- Quantum Yields in the Photochemically Induced Radical Chemistry of Acyl Derivatives of Thiohydroxamic Acids
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Acyl derivatives of N-hydroxyquinazoline-4-thiones are a novel source of disciplined carbon radicals.Quantum yield determination reveals that photolysis of these compounds initiates radical chains, resulting in quantum yields up to φ = 60.Comparative studies with acyl derivatives of N-hydroxy-2-thiopyridone show that the quinazoline derivatives are more light-sensitive than the thiopyridone compounds.The carbon radicals thus formed from the former can be trapped selectively, without the formation of rearranged products (i.e. without the competition of the radicophilic thiocarbonyl group of the starting material with the radical trap).
- Barton, Derek H. R.,Blundell, Paul,Jaszberenyi, Joseph Cs.
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p. 6937 - 6942
(2007/10/02)
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- Sonication-Induced Halogenative Decarboxylation of Thiohydroxamic Esters
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The sonication of primary, secondary, and tertiary thiohydroxamic esters in CCl4 has led to their synthetic transformation to alkyl chlorides, bromides, or iodides.The high yields were comparable to the previous thermal-or photoinduced version of this same reaction.This radical reaction calls attention to the utility of ultrasound in production of trichloromethyl radical, which was concluded to initiate decomposition of the thiohydroxamic esters.
- Dauben, William G.,Bridon, Dominique P.,Kowalczyk, Bruce A.
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p. 6101 - 6106
(2007/10/02)
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- Photochemical Chlorodecarboxylation via an Electron Transfer Mechanism
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A new method of chlorodecarboxylation of carboxylic acids via N-acyloxyphthalimides is developed; the reaction proceeds upon irradiation of N-acyloxyphthalimides in the presence of 1,4-diazabicyclooctane in ButOH-CCl4-H2O (53:42:5 v/v) in moderate to high yields.
- Okada, Keiji,Okamoto, Kazushige,Oda, Masaji
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p. 1636 - 1637
(2007/10/02)
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- LIGHT INDUCED HALOGENATIVE DECARBOXYLATION OF THIOHYDROXAMIC ESTERS
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The generality of lidht initiated halogenative decarboxylation of thiohydroxamic esters was studied.This method gave high yields of alkyl chlorides, bromides and iodides derived from primary, secondary and tertiairy substituted carboxylic acids.
- Dauben, William G.,Kowalczyk, Bruce A.,Bridon, Dominique P.
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p. 2461 - 2464
(2007/10/02)
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- HOMOLOGATION DES DERIVES HALOGENES
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The halide R-X is converted, in two steps, to its homologous R-CH2-X.
- Yankep, Emmanuel,Charles, Georges
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p. 427 - 430
(2007/10/02)
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- The Invention of New Radical Chain Reactions. Part 9. Further Radical Chemistry of Thiohydroxamic Esters; Formation of Carbon-Carbon Bonds
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Carbon radicals derived from the esters of several types of thiohydroxamic acids have been trapped in a number of different ways.Particular attention has been paid to carbon-carbon bond formation by addition to suitably activated ethylenic linkages.Carboxylic acids can be conveniently converted into homo- and bishomo-acids by free radical chemistry based on thiohydroxamic esters.In a coda the tautomerism of the thiohydroxamic acids have been examined by physical methods.It is confirmed that the esters used are derivatives of the thione tautomer.
- Barton, Derek H.R.,Crich, David,Kretzschmar, Gerhard
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- THE INVENTION OF NEW RADICAL CHAIN REACTIONS. PART VIII. RADICAL CHEMISTRY OF THIOHYDROXAMIC ESTERS; A NEW METHOD FOR THE GENERATION OF CARBON RADICALS FROM CARBOXYLIC ACIDS.
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The aliphatic and alicyclic esters of N-hydroxy-pyridine-2-thione are readily reduced by tributylstannane in a radical chain reaction to furnish nor-alkanes.In the absence of the stannane a smooth decarboxylative rearrangement occurs to give 2-substituted thiopyridines.The radicals present in this reaction provoke with t-butylthiol an efficient radical reaction with formation of nor-alkane and 2-pyridyl-t-butyl disulphide.Similarly these carbon radicals can be captured by halogen atom transfer to give noralkyl chlorides, bromides and iodides.With oxygen in the presence of t-butylthiol the corresponding noralkyl hydroperoxides are formed in another radical chain reaction.
- Barton, Derek H. R.,Crich, David,Motherwell, William B.
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p. 3901 - 3924
(2007/10/02)
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- RADICAL CHEMISTRY OF THIOHYDROXAMIC ACID ESTERS
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Thiohydroxamic esters in general decompose smoothly by a radical chain reaction to give carbon radicals which can be quenched in a synthetically useful manner.
- Barton, Derek H. R.,Kretzschmar, Gerhard
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p. 5889 - 5892
(2007/10/02)
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- A PRACTICAL ALTERNATIVE TO THE HUNSDIECKER REACTION
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Carboxylic acid esters derived from N-hydroxy-pyridine-2-thione react with carbon tetrachloride, bromotrichloromethane or iodoform in a radical chain reaction to give the corresponding noralkyl chlorides, bromides or iodides in high yield.
- Barton, Derek H.R.,Crich, David,Motherwell, William B.
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p. 4979 - 4982
(2007/10/02)
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