Use of tris (pentafluorophenyl) bismuth as an arylating reagent

It has been shown that tris(pentafluorophenyl)bismuth arylates polyfluorinated electrophilic compounds in the presence of cesium fluoride.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 171–172, January, 1994.     

Palladium-catalyzed oxidative arylating carbocyclization of allenynes

Vinylallenes or cross-conjugated trienes are obtained selectively in the title reaction. Two possible mechanisms are suggested to rationalize the formation of the different types of products. Control experiments indicate that p-benzoquinone (BQ) plays an important role as a ligand in addition to its role as an oxidant. E=CO(2)Me.     

Synthesis of N-substituted acrylamides

Summary The following compounds have been obtained and characterized for the first time:O-,m-, andp-ethoxyphenyl-acrylamides and N -methyl-o-, -m- and -p-N-ethoxphenylacrylamides.     

Reactivity studies of S-methylthiophenium tetrafluoroborates

The polarographic behavior of four S-methylthiophenium tetrafluoroborates, I-IV, has been investigated in Britton-Robinson aqueous buffers. The compounds under study were the S-methylbenzo[b]thiophenium (I), S-methylnaphtho[2,3-b]thiophenium (II), S-methyldibenzothiophenium (III), and S-methylnaphtho[2,1-b]thiophenium (IV) tetrafluoroborates which were obtained from the parent sulfur heterocycles by their reaction with methyl iodide and silver tetrafluoroborate in 1,2-dichloroethane, II and IV being new compounds. Compounds I-IV give two one-electron reduction waves and the more positive wave appears to be associated with an electron transfer from the electrode to the LUMO of the substrate as indicated by the experimental E_1/2 vs calculated LUMO values plot (Figure 2). The rates of demethylation of the ions I-IV with the iodide ion acting as the nucleophile have been determined in the Britton-Robinson buffer (pH 6)-acetonitrile solution at 24°. The results of the polarographic study and of the kinetic studies with the iodide ion confirm the high reactivity of S-methylthiophenium ions which originates in the antiaromatic destabilization of these structures.     

Synthesis of 2,6-diarylpyrylium tetrafluoroborates

A number of previously unknown 2,6-diarylpyrylium tetrafluoroborates was obtained by the reaction of substituted acetophenones with ethyl orthoformate and boron trifluoride etherate.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1168–1169, September, 1982.     

First asymmetric aminohydroxylation of acrylamides

The first examples of the asymmetric aminohydroxylation of acryl amides are reported. This was accomplished with chiral acrylamides as substrates, which undergo diastereoselective oxidative transformation within the so-called ‘second catalytic cycle’ with diastereomeric excesses reaching 100:0. The reaction relies solely on the stereochemical information provided by the enantiomerically pure starting materials. A stereochemical model for the observed asymmetric induction is provided.     

Radical polymerization of n-substituted methacrylamides

The relationship between the structure of monomer and kinetics of the radical polymerization of N-ethylmethacrylamide, N-butylmethacrylamide and N-phenylmethacrylamide in methanol and in dimethylsulphoxide was investigated. The reaction order with respect to initiator is 0·5 in all cases; the order with respect to monomer is independent of the type of substituent but depends on the solvent and on the viscosity of the reaction mixture. The polymerization rate, the value of $\text{κ}{}_{\mathrm{p}}\text{/κ}{}_{\mathrm{t}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, and the initiator efficiency decrease in the series N-phenylmethacrylamide, N-ethylmethacrylamide and N-butylmethacrylamide. The overall activation energy of polymerization for the monomers lies between 16 and 20 kcal/mol.     

Copolymerizations of 2-hydroxyethylmethacrylate with vinylpyridines and with N-substituted methacrylamides

Studies were made of the copolymerizations of 2-hydroxyethylmethacrylate with 2-, 3- and 4-vinylpyridine. N-(trans-4′-nitro-4-stilbenyl)methacrylamide and N-(trans-4-stilbenyl)methacrylamide. Methods of Fineman-Ross, Joshi-Joshi, Tidwell-Mortimer and Tosi were employed to determine monomer reactivity ratios; the results for 2- and 4-vinylpyridine were compared with those calculated from the Q-e scheme. The monomer reactivity ratios for 2-hydroxyethylmethacrylate with vinylpyridines calculated by different methods showed good agreement. The monomer reactivity is briefly discussed.     

Synthesis and spectral-luminescence properties of 2,7-diaminobenzopyrylium tetrafluoroborates

Stable 2,7-diaminobenzopyrylium tetrafluoroborates were obtained by the successive treatment of 7-diethylaminocoumarin, 4-methyl-7-diethylaminocoumarin, and 9-methyl-1H,5H-quinolizino[9,9a,1-gh]coumarin with triethyloxonium tetrafluoroborate and amines, viz., diethylamine, piperidine, morpholine, benzylamine, and aniline. The spectral-luminescence characteristics of the synthesized compounds were investigated. The data from the ¹³C NMR spectra and x-ray diffraction analysis confirm the greater participation of the 2-amino group as compared with the 7-amino group in stabilization of the positive charge of the pyrylium system.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 755–766, June, 1989.     

Nickel-catalyzed synthesis of acrylamides from alpha-olefins and isocyanates

[reaction: see text] The nickel(0)-catalyzed coupling of alpha-olefins and isocyanates proceeds in the presence of the N-heterocyclic carbene ligand IPr to provide alpha,beta-unsaturated amides. Carbon-carbon bond formation occurs preferentially at the 2-position of the olefin. The N-tert-butyl amide products can be converted to the corresponding primary amides under acidic conditions.     

4-Alkoxycarbonyl- and aminocarbonyl-substituted isoxazoles as masked acrylates and acrylamides in the asymmetric synthesis of delta2-isoxazolines

4-Alkoxycarbonyl and aminocarbonyl-substituted isoxazoles undergo conjugate reduction to give delta2-isoxazolines on treatment with sodium borohydride and sodium trifluoroacetoxyborohydride, respectively. They are also alkylated at C5 through sonication with secondary and tertiary alkyl iodides in the presence of zinc dust and copper(I) iodide. These reactions are analogous to those observed with acrylates and acrylamides. The behavior is characteristic of the 4-substituted isoxazoles but not the 5-substituted regioisomers. The reductions of 4,5-disubstituted isoxazoles and the C5 alkylations of 4-substituted isoxazoles generally afford trans-4,5-disubstituted isoxazolines. Incorporating chiral auxiliaries into the alkoxycarbonyl group maintains this relative stereoselectivity. It does not provide significant levels of asymmetric induction in the reductions, but the alkylations occur with good levels of stereocontrol at both C4 and C5. Because both enantiomers of the auxiliaries are available, this provides access to either enantiomer of the products, in 93 to > or = 98% de. The methodology, therefore, provides a complementary approach to nitrile oxide cycloadditions to alkenes for the asymmetric synthesis of delta2-isoxazolines.     

CNDO calculations of N-methyl substituted acrylamides

CNDO calculation is made for N-methyl acrylamide (both incis andtrans configurations) and N,N-dimethyl acrylamide. The charges, bond orders and dipole moments are discussed and compared with those of acrylamide. Thetrans form of N-methyl acrylamide is found to be more stable thancis isomer by 4.5 kcal/mole.     

Ruthenium-catalyzed carbonylation of allene: direct synthesis of methacrylates and methacrylamides

Carbonylation reactions of allene in alcohols and amines in the presence of a ruthenium carbonyl catalyst under mild conditions gave methacrylates and methacrylamides, respectively, in good yields with an atom economy of 100%.     

Phase transfer catalyzed synthesis of indazoles from o-alkylbenzenediazonium tetrafluoroborates

Reactions of o-methyl- and o-ethylbenzenediazonium tetrafluoroborates with two equivalents of potassium acetate and five mole percent of 18-crown-6 in ethanol-free chloroform produce indazoles in good to excellent yields. Indazoles bearing either electron-withdrawing or electron-donating substituents may be prepared.