Ethers heterocyclic

Alcohols, ethers, and phenols including cyclic ethers, heterocyclic alcohols and ethers 00JCS(P1)2529. 

Carbon-Oxygen Linkages. Such linkages in alcohols, ethers, heterocyclic compounds, and in many other oxygenated compounds may be cleaved by hydrogen in the presence of catalysts to give a variety of products, as indicated by the following discussion. 

Cho, S.Y, Kim, S.S., Park, K.-H. etal. (1996) SynthesisofS-aUcylfluoropyridines via palladium-catalyzed cyclization of iodopyridinyl allyl ethers. Heterocycles, 43, 1641-52. 

Nomura, T., Y. Sawaura, T. Fukai, S. Yamada, and S. Tamura Studies on the Constituents of the Cultivated Mulberry Tree V. The Synthesis of Tetrahydro-kuwanon C Tetramethyl Ether. Heterocycles 9, 1355 (1978). 

Common names for ethers are derived by naming the two groups bonded to oxygen Problems 11.1,11.10,11.11 followed by the word ether. Heterocyclic ethers have an oxygen atom as one of the... 

Koyama, J., Y. Suzuta, H. Me, and I. Katayama. 1979. A new method for constructing pyridine ring Thermolysis of oxime O-aUyl ether. Heterocycles 12 157. 

Satoh, M., Mori, M., and Nakata, T. (2007) Stereoselective synthesis of the GHI-ring of maitotoxin, a marine polycyclic ether. Heterocycles, 74,259-263. 

The physical properties of a number of aliphatic ethers are collected in Table 111,60. Some related heterocyclic compounds are included in the Table. 

This reagent affords compounds (1 1) with aromatic hydrocarbons and other classes of organic compounds (heterocyclic compounds, aromatic ethers, etc.). 

Cyclic ethers have their oxygen as part of a ring—they are heterocyclic compounds... 

Cyclic ethers are named either as heterocyclic compounds or by specialist rules of heterocyclic nomenclature. Radicofunctional names are formed by citing the names of the radicals R and R followed by the word ether. Thus methoxyethane becomes ethyl methyl ether and ethoxyethane becomes diethyl ether. 

The furan nucleus is a cycHc, dienic ether with some aromaticity (2). It is the least aromatic of the common 5-membered heterocycles. A comparison of the aromaticity (3) of several of these compounds is shown below. 

In the NTC region, back-bitiag reactioas appear to be respoasible for the formation of cycHc ethers (60,165—170). la additioa to oxetanes and tetrahydrofurans, tetrahydropyrans, oxiranes, and others are also observed (60,96,169) the tetrahydrofurans are favored. 0-Heterocycle yields of 25 to 30% have been reported for / -pentane (165,171). Conjugate and other olefins are also prominent products ia this regioa (60,169—172). 

Addition compounds form with those organics that contain a donor atom, eg, ketonic oxygen, nitrogen, and sulfur. Thus, adducts form with amides, amines, and A/-heterocycles, as well as acid chlorides and ethers. Addition compounds also form with a number of inorganic compounds, eg, POCl (6,120). In many cases, the addition compounds are dimeric, eg, with ethyl acetate, in titanium tetrachloride-rich systems. By using ammonia, a series of amidodichlorides, Ti(NH2) Cl4, is formed (133). 

It melts at 39°C and may be purified by vacuum sublimation. The Hquid boils at 233°C to give a monomeric vapor in which the Ti—Br distance is 231 pm. Titanium tetrabromide is soluble in dry chloroform, carbon tetrachloride, ether, and alcohol. Like titanium tetrachloride, TiBr forms a range of adducts with molecules such as ammonia, amines, nitrogen heterocycles, esters, and ethers. 

Vinyl chloride reacts with sulfides, thiols, alcohols, and oximes in basic media. Reaction with hydrated sodium sulfide [1313-82-2] in a mixture of dimethyl sulfoxide [67-68-5] (DMSO) and potassium hydroxide [1310-58-3], KOH, yields divinyl sulfide [627-51-0] and sulfur-containing heterocycles (27). Various vinyl sulfides can be obtained by reacting vinyl chloride with thiols in the presence of base (28). Vinyl ethers are produced in similar fashion, from the reaction of vinyl chloride with alcohols in the presence of a strong base (29,30). A variety of pyrroles and indoles have also been prepared by reacting vinyl chloride with different ketoximes or oximes in a mixture of DMSO and KOH (31). 

The spectra of saturated heterocycles are generally fairly featureless, with amine n —>a absorptions and those transitions associated with sulfur showing up weakly, while saturated ethers are usually transparent down to 210 nm. 

Competitive metallation experiments with IV-methylpyrrole and thiophene and with IV-methylindole and benzo[6]thiophene indicate that the sulfur-containing heterocycles react more rapidly with H-butyllithium in ether. The comparative reactivity of thiophene and furan with butyllithium depends on the metallation conditions. In hexane, furan reacts more rapidly than thiophene but in ether, in the presence of tetramethylethylenediamine (TMEDA), the order of reactivity is reversed (77JCS(P1)887). Competitive metallation experiments have established that dibenzofuran is more easily lithiated than dibenzothiophene, which in turn is more easily lithiated than A-ethylcarbazole. These compounds lose the proton bound to carbon 4 in dibenzofuran and dibenzothiophene and the equivalent proton (bound to carbon 1) in the carbazole (64JOM(2)304). 

Large ring heterocyclic radicals are not particularly well known as a class. Their behavior often resembles that of their alicyclic counterparts, except for transannular reactions, such as the intramolecular cyclization of 1-azacyclononan-l-yl (Scheme 1) (72CJCH67). As is the case with alicyclic ethers, oxepane in the reaction with r-butoxy radical suffers abstraction of a hydrogen atom from the 2-position in the first reaction step (Scheme 2) (76TL439). 

Azocrown ethers pyrazoles, 5, 228 Azo dyes, 1, 328-331 colour and constitution, 1, 342 heterocyclic, 1, 325-326 Azo-hydrazone tautomerism, 1, 331, 334 Azoles acetic acids decarboxylation, 5, 92 acetoxymercurio reactions, 5, 107 acetyl... 

Quaternary ammonium compounds biocidal activity mechanism, 1, 401 toxicity, 1, 124 Quaternization heterocyclic compounds reviews, 1, 73 ( )-Quebrach amine synthesis, 1, 490 Queen substance synthesis, 1, 439 4, 777 Quercetin occurrence, 3, 878 pentamethyl ether photolysis, 3, 696 photooxidation, 3, 695 Quercetrin hydrolysis, 3, 878 Quinacetol sulfate as fungicide, 2, 514 Quinacridone, 2,9-dimethyl-, 1, 336 Quinacridone pigments, 1, 335-336 Quinacrine... 

A base induced rearratvgemenl by conversion ot aryl Iri- or tetra-haloethyl ethers Into o-hydroxyphenylalkynes and Into heterocyclic systems... 

The most versatile derivative from which the free base can be readily recovered is the picrate. This is very satisfactory for primary and secondary aliphatic amines and aromatic amines and is particularly so for heterocyclic bases. The amine, dissolv in water or alcohol, is treated with excess of a saturated solution of picric acid in water or alcohol, respectively, until separation of the picrate is complete. If separation does not occur, the solution is stirred vigorously and warmed for a few minutes, or diluted with a solvent in which the picrate is insoluble. Thus, a solution of the amine and picric acid in ethanol can be treated with petroleum ether to precipitate the picrate. Alternatively, the amine can be dissolved in alcohol and aqueous picric acid added. The picrate is filtered off, washed with water or ethanol and recrystallised from boiling water, ethanol, methanol, aqueous ethanol, methanol or chloroform. The solubility of picric acid in water and ethanol is 1.4 and 6.23 % respectively at 20°. 

The common impurities found in amines are nitro compounds (if prepared by reduction), the corresponding halides (if prepared from them) and the corresponding carbamate salts. Amines are dissolved in aqueous acid, the pH of the solution being at least three units below the pKg value of the base to ensure almost complete formation of the cation. They are extracted with diethyl ether to remove neutral impurities and to decompose the carbamate salts. The solution is then made strongly alkaline and the amines that separate are extracted into a suitable solvent (ether or toluene) or steam distilled. The latter process removes coloured impurities. Note that chloroform cannot be used as a solvent for primary amines because, in the presence of alkali, poisonous carbylamines (isocyanides) are formed. However, chloroform is a useful solvent for the extraction of heterocyclic bases. In this case it has the added advantage that while the extract is being freed from the chloroform most of the moisture is removed with the solvent. 

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