A Short and Economical Synthesis of 2,2,7,7-Tetramethyl-4-Octene -3,6-dione from 2-Furoic Acid and t-Butyl Chloride

Fitzpatrick, John E.; Milner, David J.; White, P.C.

doi:10.1080/00397918208065957

Cited by 26 publications

(13 citation statements)

References 6 publications

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“…The starting (2-aminophenyl)bis(2-furyl)methanes were prepared from commercially available 2-nitrobenzaldehydes 1a-d and easily synthesized 2-tert-butylfuran (2) 9 by the reaction sequence shown in Scheme 1. The perchloric acid catalyzed condensation of 2-nitrobenzaldehydes 1a-d with 2-tert-butylfuran (2) in 1,4-dioxane afforded (2-nitrophenyl)bis(2-furyl)methanes 3a-d.…”

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confidence: 99%

Recyclization of (2-Aminophenyl)bis(5-tert-butyl-2-furyl)methanes into Indole Derivatives: Unusual Dependence on Substituent at Nitrogen Atom

Бутин¹,

Smirnov²,

Tsiunchik³

et al. 2008

Synthesis

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R e c y c l i z a t i o n o f ( 2 -A m i n o a r y l ) b i s ( 5 -t e r t -b u t y l -2 -f u r y l ) m e t h a n e s Abstract: The recyclization of (2-aminophenyl)bis(5-tert-butyl-2-furyl)methanes under acidic conditions was studied. It was found that the extent of reaction of these substrates depends on the substituent at the nitrogen atom of the aniline moiety. N-Tosyl derivatives were converted into the corresponding 3-(5-tert-butyl-2-furyl)-2-(4,4-dimethyl-3-oxopentyl)-1-tosyl-1H-indoles. Indole formation was followed by furan ring opening in the case of N-unsubstituted substrates leading to 3-(5,5-dimethyl-1,4-dioxohexyl)-2-(4,4-dimethyl-3-oxopentyl)-1H-indoles. The same products were obtained from N-acetyl derivatives. However, the behavior of the N-benzoyl analogues depends on the reaction conditions: at room temperature 1-benzoyl-3-(5-tert-butyl-2-furyl)-1H-indoles were formed, but debenzoylation and furan ring opening proceed with heating. These data and results of control experiments showed that the reaction mechanism consists of three successive steps: recyclization itself, deacylation of the resulting N-acylindole, and furan ring opening in N-unsubstituted 3-(2-furyl)indoles. The last step can be realized for N-unsubstituted indoles only, but the furan ring is stable for Nacylindoles. This was explained by transformation of N-unsubstituted 1H-indoles under the reaction conditions into 3H-indole tautomers. These tautomers can be considered as 2,5-dialkylfurans, which have much lower stability against acids than 2-aryl-5-alkylfurans. This tautomerization is impossible for N-acylindoles. The high acidic stability of 2-(5-tert-butyl-2-furyl)indoles supports this conclusion.

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confidence: 99%

Recyclization of (2-Aminophenyl)bis(5-tert-butyl-2-furyl)methanes into Indole Derivatives: Unusual Dependence on Substituent at Nitrogen Atom

Бутин¹,

Smirnov²,

Tsiunchik³

et al. 2008

Synthesis

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“…Synthesis of 5,5-dimethyl-1-[2-(4,4-dimethylpentan-3-on-1-yl)-1H-indol-3-yl]hexane-1,4-dione (16). A total of 35% hydrochloric acid (7 mL) was added to the cooled solution (10)(11)(12) C) of compound 12a (1.0 g, 2.2 mmol) in AcOH (25 mL). The reaction mixture was kept at 45 C for 9 h. After completion of the reaction (TLC monitoring), the mixture was poured into water, neutralized with NaHCO 3 , and extracted with CH 2 Cl 2 (3 Â 50 mL).…”

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confidence: 99%

“…The starting (2-aminoaryl)bis(2-furyl)methanes were synthesized from the commercially available ortho-nitrobenzaldehydes 8a,b and 2-(tert-butyl)furan (9) [12] according to Scheme 3. Condensation of these reagents in dioxane in the presence of catalytic quantity of perchloric acid gave rise to (2-nitroaryl)bis(5-tert-butyl-2-furyl)methanes 10a,b, which were further reduced by the treatment with hydrazine hydrate in the presence of Raney nickel [10].…”

Section: Resultsmentioning

confidence: 99%

Synthesis of tetracyclic system of 2,4‐di(tert‐butyl)‐6,7‐dihydrofuro[2′,3′:3,4]cyclohepta[1,2‐b]indole

Бутин

Kostyukova

Tsiunchik

et al. 2011

Journal of Heterocyclic Chem

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in Wiley Online Library (wileyonlinelibrary.com).For the first time, tetracyclic compounds, namely, furo[2 0 ,3 0 :3,4]cyclohepta[1,2-b]indoles were synthesized by recyclization of ortho-substituted aryldifurylmethanes containing tert-butyl groups at C5 positions of the furan rings. It was shown that [2-(benzoylamino)phenyl]bis(5-tert-butyl-2-furyl)methanes 12 are transformed into tetracycles 15 at room temperature under treatment with POCl 3 in benzene solution containing some drops of water. The reaction proceeds via the intermediate formation of 1-benzoylamino-3-(5-tert-butyl-2-furyl)-2-(4,4-dimethyl-3-oxopentyl)indoles 14 which can be isolated from the reaction mixture. The method is very simple but its application is restricted due to side reactions if electron-releasing groups are present in 12. On the other hand, the decrease of electron density on furan ring in the starting compounds (for example, the use of [2-X-phenyl]difurylmethanes (where X ¼ tosylamino or hydroxy group) prevents cyclization under the studied reaction conditions. As a result, corresponding ketones are formed as products of recyclization.

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“…The following compounds were prepared by literature methods: 2,5-diphenylfuran 1a, 1a 2,5-di-tert-butylfuran 1c, 7 3-bromo-2,4,5-triphenylfuran 6, 1a …”

Section: Experimental General Detailsmentioning

confidence: 99%

One-step synthesis of 5-acylisothiazoles from furans

Guillard

Lamazzi

Meth‐Cohn

et al. 2001

J. Chem. Soc., Perkin Trans. 1

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Premixed ethyl carbamate, thionyl chloride and pyridine (which generate thiazyl chloride, N᎐ ᎐ ᎐ SCl) in boiling benzene or toluene convert 2,5-and 2,3,5-substituted furans into 5-acylisothiazoles regiospecifically. The reactions are much faster and generally higher yielding in boiling chlorobenzene with more thionyl chloride and with pyridine or isoquinoline as base. Under the more vigorous conditions, even fully substituted 3-bromofurans give isothiazoles, with the displacement of bromine. Deactivated furans, with electron-withdrawing groups such as ester, cyano, benzoyl and phenylsulfonyl in the α-position, react under the more vigorous conditions to give 5-acylisothiazoles with the electronegative group in the 3-position. The 'activated' 2-methyl-5-phenyl-and 5-phenyl-2-phenylthio-furans react analogously, with the more electron-releasing group becoming part of the 5-acyl substituent, exclusively or predominantly. These results are explained by initial electrophilic attack of the furan ring to give a β-thiazyl derivative which spontaneously ring-opens and closes to the isothiazole. The X-ray structures of five of the differently substituted isothiazole compounds are reported. All have very similar patterns of bonding within their isothiazole rings that appear to be independent of the electron-withdrawing or -donating nature of the substituents. Three of the compounds (8a, 8g and 13) have loosely linked chain structures in the solid state, adjacent molecules being connected by combinations of hydrogen bonding and π-π stacking interactions.

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A Short and Economical Synthesis of 2,2,7,7-Tetramethyl-4-Octene -3,6-dione from 2-Furoic Acid and t-Butyl Chloride

Cited by 26 publications

References 6 publications

Recyclization of (2-Aminophenyl)bis(5-tert-butyl-2-furyl)methanes into Indole Derivatives: Unusual Dependence on Substituent at Nitrogen Atom

Recyclization of (2-Aminophenyl)bis(5-tert-butyl-2-furyl)methanes into Indole Derivatives: Unusual Dependence on Substituent at Nitrogen Atom

Synthesis of tetracyclic system of 2,4‐di(tert‐butyl)‐6,7‐dihydrofuro[2′,3′:3,4]cyclohepta[1,2‐b]indole

One-step synthesis of 5-acylisothiazoles from furans

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