- The conundrum of odourless Kahweofuran, a roasting “flavour” of coffee
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A new synthesis of the dihydrothieno [2,3-c]furan Kahweofuran, isolated from coffee extracts, reveals it probably does not possess the intense and ‘violent’ sulfurous odour previously ascribed to it. We speculate that trace amounts of thiol compound(s) present as impurities in the original isolate and perhaps in other synthetic samples are instead responsible. Key steps in the present approach are a 5-endo-dig iodocyclisation to establish the furan ring and a final, highly efficient copper-catalysed intramolecular C–S bond formation of the intermediate 3-iodofuran.
- King, Ian S.C.,Knight, David W.
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- Novel synthesis of kahweofuran: A flavour component of roasted coffee
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Kahweofuran (1), one of the impact flavours of roasted coffee and possesses 6-methyl-2, 3-dihydrothieno[2,3-c]furan structure, was obtained from 4,5-dihydrothiophen-3(2H)-one through six steps.
- Li, Weili
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- Production of kahweofuran or its derivatives (by machine translation)
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Efficient synthesis of [be] kahweofuran or derivatives thereof. 3 - Hydroxy methylthiophene 2 position of the hydroxyalkyl group is introduced into the [a], 3 position hydroxyl protecting group to introduce substituents, hydroxy substituents at the 2 oxidation process, hydroxyl group deprotection step 3 substituted, in the presence of a transition metal catalyst obtained in the intermediate ring (6) and a step of reducing a compound comprising a manufacturing method. [Drawing] no (by machine translation)
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- NOVEL THIOPHENE COMPOUND AND PROCESS FOR PRODUCING CAFFENOFURAN OR ANALOGUE THEREOF FROM THE SAME
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The present invention provides a novel thiophene compound as a synthetic intermediate that is useful for efficient production of kahweofuran or an analogue thereof. The present invention also provides a process for producing kahweofuran or an analogue thereof using the novel thiophene compound as an intermediate material. Of novel thiophene compounds represented by Formula (1): wherein R1 is a hydrogen atom or a C1-C4 lower alkyl group; R2 is a hydrogen atom or an alcohol-protecting group; R3 is a hydrogen atom, -COR4 or -C(OH)R5 (wherein R4 and R5 each represent a C1-C4, lower alkyl group); provided that when R2 and R3 are hydrogen atoms, R1 is not any of a hydrogen atom, methyl group, or n-propyl group; a thiophene compound represented by Formula (2) is reduced and cyclized in the presence of a transition metal catalyst to produce kahweofuran or kahweofuran analogue (3a) shown below: wherein R1 is a hydrogen atom or a C1-C4 lower alkyl group, and R4 is a C1-C4 lower alkyl group.
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- Rapid synthesis of kahweofuran and its derivatives, the coffee aroma components
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Kahweofuran, as an impact flavor component of roasted coffee and possesses the 6-methyl-2,3-dihydrothieno[2,3-c]furan structure, was rapidly synthesized from 2-acetyl-3-hydroxymethylthiophene by the formal reductive cyclization using the Wilkinson's catalyst. Similarly, the syntheses of the 4-methyl, 6-ethyl and 4,6-dimethyl derivatives were also achieved in favorable yields.
- Li, Yanwu,Murakami, Yusuke,Katsumura, Shigeo
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p. 787 - 789
(2007/10/03)
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- Synthesis of 2,3-Dihydro-6-methylthienofuran (Kahweofuran), a Coffee Aroma Component, from an Acyclic Precursor
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Kahweofuran 1, one of the impact flavours of roasted coffee, was obtained from the acyclic unsaturated ester 8, produced in a Stobbe condensation of α-methylcinnamaldehyde 6 with dimethyl succinate 7, through the key intermediate tetrahydrothiophene 14 and the C-7 derivatives 20 or 24, respeectively.
- Brenna, Elizabetta,Fuganti, Claudio,Serra, Stefano,Dulio, Andrea
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p. 551 - 563
(2007/10/03)
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- Synthesis of Alkyl-2,3-dihydrothienofurans, Aroma Compounds of Coffee
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Starting with 3,4-dihalofurans 1 and using furyllithium compounds as intermediates the 3-halo-4-(2-haloethyl)furans 3, 8-10, and 14 are synthesized.They are transformed into the corresponding 3-lithio-4-(2-haloethyl)furans which react with sulfur at -80 deg C to form lithium-3-thiolates and cyclize spontaneously at higher temperature to afford the 2,3-dihydrothienofurans 4, 11, and 15.By this reaction sequence 2,3-dihydro-6-methylthienofuran (kahweofuran) (4c), a roasting aroma component of coffee, is synthesized in 12percent overall yield.Eight mono-, di-, and trialkyl-substituted 2,3-dihydrothienofurans, its sulfoxide 5 as well as 4-formyl derivative 16 and the 4-methoxycarbonyl derivative 17 of kahweofuran are described.
- Gorzynsky, Marek,Rewicki, Dieter
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p. 625 - 637
(2007/10/02)
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