- Radical OfC transposition: A metal-free process for conversion of phenols into benzoates and benzamides
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We report a metal-free procedure for transformation of phenols into esters and amides of benzoic acids via a new radical cascade. Diaryl thiocarbonates and thiocarbamates, available in a single high-yielding step from phenols, selectively add silyl radicals at the sulfur atom of the CdS moiety. This addition step, analogous to the first step of the Barton-McCombie reaction, produces a carbon radical which undergoes 1,2 OfC transposition through an O-neophyl rearrangement. The usually unfavorable equilibrium in the reversible rearrangement step is shifted forward via a highly exothermic C-S bond scission in the O-centered radical, which furnishes the final benzoic ester or benzamide product. The metal-free preparation of benzoic acid derivatives from phenols provides a potentially useful alternative to metal-catalyzed carbonylation of aryl triflates.
- Baroudi, Abdulkader,Alicea, Jeremiah,Flack, Phillip,Kirincich, Jason,Alabugin, Igor V.
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experimental part
p. 1521 - 1537
(2011/06/11)
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- Aminolysis of aryl chlorothionoformates with anilines in acetonitrile: Effects of amine nature and solvent on the mechanism
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The aminolysis of aryl chlorothionoformates (7, YC6H 4OC(=S)Cl) with anilines (XC6H4NH2) in acetonitrile at 5.0 °C has been investigated. The rates are slower than those for the corresponding reactions of aryl chloroformates (6, YC 6H4OC(=O)Cl). This rate sequence is a reverse of that for alkyl chloroformates (1 4) in water, for which rate-limiting formation of a tetrahedral intermediate, T±, is predicted. On the basis of the large negative cross-interaction constant, ρXY = -0.77, failure of the reactivity-selectivity principle, normal kH/k D values involving deuterated nucleophiles (XC6H 4ND2), and low ΔH≠ with large negative ΔS≠ values, a concerted mechanism with a four-membered hydrogen bonded cyclic transition state (11) is proposed for the title reaction series. It has been shown that the solvent change from water to acetonitrile for the aminolysis of 6 and 7 causes a mechanistic change from stepwise to concerted.
- Oh, Hyuck Keun,Ha, Joo Suk,Sung, Dae Dong,Lee, Ikchoon
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p. 8219 - 8223
(2007/10/03)
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- Episulfidation of strained cycloalkenes in the thermolysis of 5-aryloxy-1,2,3,4-thiatriazoles
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The thermolysis of 5-aryloxythiatriazoles 1 in the presence of norbornene (2a) and trans-cyclooctene (trans-2b) affords the corresponding thiiranes 3a and trans-3b in moderate yields. First-order kinetics are observed, suggesting that a sulfur intermediate, presumably dinitrogen sulfide, is generated in the fragmentation process of 1, which then serves as the active sulfur atom donor.
- Adam, Waldemar,Bargon
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p. 1959 - 1962
(2007/10/03)
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- NITROXIDE CHEMISTRY XXI. REACTIONS OF BIS(BISTRIFLUOROMETHYLAMINO-OXY)-MERCURY(II) AND NN-BIS(TRIFLUOROMETHYL)NITROXIDE WITH THIOCARBONYL COMPOUNDS
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Thiobenzophenone, 9-thiocarbonylfluorene and carbonyl sulphide react with the mercurial, Hg2, to form HgS and the compounds Ph2C2, (C6H4)2C2 and 2CO respectively.The last compound is also formed as the major product on mixing the mercurial with carbon disulphide.With thiophosgene, reaction occurs to form HgCl2 and a mixture of the compounds (CF3)2NSCOCl and (CF3)2NSCOON(CF3)2, which are thought to arise by rearrangement of the intermediates (CF3)2NOC(S)Cl and 2CS.A similar rearrangement may also occur during the reactions of thiobenzoyl chloride and aryl chlorothionoformates with the mercurial but the product mixtures from these reactions are more complex and pure compounds have not been isolated.Reaction between thiophosgene dimer and the mercurial results in a simple chlorine exchange to afford the 1,3-dithietane 2cyclo2S>.The low temperature reaction of thiophosgene with (CF3)2NO gives a thermally unstable product believed to be (CF3)2NOCCl2S(O)ON(CF3)2, while the similar reaction with thiobenzophenone appears to give (CF3)2NOCPh2SON(CF3)2, which decomposes above 0 deg C.
- Booth, B. L.,Browne, R. F.,Haszeldine, R. N.,Varley, J. S.
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p. 485 - 502
(2007/10/02)
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