- A green and sustainable method for the oxidation of 1,3-dihydrobenzo[c] thiophenes to sulfones using metalloporphyrin complexes
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Two efficient methods are reported for the oxidation of 1,3-dihydrobenzo[c]thiophenes to sulfones in good to high yields using H 2O2 in the presence of catalytic amounts of porphyrin-based catalysts in ethanol or acetonitrile as solvents at room temperature. The presence of electron-donating or electron-withdrawing groups, in the benzene ring of 1,3-dihydrobenzo[c]thiophene, is well tolerated.
- Da Silva, Gustavo,Pires, Sónia M.G.,Silva, Vera L.M.,Sim?es, Mário M.Q.,Neves, M. Gra?a P.M.S.,Rebelo, Susana L.H.,Silva, Artur M.S.,Cavaleiro, José A.S.
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Read Online
- Quest for diatomic selenium
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Metallocene pentaselenides and elemental selenium were employed in an effort to generate diatomic selenium (Se2) under thermal conditions. Trapping experiments were carried out with six dienes. A successful formation of a diselenium adduct was observed in the case of 5,6-dimethylene-cyclohexa-1,3- diene (1a). The other dienes produced the corresponding dihydroselenophenes. The in-depth study of the limitations of our method to generate Se2 is described; a plausible mechanism rationalizing the observed results is proposed.
- Rys, Andrzej Z.,Schultz, Erwin K. V.,Harpp, David N.
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scheme or table
p. 351 - 371
(2011/01/12)
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- Organic Reactions of Reduced Species of Sulfur Dioxide
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Rongalite (sodium hydroxymethanesulfinate or sodium formaldehydesulfoxylate) reacts with organic halides in a variety of ways depending on the structure of the organic compound.Benzyl and other alkyl halides give sulfones in generally good yields; but in several cases, reduction (2,4-dinitrobenzyl bromide, phenacyl halides) or coupling (p-nitrobenzyl bromide under basic conditions, phenacyl bromide or iodide) of the halide occurs.Addition of sodium iodide to the mixture of Rongalite and phenacyl chloride changed the reaction from one of complete reduction to acetophenone to one of mainly dimerization to 1,4-diphenyl-1,4-butanedione.The amount of acetophenone from phenacyl bromide depends on the water content of the reaction mixture, more dimer being formed when little water is present.Diphenacyl sulfone is formed from phenacyl bromide and Rongalite in the presence of excess sulfur dioxide.The intermediate β-keto sulfinate is believed to normally lose sulfur dioxide very readily to give the enolate anion, which either is protonated to give acetophenone or reacts with phenacyl halide to give the butanedione.In the presence of excess sulfur dioxide, the loss of sulfur dioxide from the sulfinate is supressed, allowing sulfone formation to occur by reaction of the sulfinate with phenacyl halide. o-Xylylene dibromide gave o-xylylene, trapped as the Diels-Alder adduct with norbornene, along with the expected cyclic sulfone and cyclic sulfinate ester (sultine).A convenient synthesis of the sultine in 78percent yield is achieved by treatment of α,α'-dichloro-o-xylene with Rongalite and sodium iodide.Treatment of Rongalite in DMF-H2O with sulfur dioxide gives the blue anion radical complex (SO2)(SO2.-).Anion radicals are produced from p-dinitrobenzene and p-nitrobenzoate ion when they are treated with Rongalite.
- Jarvis, William F.,Hoey, Michael D.,Finocchio, Alfred L.,Dittmer, Donald C.
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p. 5750 - 5756
(2007/10/02)
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- o-Quinodimethanes from 3,6-Dihydrobenzo-1,2-oxanthiin-2-oxides
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A two step synthesis of 3,6-dihydrobenzo-1,2-oxanthiin-2-oxide 5a from o-tolualdehyde via the photochemically produced 1-hydroxy-1,3-dihydrobenzothiophene-2,2-dioxide is described.Analoguos syntheses of 3 and 6 substituted derivatives of the benzosu
- Charlton, James L.,Durst, Tony
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p. 5287 - 5290
(2007/10/02)
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