- An alternative approach to differentially substituted 2-oxazoline chalcogen derivatives
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In this study we present an alternative method to obtain several substituted mono or bis-2-oxazolines containing a chalcogen atom as a tether element. Alkylation of 2-tosyloximethylene-2-oxazoline with an appropriate sodium, lithium or potassium alkoxide yielded the corresponding ether. Introduction of sulfur or selenium was easily accomplished using the corresponding sodium salts. The 77Se NMR for alkyl or aryl 2-methylene-2-oxazoline selenides shows good correlation with the electronegativity pattern of substituents. Most products containing oxazolinyl-chalcogen were stable under the usual experimental conditions. However, the tellurium derivatives showed unusual sensitivity to light and oxygen, decomposing through a very complex mechanistic pathway. As a result of this oxidative process, 4,4-dimethyl-2-oxazoline-2-carbaldehyde could be isolated and fully characterized for the first time, in 17% yield.
- De Mello, Murilo B.M.,Clososki, Giuliano C.,Piovan, Leandro,De Oliveira, Alfredo R.M.
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- Condensed oxaziridine-mediated [3+2] cycloaddition: Synthesis of polyhetero-bicyclo compounds
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Polyhetero-bicyclo compounds were synthesized by a regioselective [3+2]-cycloaddition reaction between stable condensed oxaziridines and alkenes, alkynes, and nitriles. These molecules showed considerable antimicrobial activity against several gram-positive bacteria.
- Videtta, Valeria,Perrone, Serena,Rosato, Francesca,Alifano, Pietro,Tredici, Salvatore M.,Troisi, Luigino
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scheme or table
p. 2781 - 2783
(2010/12/25)
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- Generation of cyclic ketene-N,X-acetals (X = O, S) from 2-alkyl-1,3-oxazolines and 2-alkyl-1,3-thiazolines. Reactions with acid chlorides, 1,3-diacid chlorides and N-(chlorocarbonyl) isocyanate
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2-Alkyl-1,3-oxazolines, 2-alkyl-1,3-thiazolines, and the corresponding cyclic ketene-N,X-acetals (X = O, S) derived from them were reacted with monoacid chlorides, diacid chlorides, triacid chlorides. A series of these carbon-carbon bond-forming reactions and cyclizations to both substituted 2,3-dihydrooxazolo[3,2-a]pyridine-5,7-diones and 2,3-dihydrothiazolo[3,2-a] pyridine-5,7-diones proceeded under mild reaction conditions. Cyclic ketene-N,X-acetal intermediates play important roles in all these reactions. Related cyclizations with N-(chlorocarbonyl) isocyanate formed substituted 2,3-dihydrooxazolo[3,2-c]pyrimidine-5,7-diones and 2,3-dihydrothiazolo[3,2-c] pyrimidine-5,7-diones. Georg Thieme Verlag Stuttgart.
- Zhou, Aihua,Pittman Jr., Charles U.
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- Chemical C2-elongation of polyunsaturated fatty acids
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Three fatty acids were synthesized from commercially available α-linolenic, stearidonic and eicosapentaenoic acids by C2-elongation using a four step preparative technique. The parent fatty acid methyl esters were reduced to alcohols with LiAlH4, converted to bromides by treatment with triphenylphosphine dibromide, coupled with a lithiated C2-elongation block - 2,4,4-trimethyl-2-oxazoline - to form the corresponding 2,2-dimethyloxazolines of C2-elongated fatty acids, and finally, converted to the target polyunsaturated fatty acids by acidic alcoholysis. Yields of more than 60% were achieved on a gram scale. The resulting 11Z,14Z,17Z-eicosatrienoic, 8Z,11Z,14Z,17Z-eicosatetraenoic and 7Z,10Z,13Z,16Z,19Z-docosapentaenoic acids were obtained as colorless oils with >98% purity and could be used for biochemical investigations without additional purification. The elongated fatty acids were free of byproducts that could result from Z-E isomerization or migration of double bonds.
- Kuklev, Dmitry V.,Smith, William L.
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p. 172 - 177
(2007/10/03)
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- Decomposition of alkene adducts of thianthrene cation radical in nitrile solvents. Formation of alkyl-2-oxazolines and a new class of four-component products: 5-[(1-alkoxyalkylidene) ammonio]alkylthianthrenium diperchlorates
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The monoadducts (4a-d) of thianthrene cation radical perchlorate (1a) and isobutene, 2-methyl-butene, 2-methyl-2-butene, and 2-methylpentene decompose spontaneously in acetonitrile (MeCN) solution, with the formation of thianthrene (Th). Decomposition of 4a (1,2-(5,10-thianthreniumdiyl)-2-methylpropane diperchlorate) and 4a', the corresponding dihexafluorophosphate, was studied in depth and extensively with 1H and 13C NMR spectroscopy. Decomposition of 4a was found to involve the solvent itself as well as water in the solvent, remaining from incomplete drying, and gave, apart from Th, successively, the perchlorate salts of 2,4,4-trimethyl-2-oxazoline (6) and 2-amino-2-methylpropyl acetate (7). These salts, 6-HCIO4 and 7-HCIO4, respectively, were prepared and used in understanding the reactions of 4a as well as the relationships among 6, 7, and 2-(acetylamino)-2-methyl propanol (8) in acidified MeCN solution. Decompositions of 4a-d in MeCN and other nitriles (RCN) containing an added alcohol (ROH) led to new products, 5-[(1-alkoxyalkylidene)ammonio]alkylthianthrenium diperchlorates (5a-u). These compounds were identified with 1H and 13C NMR spectroscopy and, in part, with X-ray crystallography and elemental analysis. The mechanisms of formation of 5-7 are discussed.
- Shine, Henry J.,Zhao, Bing-Jun,Marx, John N.,Ould-Ely, Teyeb,Whitmire, Kenton H.
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p. 9255 - 9261
(2007/10/03)
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- Manufacture of 2-oxazolines, 2-oxazines, 2-imidazolines and 2-imidazines
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A process for the production of a product selected from the group consisting of a 2-oxazoline or a 2-oxazine and a 2-imidazoline or a 2-imidazine comprising reacting a bicyclic amide acetal with a member selected from the group consisting of an alkanol amine and an alkylene polyamine, respectively, at a temperature in the range of from about 20° C. to 200° C. is described.
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- SYNTHESIS OF ISOTHIOCYANATES FROM NON-AROMATIC NITROGEN-CONTAINING HETEROCYCLES
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Investigation of the reaction of thiophosgene with Δ2-oxazolines I, Δ3-thiazolines II, 4H-benzothiazines III, 2-methoxypentahydro-Δ1-azepine IV, theophylline and caffeine showed that only compounds I and IV reacted to give 2-acyloxyethyl isothiocyanates and methyl 6-isothiocyanatohexanoate.The structure of these products was corroborated by IR, 1H NMR, 13C NMR and mass spectral methods.The suitability of the above-mentioned compounds to react is discussed.
- Gonda, Jozef,Kristian, Pavol,Mikler, Lubomir
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p. 112 - 117
(2007/10/02)
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- The Chemistry of Nitrilium Salts. Part 2. The Preparation of Nitrilium Trifluoromethanesulphonate Salts and Their Reactions with Some Oxygen and Sulphur Nucleophiles
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The syntheses of the nitrilium salts NMe>+3SCF3 i, PhCH2, Ph, CH2=CHCH2, NC(CH2)3, and CH2=CH> by reaction of MeO3SCF3 with the corresponding nitriles are described. the similar reaction between (E)-PhCH=CHCN and MeO3SCF3 gives a mixture of NMe>+SCF3 and the s-triazinium salt 3C3N3H>+3SCF3, which hydrolyzes to give (E)-PhCH=CHCONHMe and the triazine.The compound CF3SO3(CH2)4CN, prepared from I(CH2)4CN and AgO3SCF3, does not form a cyclic nitrilium salt, but slowly dimerizes at room temperature to N(CH2)4CN>+3SCF3.Both I(CH2)4CN and CF3SO3(CH2)4CN can be converted into the salt NMe>+3SCF3, but this does not form a dinitrilium salt on reaction with acetonitrile.On heating benzophenone oxime with CF3SO3H Beckmann rearrangement products are obtained, but conversion of +SCF3 into the nitrilium salt NPh>*3SCF3 ocuurs in only low yield even after 8 h at 130 deg C under high vacuum.The nitrilium salts with R = Ph, Me, Pri, and PhCH2 undergo rapid exothermic reaction with phenol, thiophenol, alcohols, and thiols to give the corresponding imidate and thioimidate salts in high yields. 4,4-Dimethy-2-phenyl-1,3-oxazoline is obtained in 74percent yield on heating NMe>+*3SCF3 with H2NCMe2CH2OH, and both this and 2,4,4-trimethyloxazoline react with MeO3SCF3 to give almoust quantitative yields of the corresponding N-methyloxazolinium salts, which can be reduced to the oxazolidines with NaBH4.N-Methyloxazolinium salts have also been obtained from the reactions of nitrilium salts (R = Ph or Me) with ethylene oxide.
- Booth, Brian L.,Jibodu, Kehinde O.,Proenca, M. Fernanda J. R. P.
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p. 1067 - 1073
(2007/10/02)
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