Furan with acetone

The unsaturated tetraoxaquaterene (accompanied by linear condensation products) was first synthesized in 18.5% yield by the acid-catalyzed condensation of furan with acetone in the absence of added lithium salts. Other ketones also condensed with furan to give analogous products in 6-12% yield.A corresponding macrocycle was also prepared in 9% yield from pyrrole and cyclohexanone. The macrocyclic ether products have also been obtained by condensation of short linear condensation products having 2, 3, or 4 furan rings with a carbonyl compound. ... 

Formation of the difurylalkane skeleton has been accomplished by condensation of a 2-substituted furan derivative with a carbonyl compound under acidic conditions in other words, difurfuryl propane (18) has been produced by the condensation of furan with acetone (60). 

An analogous tetramer was reported in 1955 that resulted from the condensation of furan with acetone [8], This process is reminiscent of that reported by von Baeyer. In both cases a cyclic tetramer forms that has heteroatoms directed to the center of a macroring. 

Preparation the linear tropone-annelated benzo [c] furans 371 (X = O) by direct condensation of dialdehyde 370 (X = O) with acetone, 1-phenyl-acetone, and 1,3-diphenylacetone, in alkaline medium was—in contrast to the corresponding benzo [c]thiophene (X = S)—unsuccessful. Interestingly, this condensation has been brought about with the Diels-Alder adduct 372 subsequent heat yields 371 (X = O), a rare case where V-phenylmaleimide is used as a protective group. Compounds 371 react with V-phenylmaleimide even at room temperature to give adducts 373. 

The ion (97), acting as an electrophilic reagent, can also attack another molecule of the heterocyclic compound. Thiophene with benzaldehyde or chloral gives the dinuclear product (100 R = Ph, CC13). Pyrrole and furan react with acetone to form tetranuclear derivatives of type (101 Z = NH, O). Pyrroles with a single free position react analogously to thiophene e.g. two molecules of 3-ethoxycarbonyl-2,4-dimethylpyrrole with formaldehyde afford the dipyrromethane (102). 

The deMayo-type photochemistry of 1,3-dioxin-4-ones has been beautifully applied by Winkler et al. to the synthesis of complex natural products. Substrate 133 gave under sensitized irradiation (with acetone as cosolvent) product 134 as single diastereoisomer (Scheme 6.47). The diastereoselectivity results from cyclic stereocontrol exerted by the two stereogenic centers in the spiro-bis-lactone part of the starting material. After installation of the furan, saponification and bond scission in a retro-aldol fashion generated a keto carboxylic add, which produced the natural product ( )-saudin (135) by simultaneous formation of two acetal groups [128]. 

Typical surface preparation calls for cleaning with acetone, MEK, or other common solvent. Once clean, the substrate is then mechanically abraded with sand, grit or vapor blast, or steel wool. The surface is again wiped clean with fresh solvent. Typical adhesives that are employed include epoxies, urethanes, and cyanoacrylates. Polysulfides, furanes, and polyester adhesives have also been suggested. 

Diorgano tellurium dihalides, when refluxed with silver fluoride in toluene, tetrahydro-furan, or acetone, precipitate silver halides. The diorgano tellurium difluorides crystallize upon cooling the filtrate of the reaction mixture or evaporating the filtrate under vacuum. 

Based on these results and the disadvantageously high volatility of hexane, Huber et al. decided to develop another approach utilizing 5-hydroxymethylfurfural (5-HMF) or furfural, compounds that can be obtained from the dehydration of glucose or xylose, respectively [54-57]. The production of Cg-Ci5 alkenes from these furans is achievable by sequential aldol condensation with acetone followed by hydrogenation... 

The first naphtho[a]cyclopropene 68d was also obtained by that route. 3H-indazole was proposed as an intermediate in this reaction 78>. The reaction proceeds equally well from the triplet state of 7. However with acetone light capture from the sensitizer may not have been complete. A trapping of the diradical intermediate 67 to give the known indene 69 by photolysing 7 in dimethyl-acetylene-dicarboxylate (ADC) afforded only a trace of 69. However the yield of 68a was reduced to 40%. Either trapping of 67 was not effective enough or ADC may have acted as quencher. Trapping with furan or cyclopentadiene was also not effective 78a). 

In certain cases, a photochemical 2,5-oxidation can also be carried out. Wasserman and Liberies275 oxidized tetraphenylfuran in methanolic solution, by irradiation and treatment with atmospheric oxygen, and obtained 2,5-dimethoxy-2,3,4,5-tetraphenyl-2,5-dihydro-furan. In acetone the furan ring is cleaved ... 

TpRe(CO)(PMe3) produces a variety of stable rj complexes of the type TpRe(CO)(PMe3)() -E) (E = cyclohexene, cyclopentene, naphthalene, phenanthrene, thiophene, 2-methylthiophene, furan, or acetone). They are obtained by reduction of the Re complex TpRe(CO)(PMe3)(OTf) with Na/Hg in the presence of the unsaturated ligand. 

Enantiomerically pure 3-oxo-8-oxabicyclo[3.2.1]octyl-2-yl derivatives were obtained by [4 -h 3] cycloaddition of furan with chiral 1,2-dioxyallyl cation engendered in situ by acid-catalyzed heterolysis of enantiomerically pure, mixed acetals derived from 1,1-dimethoxy-acetone and enantiomerically pure, secondary benzyl alcohols [203]. For instance, mixed acetal 439 is converted into the silyl enol ether 440. In the presence of a catalytic amount of trimethylsilyl triflate, 440 generates a cationic intermediate that adds to furan at - 95°C, giving... 

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