- Trithioorthoester Exchange and Metathesis: New Tools for Dynamic Covalent Chemistry
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To expand the toolbox of dynamic covalent and systems chemistry, we investigated the acid-catalyzed exchange reaction of trithioorthoesters with thiols. We found that trithioorthoester exchange occurs readily in various solvents in the presence of stoichiometric amounts of strong Bronsted acids or catalytic amounts of certain Lewis acids. The scope of the exchange reaction was explored with various substrates, and conditions were identified that permit clean metathesis reactions between two different trithioorthoesters. One distinct advantage of S, S, S-orthoester exchange over O, O, O-orthoester exchange is that the exchange reaction can kinetically outcompete hydrolysis, thereby making the process less sensitive to residual moisture. We expect that the relatively high stability of the products might be beneficial in future supramolecular receptors or porous materials.
- Bothe, Michael,Furlan, Ricardo L. E.,Orrillo, A. Gastón,Von Delius, Max
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supporting information
p. 1988 - 1994
(2019/10/22)
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- Catalytic thione-thiol rearrangement of xanthates by 4- dialkylaminopyridine
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Pyridines bearing electron-donating substituents are useful catalysts for the rearrangement of O,S-dialkyl xanthates (1) to S,S-dialkyl dithiocarbonates (2). The rearrangement was analyzed by semiempirical and ab initio molecular orbital methods. The transition-structure analyses indicate that the pyridine-ring nitrogen of dialkylaminopyridine rather than the dialkylamino nitrogen attacks the O-alkyl carbon of xanthates. The reaction proceeds through an S(N)2 mechanism to give the dithiolcarbonate anion (RSCOS-) which acts as an actual catalyst.
- Nakagawa, Hidetoshi,Eto, Masashi,Harano, Kazunobu
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- Thiyl radicals in gas-phase thermolysis of xanthic acid esters
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Gas-phase thermolysis of xanthic acid esters and their reaction with acetylene at 250-600°C have been studied for the first time. The direction of the thermolysis is determined by the nature of the substituents at the oxygen and sulfur atoms. The main products of the thermolysis are gaseous hydrocarbons, carbon monoxide and hydrogen sulfide. The yields of liquid products of the thermolysis and of the reactions with acetylene are 4-46 %. The role of thiyl radicals in thiophene molecule formation and reaction routes to carbon disulfide, dithiocarbonates, and stilbene are discussed.
- Deryagina,Korchevin,Russavskaya,Sukhomazova,Levanova
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p. 140 - 143
(2007/10/03)
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- Thione-thiol rearrangement of xanthates catalyzed by pyridine N-oxides. Remarkably enhanced reactivity of 4-dialkylaminopyridine N-oxides
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Pyridine N-oxides bearing electron-donating substituents (III) are efficient catalysts for rearrangement of O-alkyl S-methyl dithiocarbonates (xanthates) (I) to the corresponding S-alkyl S-methyl dithiocarbonates (dithiolcarbonates) (II). Of the catalysts tested, 4-piperidinopyridine N-oxide (IIIh) is the best from the viewpoints of catalytic activity and solubility in I. Heating of I in the presence of catalytic amounts (0.02-0.05 molar eq) of IIIh gave II together with the symmetric S,S-dialkyl and S,S-dimethyl dithiocarbonates in good yields. The catalytic behavior of donor-substituted pyridine N-oxides is discussed on the basis of kinetic and molecular orbital calculation data. The complete calculation of the perturbation equation on the initial stage of the reaction was consistent with the experimentally observed activity of the catalysts.
- Harano,Nakagawa,Kamei,Kiyonaga,Hisano
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p. 1675 - 1682
(2007/10/02)
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- Catalytic Rearrangement of O,S-Dialkyl Dithiocarbonates to S,S-Dialkyl Dithiocarbonates by Pyridine N-Oxides. The Reaction Mechanism
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The reaction of O-alkyl S-methyl dithiocarbonates (xanthates) (I) with pyridine N-oxides (II) gave the corresponding S-alkyl S-methyl dithiocarbonates (dithiolcarbonate) (III) together with the symmetric S,S-dialkyl and S,S-dimethyl dithiocarbonates in good yields.Pyridine N-oxides bearing electron-donating substituents are efficient catalysts for rearrangement of I to III.The reaction is pseudo-first-order and the apparent first-order rate constant is proportional to the concentration of II.The role of pyridine N-oxides and the reaction behavior of O,S-dialkyldithiocarbonates are discussed on the basis of kinetic and molecular orbital calculation data.The rearrangement may proceed by nucleophilic attack of -SCOSR derived from a complex of I and II on the O-alkyl group of xanthates.The reaction provides a useful preparation method for alkanethiols by aminolysis of the products with ethanolamine.Keywords O,S-dialkyl dithiocarbonate; S,S-dialkyl dithiocarbonate; pyridine N-oxide; thiol; charge transfer; catalytic rearrangement; kinetics; ethanolamine; frontier molecular orbital
- Harano, Kazunobu,Shinohara, Ikuo,Sugimoto, Shin-ichiro,Matsuoka, Toshikazu,Hisano, Takuzo
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p. 576 - 581
(2007/10/02)
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- 4-DIMETHYLAMINOPYRIDINE N-OXIDE AS AN EXCELLENT CATALYST FOR THIONE TO THIOL REARRANGEMENT OF XANTHATES
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4-Dimethylaminopyridine N-oxide effectively catalyzes the thione to hiol rearrangement of O,S-dialkyl dithiocarbonates (xanthates) to provide S,S-dialkyl dithiocarbonates.
- Harano, Kazunobu,Kiyonaga, Hideo,Sugimoto, Shin-ichiro,Matsuoka, Toshikazu,Hisano, Takuzo
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p. 2327 - 2330
(2007/10/02)
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