Tetra hydrofuran

The conversion of primary alcohols and aldehydes into carboxylic acids is generally possible with all strong oxidants. Silver(II) oxide in THF/water is particularly useful as a neutral oxidant (E.J. Corey, 1968 A). The direct conversion of primary alcohols into carboxylic esters is achieved with MnOj in the presence of hydrogen cyanide and alcohols (E.J. Corey, 1968 A,D). The remarkably smooth oxidation of ethers to esters by ruthenium tetroxide has been employed quite often (D.G. Lee, 1973). Dibutyl ether affords butyl butanoate, and tetra-hydrofuran yields butyrolactone almost quantitatively. More complex educts also give acceptable yields (M.E. Wolff, 1963). 

The submitters used sodium amide (obtained from Fluka A G as small lumps under kerosene) which was washed with anhydrous tetra-hydrofuran and ground with a mill. The checkers used freshly opened and recently purchased cans of sodium amide powder (Fisher Scientific Company) older reagent gave unsatisfactory results. 

The yield is determined by weighing the cold trap before and after distillation of methylenecyclopropane. Any small amounts of tetra-hydrofuran carried into the methylenecyclopropane trap are eliminated in a subsequent distillation. By proton magnetic resonance analysis the checkers found that no tetrahydrofuran reached the cold traps the spectrum (dichloromethane) shows a triplet at S 1.00 and a quintuplet at S 5.35 in the ratio 4 2. 

In a 250 ml Erlenmeyer flask covered with aluminum foil, 14.3 g (0.0381 mole) of 17a-acetoxy-3j5-hydroxypregn-5-en-20-one is mixed with 50 ml of tetra-hydrofuran, 7 ml ca. 0.076 mole) of dihydropyran, and 0.15 g of p-toluene-sulfonic acid monohydrate. The mixture is warmed to 40 + 5° where upon the steroid dissolves rapidly. The mixture is kept for 45 min and 1 ml of tetra-methylguanidine is added to neutralize the catalyst. Water (100 ml) is added and the organic solvent is removed using a rotary vacuum evaporator. The solid is taken up in ether, the solution is washed with water and saturated salt solution, dried over sodium sulfate, and then treated with Darco and filtered. Removal of the solvent followed by drying at 0.2 mm for 1 hr affords 18.4 g (theory is 17.5 g) of solid having an odor of dihydropyran. The infrared spectrum contains no hydroxyl bands and the crude material is not further purified. This compound has not been described in the literature. 

Ethoxyacetylene A solution of 7 g of estrone methyl ether in tetra-hydrofuran (80 ml) is slowly added with stirring to ethoxyethynylmagnesium bromide (from ethoxyacetylene, 9 g, and 3 M ethereal methyhnagnesium bromide, 32 ml) and the mixture is refluxed overnight with stirring. Aqueous... 

Although potassium fluoride is the preferred nucleophile, tetiabutylam-monium fluoride (TBAF) is successfully used for aromatic fluorodenitration o Fluoronitrobenzene can be obtained in quantitative yield from o-dinitrobenzene in tetra hydrofuran at 25 °C after 1 5 h 7]... 

Early attempts to metalate 1,1-difluoroethylene with -butyllithium in tetra-hydrofuran or diethyl ether were unsuccessful. Another example whereby the course of the reaction may be altered by substitution of rec-butyllithium in place of n-butyllithium is the metalation of 1,1 -difluoroethylene [60] (equation 26)... 

Synthesis of Annonaceae acetogenins with long aliphatic chain including tetra-hydrofuran fragments 97YGK877. 

A 0.60 g portion of N-carbobenzoxy-D-phenylglycine is dissolved in 10 ml of dry tetra-hydrofuran. The solution is cooled in an ice-salt bath, and to it is added 0.29 ml of tri-ethylamine with stirring over a period of 10 minutes, followed by 0.29 ml of isobutyl chloroformate, after which stirring is continued for 10 minutes at -5°C. During this time,... 

As an indication of the changes in deformation modes that can be produced in ionomers by increase of ion content, consider poly(styrene-co-sodium methacrylate). In ionomers of low ion content, the only observed deformation mode in strained thin films cast from tetra hydrofuran (THF), a nonpolar solvent, is localized crazing. But for ion contents near to or above the critical value of about 6 mol%, both crazing and shear deformation bands have been observed. This is demonstrated in the transmission electron microscope (TEM) scan of Fig. 3 for an ionomer of 8.2 mol% ion content. Somewhat similar deformation patterns have also been observed in a Na-SPS ionomer having an ion content of 7.5 mol%. Clearly, in both of these ionomers, the presence of a... 

The polymerisatibh of c-cstproliactarn is sbmetiiries known as a ring-, opening polymefisation, a, technique also. hsed with ethylene ioxide, tetra- hydrofuran and a numl r of other rhanoirters. 

When 2,7-dimethyloxepin is treated with potassium in liquid ammonia at — 70 C, a mixture of oct-4-en-2-one (1) and octa-4,6-dien-2-one (2) in a ratio of 75 20 is obtained.203 The major product can be separated by preparative gas chromatography in 23% yield. The analogous reaction of 3-benzoxepin gives, in 30% yield, a mixture of (2-cthylphenyl)acetaldehyde (3) and (2-ethynylphenyl)acetaldehyde (4) that resists separation.203 The Latter product can be formed exclusively in 17% yield when 3-benzoxepin is treated with sodium amide in tetra-hydrofuran at 33 C for 210 minutes.203... 

Mori et al. have demonstrated the most dramatic uses of lithiated epoxides in natural product synthesis [62]. By employing the chemistry developed by Jackson, and subsequently performing a Lewis acid-catalyzed (BF3 OEt2) cyclisation, tetra-hydrofuran, tetrahydropyran, and oxepane rings are readily accessed this strategy is demonstrated by the synthesis of the marine epoxy lipid 173 (Scheme 5.40) [63]. 

Keumi et al. (1989) describe hydro-de-diazoniations of arenediazonium tetrafluo-roborates using chlorotrimethylsilane, (CH3)3SiCl), in tetrahydrofuran or tetra-hydrofuran/A A-dimethylformamide mixtures. Excellent yields were obtained with polycyclic arene derivatives such as 2-fluorene-, 2-fluorenone-, and 1-pyrenediazo-nium tetrafluoroborate and other similar diazonium salts. In a modification of this method 2-halogenofluorenones can be synthesized (see Sec. 10.6). 

A similar substitution pattern can be obtained by applying a thermal protocol as well [75]. Ortho-methoxyphenol 131 has been synthesised in good yields by warming the cyclobutene-containing 1,3,5-metallatriene 130 in tetra-hydrofuran (Scheme 55). 

Unreacted chloride remains at the end of the roaetion (with R2CuLi 15%, with RLi 40%) 1.5 equivalents of R2CuLi per equivalent of chloride givos 95% (. /)-2-undecene after 5 days at 25°. e A volumo of THF equal to that of the ether present was added after formation of the cuprate was complete. THF tetra-hydrofuran HMPA hexamethylphosphoric triamide EtaO diethyl ether DME 1,2-diinethoxyethane. 

Bromhydrine konnen mit Lithiumalanat/Titan(III)-chlorid (1 4) in siedendem Tetra-hydrofuran in guten Ausbeuten in die entsprechenden Olefine ubergefiihrt werden8 9 ... 

Hall and Steuck polymerized 2 with a variety of Lewis and Bronsted acids or oxonium salts. The best conditions for the polymerization proved to be the use of phosphorus pentafluoride in methylene chloride solution at -78 °C. Yields of methanol-insoluble polymers ranging from 68 to 84% were obtained with inherent viscosities of 0.26—0.33 dl/g. Lower or higher temperatures gave lower yields. Tetra-hydrofuran as solvent at —78 °C gave 68-92% yields of materials having inherent viscosities of 0.12-0.14 dl/g. No incorporation of tetrahydrofuran into the polymer occurred. 

Net F-polarization (A at 56-4 MHz) has been observed during the reaction of p-fluorobenzyl chloride with sodium naphthalene in tetra-hydrofuran solution to give p, p -difluorobibenzyl (Rakshys, 1971). The spin selection is believed to take place within a radical pair of the -------------------------------F... 

With radical ions, the dimerization equilibrium is strongly influenced by the solvation and association of radical ions with counter ions. It has been shown that the free ions dimerize much more slowly than do the respective contact ion pairs e.g., the quinoline radical anion does not dimerize in the powerfully solvating hexamethylphosphoramide, but it does dimerize rapidly in tetra-hydrofuran (160). Thus, two equilibria should be distinguished (160), viz. 

Thiemer B, JR Andreesen, T Schrader (2003) Cloning and characterization of a gene cluster involved in tetra-hydrofuran degradation in Pseudonocardia sp. strain Kl.Arch Microbiol 179 266-277. 

The reaction of carboxylic acids with CDI is surprisingly insensitive to steric hindrance. For example, from 2,4,6-tri-terf-butylbenzoic acid and CDI in refluxing tetra-hydrofuran the sterically very crowded AT-(2,4,6-tri-ter butylbenzoyl)-imidazole was obtained in 80% yield.[13]... 

Calf Thymus 5 mM Sodium Cacodylate (7.1) 0.2% Tetra-hydrofuran 25 12,000... 

Scheme 1. Chemistry at the bridged carbon centers for Compound 3. Key R, CeH Me-4 i, MeC2Me in PhMe ii, HBFh EtsO iii, k[BH(CHMeEt)s] in tetra-hydrofuran (THF) and iv, PMe2Ph. (Reprinted with permission from Ref. 12. Copyright 1981, Royal Society of Chemistry.)...

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