Synthesis of 3-aryl-5-dichloromethyl-1H-pyrazole-1-carboxamides from 1-aryl-3,4,4-trichlorobut-3-en-1-ones

The reaction of 1-aryl-3,4,4-trichlorobut-3-en-1-ones with semicarbazide hydrochloride in the presence of sodium acetate is accompanied by prototropic allylic rearrangement, leading to the formation of two isomeric products, semicarbazones of the initial ketones and 1-aryl-3,4,4-trichlorobut-2-en-1-one semicarbazones. The latter undergo heterocyclization in the presence of triethylamine to give the corresponding 3-aryl-5-dichloromethyl-1H-pyrazole-1-carboxamides.     

Mechanism of ring opening of cis- and trans-1-methyl-2-aryl-3-aroylaziridine perchlorates under the influence of alcohols

The corresponding threo- and erythro-1,3-diaryl-3-alkoxy-2-N-methylamino-1-propanones, which are formed regio- and stereospecifically, were obtained by the reaction of cis- and trans-1-methyl-2-aryl-3-aroylaziridine perchlorates with alcohols.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1054–1058, August, 1989.     

A convenient ring formation of 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans from phenols and 2-aryl-2,2-dialkylacetaldehydes

A new and simple route for the preparation of 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans from phenols is described. In the presence of an acid catalyst phenols react with 2-aryl-2,2-dialkylacetaldehydes, prepared in good yield from 2-arylacetonitriles in 2 steps, to give 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans. Electron-donating substituents were required on the phenols in order to give 3-aryl-2,2-dialkyl-2,3-dihydrobenzofurans in good yield.     

Thermoanalytical study of nimesulide and their recrystallization products obtained from solutions of several alcohols

Thermogravimetry, differential scanning calorimetry, and vibrational infrared spectroscopy were used to study nimesulide and its recrystallization products that were obtained from solutions of several alcohols. The thermoanalytical measurements were performed in both air and nitrogen atmospheres and the results suggest that, under the experimental conditions used in this paper, it was possible to obtain neither polymorphic nor pseudopolymorphic forms of this drug. In this investigation, quantum chemical approach methods were used to determine the molecular structures using the Becke three-parameter hybrid method and the Lee–Yang–Parr correlation functional. The performed molecular calculations were done with the Gaussian 09 routine and the theoretical calculation results were correlated with the experimental IR vibrational spectrum.     

Iodine/Et3SiH: a novel reagent system for the synthesis of 3-aryl-1H-indenes from 1,3-diaryl propargyl alcohols

1,3-Diaryl propargyl alcohols undergo smooth intramolecular Friedel-Crafts cyclization with triethylsilane in the presence of 10 mol % iodine 3-aryl-1H-indene derivatives in good yields in short reaction times. This is the first example on the synthesis of substituted indenes from 1,3-diaryl propargyl alcohols. The use of inexpensive and readily available molecular iodine makes this method quite simple, more convenient, and practical.     

Stereoselective synthesis of chiral 3-aryl-1-alkynes from bromoallenes and heterocuprates

The synthesis of chiral 3-aryl-1-alkynes 3 via cross-coupling of 3-alkyl- and 3,3-dialkyl-1-bromo-1,2-dienes 1 and arylbromocuprates (RCuBr)MgBr.LiBr 2 was examined. With phenylcopper reagents and its para-substituted derivatives, as well as with 2-naphthyl cuprates, the reaction gave compounds 3 with high regioselectivity and good yields on the chemically pure product. On the contrary, when ortho-substituted phenyl reagents and 1-naphthyl cuprates were used, the regioselectivity of the process was very dependent upon the steric requirements of the alkyl substituents on the bromoallenic substrate. When the steric bulk was increased, remarkable quantities of isomeric arylallenes 4 were also observed in the reaction mixtures. The high 1,3-anti stereoselectivity of the coupling process allowed us to obtain enantiomerically enriched 3-aryl-1-alkynes from optically active allenic substrates, thus indicating a simple pathway toward the synthesis of quaternary stereogenic centers characterized by an aryl group. A possible cross-coupling mechanism was also suggested to explain the regio- and stereochemical data. For the preparation of omega-functionalized 3-phenyl-1-alkynes, the reaction of 1-bromo-3-phenylpropadiene with Knochel reagents RCu(CN)ZnCl.2LiCl was also studied; this reaction led to the acetylenic compounds in high yields mainly when the R group (also omega-functionalized) on the copper reagent was primary.     

1-Benzoyl-2-aryl-3-arylmethyl-1,3-diazacyclanes — New products of the acylation of bis-azomethines

Conclusion The benzoylation of bis-azomethines derived from ethylenediamine and cis-1,3-diaminocyclohexane gives 1,3-dibenzoyl-1,3-diazacyclanes and 1-benzoyl-3-benzyl-1,3-diazacyclanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1132–1134, May, 1987.     

Enhanced stability and bioconjugation of photo-cross-linked polystyrene-shell, Au-core nanoparticles

Encapsulating Au nanoparticles within a shell of photo-cross-linked block copolymer surfactant dramatically improves the physical and chemical stability of the nanoparticles, particularly when they are applied as bioconjugates. Photo-cross-linkable block copolymer amphiphiles [polystyrene-co-poly(4-vinyl benzophenone)]-block-poly(acrylic acid) [(PS-co-PVBP)-b-PAA] and [poly(styrene)-co-poly(4-vinyl benzophenone)]-block-poly(ethylene oxide) [(PS-co-PVBP)-b-PEO] were assembled around Au nanoparticles ranging from 12 to 108 nm in diameter. UV irradiation cross-linked the PVBP groups on the polymer to yield particles that withstood extremes of temperature, ionic strength, and chemical etching. Streptavidin was attached to [PS-co-PVBP]-b-PAA-coated particles using the same noncovalent and covalent conjugation protocols used to bind biomolecules to divinylbenzene-cross-linked PS microspheres. We expect that these particles will be useful as plasmonic, highly light-scattering and light-absorbing analogs to fluorescently labeled PS nanospheres.     

Study of radical products in branched polyhydric alcohols

Conclusions The EPR method was used to study the radicals in --irradiated pentaerythritol, metriol, etriol, and trimethylolisobutane, and it was shown that the probability of cleaving the C-H bond in it increases with increase in the chain length of the alkyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 466–468, February, 1976.     

Thermo-, photo-, and chemo-responsive shape-memory properties from photo-cross-linked metallo-supramolecular polymers

Films exhibiting multiresponsive shape-memory properties have been accessed using covalently cross-linked metallo-supramolecular polymers. Low molecular weight poly(butadiene) was end-capped with 4-oxy-2,6-bis(N-methylbenzimidazolyl)pyridine (-OMebip) ligands that upon addition of metal salts spontaneously formed high molecular weight metallo-supramolecular polymers. The addition of a tetra-functional thiol along with a photoinitiator results in mechanically stable films via solution-casting. These films consist of a soft poly(butadiene) phase and a hard metal-ligand phase. Photo-cross-linking of the poly(butadiene) soft phase, via the thiol-ene reaction, upon exposure to relatively low intensity light, allows access to a diverse range of permanent shapes. Investigations into the temporary shape fixing and recovery of these materials were undertaken to determine the effects of cross-link density and the nature of the metal salts. The key component in fixing and releasing the temporary shape is the metal-ligand hard phase, and as such any stimulus that can disrupt this phase (light, heat, or chemicals) can be used to create the temporary shape and induce its recovery back to the permanent shape.     

Aminomethylation of 3-aryl-7-hydroxycoumarins

The reaction of the analogs of natural 3-arylbenzopyran-2-ones with electrophilic reagents of aminal structure was studied. Substituted 8-aminomethyl-3-aryl-7-hydroxycoumarins were synthesized. The optimum conditions were determined for the production of 9-alkyl- and 9-(het)arylmethyl derivatives of 3-aryl-9,10-dihydro-2H,8H-chromeno[8,7-e][1,3]oxazin-2-one in the series of analogs of natural 3-arylbenzopyran-2-ones.     

Chemistry of 2-aryl-3-pyridinols

Russian Chemical Bulletin -     

Preparation of 3-aryl-2-quinoxalones

Arenesulfonamides are split out in the reaction of N-(arylsulfonyl)arylglyoxylamides with o-phenylenediamine to give 3-aryl-2-quinoxalones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 819–820, June, 1977.     

Synthesis of 3-aryl-4-isothiazolecarboxylates

A short, convenient route to 3-aryl-4-isothiazolecarboxylates is described in which aryl Grig-nard reagents are added to the magnesium etiolate of ethyl cyanoacetete, and the resultant β-aminocinnamates are converted via a Vilsmeier-Haack reaction, thiation, and oxidation to the isothiazolecarboxylates.     

Synthesis of 2-aryl-3-trifluoromethylsulfonylpyrroles

A general method for the preparation of 2-aryl-3-trifluoromethylsulfonylpyrroles 2 has been developed. Procedures for the construction of the key enamine intermediates 9 and their cyclizations to pyrroles are reported.