97511-21-2Relevant academic research and scientific papers
CATALYZED LIQUID-PHASE OXIDATION OF DIALKYLTHIOPHENES
Volkov, M. N.,Kazakova, O. A.
, p. 553 - 557 (1981)
The oxidation of 3-methyl-2-ethylthiophene with molecular oxygen in glacial acetic acid in the presence of cobalt-bromide catalyst was investigated.It was established that there is a dependence of the rate of oxidation of this compound on its concentration, on the catalyst (cobalt acetate) concentration, and on the initiator (NaBr) concentration.The principal oxidation products are 3-methyl-2-acetothienone (III) and 1-(3-methyl-2-thienyl)ethyl acetate, which were isolated and characterized.The reactivity of 3-methyl-2-ethylthiophene in the oxidation reaction is higher than that of 4-methyl-2-ethylthiophene.
Practical access to metallo thiophenes: Regioselective synthesis of 2,4-disubstituted thiophenes
Asselin, Sylvie M.,Bio, Matthew M.,Langille, Neil F.,Ngai, Ka Yi
supporting information; experimental part, p. 1427 - 1431 (2011/09/20)
This report describes a protocol for functionalization of thiophenes, utilizing a regioselective magnesiation mediated by commercial Grignard reagents and catalytic 2,2,6,6-tetramethylpiperidine. This metalation provides practical access to metallo thiophenes, avoiding cryogenic conditions, prolonged reaction times, and prohibitively expensive reagents. Application to a target thiophene-phthalazinone 6 was accomplished by addition of 2-magnesio-4- methylthiophene to phthalic anhydride, providing the product with >40:1 regioselectivity. This also solved a chemoselectivity issue encountered with analogous lithio-thiophene reagents and cyclic anhydrides, or with magnesio-thiophene generated by simultaneous lithium-to-magnesium transmetalation/anhydride acylation. These alternative in situ transmetalation sequences were plagued by an age effect dictated by the kinetic solubility of MgCl2/THF complexes.
A highly active ytterbium(III) methide complex for truly catalytic Friedel-Crafts acylation reactions
Barrett, Anthony G. M.,Bouloc, Nathalie,Braddock, D. Christopher,Chadwick, David,Henderson, David A.
, p. 1653 - 1656 (2007/10/03)
The Friedel-Crafts acylation of anisole with acetic anhydride using ytterbium(III) tri[tris(nonafluorobutanesulfonyl)methide] was studied with respect to catalyst loading. A strong inhibitory effect due to the product became apparent from doping experiments and from examination of the kinetic data. This understanding allowed catalyst loadings to be reduced to as little as 0.1 mol% for effective acylation under a suitable temperature and pressure regime.
Photoisomerization of 2H,6H-Thiin-3-one 1-Oxides to 3H,7H-Oxathiepin-4-ones
Kowalewski, Ronald,Margaretha, Paul
, p. 1251 - 1257 (2007/10/02)
Oxidation of 2H,6H-thiin-3-ones 1a-c with 3-chloroperbenzoic acid affords the corresponding 1-oxides 2a-c.On irradiation (350 nm) in either benzene or MeCN, these cyclic sulfoxides 2 isomerize to 3H,7H-1,2-oxathiepin-4-ones 3.The tetramethyl derivative 3a is isolated by flash chromatography at -10 deg C, but at higher temperatures, it undergoes ring contraction and H2O elimination to give 4,4-dimethyl-2-(2-methylprop-2-enylidene)thietan-3-one (4).Dimethyloxathiepinones 3b and 3c undergo ring contraction in MeOH to afford 1-(4-methylthiophen-2-yl)ethanone (5) and two diastereoisomeric 4,4-dimethyl-2-methoxy-2-(1-methoxyethyl)thietan-3-ones (6 and 7, respectively).
Kinetics of the Detritiation of a Series of 4- and 5-Substituted 2-(acetyl)thiophenes
Jones, John R.,Pearson, Gerd M.,Spinelli, Domenico,Consiglio, Giovanni,Arnone, Caterina
, p. 557 - 558 (2007/10/02)
A series of 4- and 5-substituted 2-(acetyl)thiophenes have been prepared and the kinetics of the hydroxide-catalysed detritiation studied at 25.0 deg C.The second-order detritiation rate constants parallel those observed for the corresponding meta- and para-substituted acetophenones but as the reaction constant ρ is higher (1.61) the range of reactivity is much wider than that witnessed for the acetophenones.
