- Synthesis, Structure, and Properties of Quinone Methides Incorporating Thiophene and Bithiophene Derivatives: New Overcrowded Extended Quinonoid π-Systems
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The title compounds were synthesized through multiple Suzuki-Miyaura couplings followed by oxidation, and their structures and properties are described. They show large conformational changes and three color change upon electronic reduction.
- Kurata, Hiroyuki,Inoue, Taihei,Suzuki, Takeshi,Hirao, Yasukazu,Matsumoto, Kouzou,Kubo, Takashi
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- Synthesis of Thieno--, -- and --thiophenes and Thieno--, -- and --thienopyrimidin-7(6H)-ones Starting from Thiophene
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3-Bromo-, 3,5-dibromo- and 3,4,5-tribromo-2-thienyllithium have been prepared by bromine ->lithium exchange and converted into a number of thiophene derivatives, including the corresponding 2-carbaldehydes.The aldehydes have been converted into the corresponding thiophene-2-carbonitriles.Metallation of 2,5-dibromo- or 2,4,5-tribromo-thiophene with LDA occured at a vacant 3-position but the resulting 3-lithiated thiophenes rearranged (mechanism discussed) to 3,5-dibromo- and 3,4,5-tribromo-2-thienyllithium, which were quenched with various electrophiles.Attempts to dilithiate 2,5-dibromothiophene with LDA were unsuccessful. 3,4-Dibromo-2,5-dilithiothiophene was prepared from 2,3,4,5-tetrabromothiophene but it failed to yield the 2,5-dicarbaldehyde with N,N-dimethylformamide.The title thienothiophenes were prepared by reaction of a 3-bromothiophene-2-carbaldehyde, a 2-bromothiophene-3-carbaldehyde (prepared by bromination of a thiophene-3-carbaldehyde) or a 4-bromothiophene-3-carbaldehyde, or a corresponding nitrile, with ethyl 2-sulfanylacetate or 2-sulfanylacetamide.Thienothiophenes carrying an o-aminocarboxamide substitution pattern gave the title thienothienopyrimidinones with triethyl orthoformate.
- Hawkins, David W.,Iddon, Brian,Longthorne, Darren S.,Rosyk, Peter J.
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p. 2735 - 2744
(2007/10/02)
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- 3,4-Dibromothiophene from 2-Bromothiophene
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3,4-Dibromothiophene can be obtained in a reasonable yield by treating the readily available 2-bromothiophene with a mixture of equimolar amounts of sodamide and potassium tert-butoxide in liquid ammonia.
- Brandsma, L.,Verkruijsse, H.D.
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p. 2119 - 2122
(2007/10/02)
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- The electroreduction of halogenated thiophenes
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Electroreduction of polyhalothiophenes results in the preferential reduction of the α-halogen atoms.Preparative electrochemical reduction of these compounds at controlled potential can be used to synthesize 2,3,4-trihalo, 3,4-dihalo, and 3-halothiophenes.Experimental conditions were developed under which these reductions could be done selectively, giving good yields of the desired products.Electroreduction of tetrabromothiophene can also lead to the formation of a polybromodithyenyl mercury compound.
- Gedye, Richard Neville,Sadana, Yoginder Nath,Leger, Raymond
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p. 2669 - 2672
(2007/10/02)
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- Polyhalogenoaromatic Compounds. Part 41. Photochemical Dehalogenation and Arylation Reactions of Polyhalogenoaromatic and Polyhalogenoheteroaromatic Compounds
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Photolysis of pentachloro- and pentabromo-pyridine in diethyl ether or methanol leads to loss of β-halogen.A product (9) derived from attack on diethyl ether was also identified. 4-Bromotetrachloropyridine also undergoes loss of bromine and tetrachloro-4-iodopyridine loses iodine exclusively.Photodehalogenation of some perhalogenothiophens, tetrachloropyrimidine, and hexachlorobenzene is also described.Photolysis of pentachloroiodobenzene, tetrachloroiodopyridines, and trichloro-5-iodothiophen in benzene gives the corresponding polychloroaryl- or polychloroheteroaryl-benzenes.Photolysis of tetrachloro-4-(phenylthio)pyridine (3) gives 1,3,4-trichlorobenzothienopyridine (6), and the analogous perchloro(phenylthio)pyridine (37) gives the corresponding perchlorobenzothienopyridine (61).The scope of this type of photocyclisation has been explored; starting materials investigated include various arylthiopolyhalogenopyridines, some arylamino- and aryloxy-tetrachloropyridines, and 4-anilinotrichloropyrimidine.
- Bratt, Jack,Iddon, Brian,Mack, Arthur G.,Suschitzky, Hans,Taylor, Jack A.,Wakefield, Basil J.
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p. 648 - 656
(2007/10/02)
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