- Preparation and Reaction of Methylthiofurans
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By lithiation of 3,4-dimethoxyfuran, 2-methylfuran and furan, followed by reaction with dimethyldisulfide, the methylthiofurans 2, 8, and 10 have been prepared.Reaction of 8 with maleic anhydride has yielded 6-methy1-3-(methylthio)phthalic anhydride (9), a yellow substance with a strong greenish fluorescence, obviously formed by elimination of H2O from an unstable cycloadduct.An analogous reaction of 2 resulted in an unexpected mixture from which the following yellow compounds were isolated: 3-hydroxy-4,5-dimethoxy-6-(methylthio)phthalic anhydride (3), 4hydroxy-5-methoxy-3,6-bis(methylthio)phthalic anhydride (4), and bis(S-methyl) (2Z,4E,6Z)-2,3,6,7 -tetramethoxy-4,5-bis(methylthio)-2,4,6-octatrienethioate (5).Compound 5 is also formed on standing of 2 at RT.Mild acid hydrolysis of 2 results in ring-opening accompanied by an intramolecular oxido-reduction to yield S-methyl(3Z)-3-methoxy-4-(methylthio)-2-oxo-3-butenethioate (6a).The structures of compounds 5 and 6a have been determined by X-ray analysis.
- Eugster, Conrad Hans,Balmer, Markus,Prewo, Roland,Bieri, Jost H.
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- B(C6F5)3-Catalyzed Deoxygenation of Sulfoxides and Amine N-Oxides with Hydrosilanes
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An efficient strategy for the deoxygenation of sulfoxides and amine N-oxides by using B(C6F5)3 and hydrosilanes was developed. This method provided the corresponding aromatic and aliphatic products in good to high yields and showed good functional-group tolerance under mild conditions.
- Ding, Fangwei,Jiang, Yanqiu,Gan, Shaoyan,Bao, Robert Li-Yuan,Lin, Kaifeng,Shi, Lei
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p. 3427 - 3430
(2017/07/04)
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- An analysis of substituent effects on 1H and 13C NMR parameters of substituted furans. Linear free energy relationships and PM3 semiempirical calculations
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Forty five furans have been obtained in a synthetic project designed to evaluate monothiosubstituted furans as potential food flavourings. A full NMR (1H and 13C) study and PM3 molecular orbital semiempirical calculations have been carried out. Substituent-induced chemical shifts (SCS) for six and nine substituents at the 2- and 3-positions have been calculated and a separation of inductive and resonance effects of these substituents has been proposed. Finally, a linear correlation between the net atomic charges localized at ring carbons and their 13C NMR chemical shifts has been established.
- Alvarez-Ibarra, Carlos,Quiroga-Feijoo, Maria L.,Toledano, Emilio
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p. 679 - 689
(2007/10/03)
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- Novel Heterocyclic Cage Compounds from 2-Methylthiofurans
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Some novel heterocyclic cage compounds 1a-1c were synthesized from the corresponding 2-methylthiofurans 2a-2c in a short sequence.
- Wu, Hsien-Jen,Huang, Fang-Jung,Lin, Chu-Chung
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p. 770 - 771
(2007/10/02)
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- A Tandem Oxidation-Intramolecular Diels-Alder Reaction
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Oxidation of the furan (4) with pyridinium chlorochromate gave the intramolecular Diels-Alder cycloadduct (6) as the major product, presumably via the intermediate.
- Wu, Hsien-Jen,Pan, Kai
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p. 898 - 900
(2007/10/02)
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