7-methoxy-4-vinyl-1,2-dihydronaphthalene has been studied under different conditions, including heating under atmospheric pressure, in a sealed ampule, and under high pressure, as well as under microwave irradiation and in the presence of various catalysts. The chiral Diels–Alder adduct thus obtained can be used in the synthesis of estrone and its analogs.     

Oxidation of bicyclic monoterpene ketones with Caro’s acid

Previously unknown seven-membered lactones, (1R,1??R,5S,5??S)-5,5??-oxybis(1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one), 2,2-dimethyl-1,6-dioxaspiro[2.6]nonan-7-one, 4-(1-hydroxy-1-methylethyl)-7-methyloxepan-2-one, and (4R,4??R,7S,7??S)-4,4??-[oxybis(propane-2,2-diyl)]bis(7-methyloxepan-2-one), were synthesized by the Baeyer-Villiger reaction using Caro??s acid as a result of oxidative and skeletal transformations of bicyclic monoterpene ketones, (+)-camphor, (+)-nopinone, and (?)-isocaranone.     

Reactions of Zincke’s salts with 2,3-dimethylbenzothiazolium iodide

Reactions of 1-(2,4-dinitrophenyl)pyridinium chloride and 2-(2,4-dinitrophenyl)isoquinolinium chloride with 2,3-dimethylbenzothiazolium iodide in hot pyridine allows introduction of an aryl residue into the thiazole ring via intermolecular transformation of the pyridine ring of Zincke’s salts with participation of the methyl group in position 2 of the benzothiazolium salt.     

Acylation of phenols with γ-chlorobutyroyl chloride and transformations of the reaction products

Alkylphenols afford only O-acyl derivatives on treatment with -chlorobutyroyl chloride in the presence of both Et₃N and AIC1₃ at 20–60 °C. They cyclize under the action of K₂CO₃ in DMSO into the respective cyclopropanes and undergo Fries rearrangement on heating with AICl₃ at 120 °C into C-acyl derivatives.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1023–1025, April, 1996.     

Study of Selected Spectral Properties and Complex Formation with Transition Metals Ions of a New Schiff’s Base Containing Fluorescein and Sulfamide Fragments

Russian Journal of General Chemistry - A new azomethine based on N-aminofluorescein and ortho-tosylaminobenzaldehyde has been synthesized. Structure and properties of the obtained compound have...     

Comparison of the Reactivities of Tyrosine–Proline-Based Dipeptides toward Acylation with Nitrophenyl Benzoates

Russian Journal of Organic Chemistry - The reactivities of the L-Tyr–L-Pro dipeptide and its analog with a hydroxymethyl group instead of carboxy group in the proline moiety were compared by...     

Synthesis of Copolymers of Unsaturated β-Diketones with Styrene and Methyl Methacrylate

Copolymerization of styrene and methyl methacrylate with various unsaturated -diketones was studied. The influence exerted by the reaction temperature, structure of -diketone, and its content in the comonomer mixture on the kinetic parameters of copolymerization and molecular weights of the products was examined.     

Features of Reactions of Some 1-Arylaminomethylisatins with Girard’s Reagent T

Depending on the structure of the substituent at the endocyclic nitrogen atom, the reactions of aminomethylisatins with the Girard’s reagent T can proceed both with the elimination of the aminomethyl group and with its retention resulting in the formation of the corresponding positively charged isatin-3-acylhydrazones.     

Synthesis of Dendritic Schiff Base Ligands for Titanium Catalyzed Enantioselective HDA Reaction of Danishelfsky‘ s Diene with Aldehydes

A new type of dendritic NOBIN derived Schiff base ligands has been synthesized and applied to titanium catalyzed hetero-Diels-Alder reaction of Danigheifsky‘ s diene and aldehydes, affording the corresponding 2-substituted 2,3-dihydro-4H-pyran-4-one in good yields and moderate enantioselectivities (up to 59.2% ee). It was found that the size of dendron attached to the tridentated ligands has slight impact on the enantioselectivtty of the reaction and the second generation of dendritic ligand exhibited the best enantioselectivity.     

Synthesis of Peptoid Nucleic Acid with Thymine as Nucleic Base

The sequence specific bonding of oligonucleotide to RNA or double stranded DNA hasattTacted wide attention as the antisense and antigene strategies for treatment of diseasesat the level of gene expression in medicinal chemistry'. Peptide nucleic acids designedas a chemira of nucleobases and polyamidic backbone bind with high affinity andsequence specifity to both comPlementary RNA and DNA and a number of templatefunctions are inhibited on forming PNAasA and PNA/DNA complex'-'. In the …     

Reaction of Methyl Vinyl Sulfone with Schiff Bases Derived from α-Alanine Methyl Ester and Aromatic Aldehydes

Russian Journal of Organic Chemistry - Schiff bases derived from α-alanine methyl ester and aromatic aldehydes reacted with methyl vinyl sulfone in toluene at 20°C in the presence of...     

Threshold dynamics of a stochastic Keizer’s model with stochastic incidence

In this paper, we incorporate stochastic incidence of a chemical reaction into the standard Keizer’s open chemical reaction. We prove that a positive stationary distribution (PSD) for the associated chemical master equation exists and is globally asymptotically stable. We present threshold dynamics of the stochastic Keizer’s model in term of the profile of the PSD for both finite and infinite volume size V. This establishes a sharp link between deterministic Keizer’s model and the stochastic model. In this way, we resolve Keizer’s paradox from a new perspective. This simple model reveals that such stochastic incidence incorporated, though negligible when V goes to infinity, may play an indispensable role in the stochastic formulation for irreversible biochemical reactions.     

Concise synthesis of xanthones by the tandem etherification——Acylation of diaryliodonium salts with salicylates

An efficient synthetic method for multi-substituted xanthones was developed. The reaction of diaryliodonium salts and salicylates was employed for the preparation of the xanthones. This method proceeded through an intermolecular etherification-acylation to give target heterocycle in good yields (up to 91%). Multi-substituted xanthones were gained by shifting the substituent of salicylates or diaryliodonium salts.     

Comparison of hydrophobicity studies of silica aerogels using contact angle measurements with water drop method and adsorbed water content measurements made by Karl Fischer’s titration method

Hydrophobic silica aerogels possesses potential applications as insulating materials for refrigerators, furnaces and thermos flasks. In such applications, aerogel materials may get exposed for longer time to atmosphere and the adsorbed water content from surroundings may deteriorate its properties. Therefore, hydrophobicity of the arogels becomes crucial parameter and needs to be evaluated critically. In the present works, silica alcogels were prepared using the mixture of tetramethoxysilane and methyltrimethoxysilane (MTMS) as precursor chemicals for silica. The concentration of MTMS, which is used as hydrophobic reagent, in the said mixture of silicon alkoxide was varied between 0 and 100% in steps of 25%. After gelation, the alcogels were dried supercritically by solvent extraction method. Resulted aerogels were exposed to relative humidity of 90% for a period of one month which were then characterized to assess hydrophobicity by the contact angle using water drop method and adsorbed water content measurements by Karl Fischer’s Titration method. Observed contact angle and water content measurements were compared and the results are reported in the present research paper.     

Catalytic Acylation of Ethylidenecyclohexane over Zeolite Catalysts

Beak et al[1 ] reported that the acylation of ethylidenecyclohexane( EDC) using zincchloride as a catalyst gave 3 -( 1 -cyclohexenyl) -2 -butanone( CHB) in good yield.However,it is pity that they provided only little information about reaction conditions,and no information on comparison of activities of various catalysts. Itis well known thatconventional Zn Cl2 catalyst leads to a great number of environmental pollution,whichcould be mainly overcome by use of the solid catalysts as we have …     

One Novel Red-luminescent Coordination Polymer of Eu-p-benzenedicarboxylate with Nitrogen-donor-containing Lewis Base

The crystal structure of novel coordination polymer with excellent characteristic luminescence of Eu^3 ,the three-dimentional network of {Eu2(p-BDC)3(Phen)2(H2O)2}n is presented.     

Synthesis and Transesterification of the Complexes of Methyl 2-Methyl-3-trichlorostannylpropoinate with Benzylmethylsulfoxide

2-Methyl-3-trichlorostannylpropionate, Cl3SnCH2CH(CH3)CO2R, a novel type of mono- organotin compounds containing ester group, have received considerable attention since Hutton et al. reported their synthesis because of the variety of coordination geometry about tin atom1-4. Organotin compounds5 like organotin carboxylates or oxides were already used as transesterification catalysts, however, little attention was paid to transestrifications of 2-methyl-3-trichlorostannylpropionate complexe…