Furans 3.4- diethyl

On the contrary, encapsulation of the larger K" " or NH4 ions should lead to the formation of metallacrown ether sandwich complexes (M+ MC= 1 2). Reaction of diethyl ketipinate H2L 13 with copper(ll) acetate in the presence of calcium nitrate affords green microcrystals 14 after crystallization from tetrahydro-furan/diethyl ether (Scheme 1). 

Following a series of exposures, the films were extracted successively with methanol and methylene chloride. Portions of these extracts were evaporated to dryness and the residues were taken up in 1 1 tetrahydro-furan-diethyl ether for delayed emission determinations at 77K. Emission spectra were measured in an Aminco-Bowman Spectrophosphorimeter fitted with a -P28 photomultiplier the spectra are uncorrected for instrument response. 

Benzo[b]furan-2-carboxylic acid, 6,6 -[(2-hydroxy-l,3-propanediyl)bis(oxy)]bis(3-hydroxy-diethyl ester trisodium salt trihydrate applications, 4, 709... 

Subsequently, Beals and Brown expanded the scope of the earlier work from their laboratory to include the tetraoxaquaterene derived from furan and 3-pentanone. Using 3,3-difurylpentane and diethyl ketone in the presence of dry hydrogen chloride gas, the all-ethyl analog of 6 (mp 249°) was obtained in 20% yield. ... 

In 1902 Feist first described the combination of chloroacetone (4) and diethyl 3-oxoglutarate (5) in the presence of ammonia to yield trisubstituted furan 6 ... 

Disubstituted furans are available from the combination of P-dicarbonyl compounds with bromoacetaldehyde diethyl acetal (44). For example, dibenzoylmethane (45) reacts with acetal 44 to furnish 2,3-disubstituted furan 46 in 77% yield. This two-... 

Oxidation of diethyl 3,6-hexanooxepin-4,5-dicarboxylate with ruthenium(VIII) oxide, generated from ruthenium(III) chloride and sodium periodate in situ, gives the corresponding hexa-no-bridged furan 1 a with loss of two carbon atoms (see Houben-Weyl, Vol. E6a, p 77).200 201 One of the central methylene groups can be replaced by a carbonyl group to give lb.200... 

N. A-Diethyl-2.3-dihydro-8//-thieno[2,3-r/]azcpin-7-amine (20), which is obtained in 49 % yield by photolysis of 6-azido-2,3-dihydrothiophene in a mixture of diethylamine and tetrahydro-furan. on treatment with bromine yields the fully unsaturated derivative 21.1,4... 

Similarly, triphenyltin hydride reacts with diethylzinc or diethyl-cadmium in a strongly solvating solvent, such as oxolane (tetrahydro-furan) or 1,2-dimethoxyethane, to give the solvated, metal-metal-bonded products (272). 

Analogous photoadditions have been observed on irradiation of pyrimidine and purine bases in ethers and amines. Irradiation of 1,3-dimethylur-acil (314) in tetrahydrofuran leads to the formation of 5- and 6-(tetrahydro-furan-2-yl)-5,6-dihydrouracils 315 and 316.261 Similarly, solvent adducts arising by way of initial hydrogen abstraction have been obtained on irradiation of pyrazine derivatives in diethyl ether or tetrahydrofuran.262 The... 

Pevzner, L.M., Ignatev, V.M., and Ionin, B.I., Reaction of polysubstituted (halomethyl)furans with diethyl sodiophosphite, Zh. Obshch. Khim., 64, 1108, 1994. 

Experimental Procedure 2.2.4. Benzannulation with a Ghrdinium Furylcarbene Gomplex 5,6-Diethyl-4,7-dihydrobenzo[6]furan-4,7-dione ... 

The furan products can be purified by flash chromatography and should be used at once. A mixture of ethyl acetate and methylene chloride is a good solvent system for flash chromatography. Small residues of silica tend to partly decompose these furans within two weeks. The products are hygroscopic. Diisopropyl ether-diethyl ether-hexane is a useful solvent system for recrystallization of solid furans. 

Among the various polar solvents tested, acetonitrile, dichloromethane, and THF afforded good yields of the expected product, although with moderate diastereo-selectivity (Table 16, entries 1-3). The most suitable solvent was found to be diethyl ether. 5-[Hydroxy(phenyl)methyl furan-2(5//)-one 28a was obtained with the best yield and diastereoselectivity (Table 16, entry 4). With further optimization of the reaction conditions, we found that a lower catalyst loading (0.5 mol%) did not allow the reaction to proceed (Table 16, compare entries 5 and 4), although a higher catalyst loading (5 mol%) afforded the product with close diastereoselectivity but decreased yield (Table 16, compare entries 6 and 4). 

Furan reacts with butyllithium in boiling diethyl ether to yield 2-lithiofuran, and further lithiation at C-5 occurs when this product is treated with a second equivalent of the reagent in hexane containing MMA, // -tetramethylethane-1,2-diamine (TMEDA) (Scheme 6.26a). 

Q Suggest a reaction sequence whereby furan reacts with diethyl acetylenedicarboxylate to form a compound that can be partially hydrogenated and healed to give ethene and 3.4-bis(ethoxycar-bony )furan. 

A Furan enters into a cycloaddition reaction with the dienophile diethyl acetylcnedicarboxylate to form an adduct. Catalytic reduction occurs preferentially at the more electron-rich double bond of the adduct, and the dihydro product, upon heating, undergoes a reverse Diels-Alder reaction to release ethene and the diesier (Scheme 6.29),... 

Knoevenagel condensation of the corresponding 3-methylfuran-2-carbaldehyde 379 and 3-methybenzo[4]furan-2-carbaldehyde 382 with diethyl malonate followed by bromination with iV-bromosuccinimide (NBS) in the presence of dibenzoyl peroxide afforded bromides 380 and 383, respectively. Treatment of 380 and 383 with benzylamine, isopropylamine, /-butylamine 3-hydroxypropylamine, aniline and -toluidine in ethanol yielded furo[2,3-c]pyrroles 381 and benzo[4,5]furo[2,3-c]pyrroles 384, respectively (Scheme 41). The yields of furopyrroles 381 are only moderate (16-46%), because these compounds are highly sensitive to acid, and partially polymerized upon silica... 

The series of new 4-aryl-2-phenylthieno[3,4- ]furans 396 and the selenium analogue 397 were prepared from the readily available aryl 2-bromomethyl-5-phenyl-3-furyl ketones by cyclization with thioacetamide and iV,iV-diethyl-selenopropanamide, respectively (Equation 9) <1998JHC71>. 

Amino acid-modified furocoumarins were prepared by condensation of the T-hydroxysuccinimide ester of 3-(2,3,5-trimethyl-7-oxofuro[3,2-g]chromen-6-yl)propanoic acid 51 with amino acids <2003JPH177>. Ethyl 3-(7-hydroxy-4-methyl-2-oxo-2/7-3-chromenyl)propanoate 49, prepared in 56% yield by Pechmann condensation of resorcinol and diethyl 2-acetylglutarate in the presence of HCl, was condensed with 3-chlorobutan-2-one in the presence of base to give propanoate 50 (Scheme 4). The MacLeod method was then used to fuse a furan ring to the benzopyran-2-one system. Heating 50 with NaOH solution (1 M) readily cyclized it into the corresponding psoralen furocoumarin 51 with simultaneous hydrolysis of the ester. 

In a 250-mL Schlenk tube under N2 atmosphere, a mixture of [PPN][Ir(CO)4] (0.26 g, 0.31 mmol) and Ru3(CO)i2 (0.2 g, 0.31 mmol) dissolved in tetrahydro-furan (50 mL) is refluxed for 1 h with vigorous stirring under N2 atmosphere. After removal of the solvent, the brown residue is dissolved in diethyl ether (20 mL), and the resulting solution is filtered, then concentrated 50% in volume. Addition of hexane (60 mL) to the stirred ether solution causes the precipitation of [PPN][Ru3lr(CO)i3] it is isolated in pure form by decantation as a red-brown powder, which is washed with hexane (3x10 mL) and dried in vacuo (0.36 g, 84%). 

Catalytic hydrogenation of furan Catalytic hydrogenation of furan with a palladium catalyst gives tetrahydrofuran, which is a clear, low-viscosity liquid with a diethyl-ether-like smell. 

Following sample pretreatment, extraction of the analytes from the sample matrix is usually accomplished with aqueous acetone (427), diethyl ether (435-437), acetonitrile (445), basified acetonitrile (430), or tert.-butyl methyl ether (449). Samples that have not been previously submitted to a particular treatment can also be directly partitioned with organic solvents to allow extraction of the anabolic residues from the matrix. Organic solvents most commonly used for this purpose include aqueous acetone (450), tetrahydro furan (451), methanol (447, 452, 453), tert.-butyl methyl ether (438), acetonitrile (434), and chloroform-methanol (454). 

According to the modified procedure (602), milk is thoroughly mixed in its storage container immediately before transfer of the 1 ml aliquot in the extraction tube. This is necessary because approximately 50% of phenylbutazone in milk is associated with the cream. The sample is extracted with 2.4 ml diethyl ether and 2.4 ml petroleum ether in presence of 1 ml ethanol and 100 1 25% ammonia solution. The organic layer that contains the milk lipids is discarded. Five ml hexane-tetrahydro furan (4 1) is added to the aqueous layer, which is tiien acidified with hydrochloric acid and the layers are mixed. Under the acidic conditions, phenylbutazone partitions quantitatively into tlie organic layer, which is collected, evaporated, and dissolved in the mobile phase to be analyzed by liquid chromatography. Separation is performed on a reversed-phase column using an isocratic 0.02 M phosphate buffer/methanol mobile phase, and determination is by ultraviolet detection at 264 nm (Fig. 29.18.2). The limit of detection and limit of quantification were 3.0 and 5.4 ppb, respectively (Table 29.17). 

Schonberg et al. reportedly obtained the photodimer in excellent yields when a solution of 138 in diethyl phthalate was heated to 270°C for 30 minutes and then rapidly chilled with ice water (on slow cooling no dimer was obtained see also Mustafa ). These observations could not be substantiated a product obtained in this way (mp 200°C) differed from the photodimer (comparison of IR spectra). The structure of this product is not known. A dimer was also obtained when 1,3-bis(dimethyl-aminophenyl)benzo[c]furan was treated with acetic acid with sulfuric acid it was reconverted to the monomer. . There seem to be no reports concerning the photodimerization of other benzo[cjfurans. As we have found,... 

The stoichiometric equivalents of halogen fluorides, i.e. chlorine monofluoride, bromine monofluoride and iodine monofluoride, have found a wide application in addition reactions to double bonds. The equivalents are obtained by reacting A -haloamides or free halogens in combination with hydrogen fluoride or its salts as the source of fluoride ions. The reactions proceed under mild conditions at — 80 to 20 "C in anhydrous hydrofluoric acid or diethyl ether, tetrahydro-furan, dichloromethane or chloroform mainly by electrophilic addition with Markovnikov-type regioselectivity (anti addition).26-28... 

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