冠醚酮酸和烷酸的合成

本文介绍了在PPA存在下，由B15C5和DB18C6同过量的二羧酸发生酰化作用，得到酮酸1a～e和3a～c。再把所得相应的酮酸1a～e和3a～c利用黄鸣龙法制得4'-(ω－羧基多亚甲基)苯并-15-冠-5(2a～e)和4',4'(5')-二(ω-羧基多亚甲基)二苯并-18-冠-6(4a～c)等一系列ω-冠醚酮酸。     

Photochemical chlorination of 2-trichloromethyl-1,3-dioxolane

The photochemical chlorination of 2-trichloromethyl-1,3-dioxolane proceeds only at the carbon atoms in the 4 and 5 positions. The structures of the resulting 2-trichloromethyl-4-chloro-and 2-trichloromethyl-4,5-dichloro-1,3-dioxolanes were proved by means of the IR spectra and chemical transformations.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1611–1613, December, 1973.     

Iron porphyrins anchored to a thermosensitive polymeric core-shell nanosphere as a thermotropic catalyst

A thermosensitive nanocatalyst was prepared in the reaction of water-soluble iron(III) porphyrins and thermosensitive polymeric nanospheres with a core-shell structure; its catalytic activity in cyclohexene oxidation by iodosylbenzene was dependent markedly on reaction temperatures in aqueous solution.     

A free-radical reaction of alkanoic acids with tetrachloroethylene

The di-tert-butyl peroxide-initiated free-radical reaction of C₃-C₆ alkanoic acids with tetrachloroethylene results in the formation of a mixture of isomeric (trichlorovinyl)alkanoic acids with the predominant isomer bearing the trichlorovinyl group at the (–1) position.Translated fromIzveshya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 1011–1013, April, 1996.     

Lipase catalysed kinetic resolutions of 3-aryl alkanoic acids

Hydrolase catalysed kinetic resolutions leading to a series of 3-aryl alkanoic acids (?94% ee) are described. Hydrolysis of the ethyl esters with a series of hydrolases was undertaken to identify biocatalysts that yield the corresponding acids with excellent enantiopurity in each case. Steric and electronic effects on the efficiency and enantioselectivity of the biocatalytic transformation were also explored.     

The critical properties of alkanoic acids using a low residence time flow method

The critical temperatures and pressures of the alkanoic acids containing up to eight carbon atoms have been measured using a low residence time flow method. Our data have been compared with literature data whenever possible and several inconsistencies in the literature data been resolved by the present work. In particular, our data show that literature methods which require an appreciable residence time are likely to yield poor estimates of the critical properties of alkanoic acids.     

Photochemical transformations of anthraquinone in polymeric alcohols

It is established that the photolysis of anthraquinone in both aerated and deoxygenated polymeric alcohols is not accompanied by reduction with the formation of anthrahydroquinone; as a result, an adduct of hydroxyanthracene and polymeric alcohol is formed.     

Synthesis of (1H-pyrrol-2-ylsulfanyl)alkanoic acids

(1-Benzyl-1H-pyrrol-2-ylsulfanyl)acetic acid, 2- and 3-(1-benzyl-1H-pyrrol-2-ylsulfanyl)propionic acids, 1,1′-[1,4-phenylenebis(methylene)]bis[(1H-pyrrol-2-ylsulfanyl)acetic acid], and 1,1′-(hexane-1,6-diyl)bis-[(1H-pyrrol-2-ylsulfanyl)acetic acid] were synthesized for the first time by reactions of 1-benzyl-1H-pyrrole, 1,1′-[1,4-phenylenebis(methylene)]bis(1H-pyrrole), and 1,1′-(hexane-1,6-diyl)bis(1H-pyrrole) with thiourea, iodine, and the corresponding halogen-substituted alkanoic acids. 1-(4-Nitrophenyl)-1H-pyrrole failed to react with thiourea and iodine.     

Diastereoselective solid-phase radical addition to oxime ether anchored to polymer support

Stereocontrol in radical reactions of oxime ether anchored to polymer support was studied. Highly diastereoselective solid-phase radical reaction was achieved by using triethylborane and diethylzinc as a radical initiator at low reaction temperature, providing a novel method for the synthesis of the alpha-amino acid derivatives with excellent diastereoselectivities.     

ESR studies of coordination state of divalent copper ions anchored to polymeric supports

ESR studies of the interaction of Cu(acac)₂ anchored to various polymeric supports with model ligands CO and Py have revealed the effect of these interactions on the coordination state of divalent copper ions.

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Cu(acac)₂, , CO (py). .

     

Silver-catalyzed decarboxylative chlorination of aliphatic carboxylic acids

Decarboxylative halogenation of carboxylic acids, the Hunsdiecker reaction, is one of the fundamental functional group transformations in organic chemistry. As the initial method requires the preparations of strictly anhydrous silver carboxylates, several modifications have been developed to simplify the procedures. However, these methods suffer from the use of highly toxic reagents, harsh reaction conditions, or limited scope of application. In addition, none is catalytic for aliphatic carboxylic acids. In this Article, we report the first catalytic Hunsdiecker reaction of aliphatic carboxylic acids. Thus, with the catalysis of Ag(Phen)(2)OTf, the reactions of carboxylic acids with t-butyl hypochlorite afforded the corresponding chlorodecarboxylation products in high yields under mild conditions. This method is not only efficient and general, but also chemoselective. Moreover, it exhibits remarkable functional group compatibility, making it of more practical value in organic synthesis. The mechanism of single electron transfer followed by chlorine atom transfer is proposed for the catalytic chlorodecarboxylation.     

Photochemical chlorination of nanodiamond and interaction of its modified surface with C-nucleophiles

A procedure for the photochemical chlorination of nanodiamond by molecular chlorine in the liquid phase was proposed. This process was studied quantitatively for the first time. Hydrolytic stability of the chlorinated nanodiamond surface in air and in a 0.05 M solution of NaOH was determined. A possibility of disintegration of the initial aggregates (<60 μm) to finer aggregates (<200 nm) was shown. The reactions of a series of C-nucleophiles (organolithium reagents, CN⁻ ion) with the chlorinated surface were carried out. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2130–2137, December, 2006.     

Solubilities of normal alkanoic acids by the UNIFAC group contribution method

The UNIFAC group contribution method was applied to predict solubilities of C₁₀–C₂₂ normal alkanoic acids in hydrocarbons, esters, ketones, and alcohols. The results were compared with the literature experimental data. It was found that taking into account dimerization of the acids improves considerably the prediction accuracy.     

A spin trap study of the one-step oxidative lactonization of alkanoic acids

Conclusions ESR spectroscopy and the spin trap method were used to show the intermediate formation of acyloxyl and 3-carboxyalkyl radicals in the direct oxidation of alkanoic acids to - lactones by the action of sodium peroxydisulfate.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2630–2633, November, 1986.     

Electrochemically-induced spirolactonization of alpha-(methoxyphenoxy)alkanoic acids into quinone ketals

Anodic oxidation of two series of alpha-(2)- and alpha-(4-methoxyphenoxy)alkanoic acids were studied both at the analytical and preparative scales in order to delineate mechanistic aspects of electrochemically induced spirolactonization and to develop synthetically useful orthoquinone bis- and monoketals. Although alpha-monomethylated carboxylic acids and acetic acid derivatives do not undergo any spiroannulation, alpha-dimethylated carboxylic acids furnished spirolactones in high yields. A gem-dimethyl effect is invoked to explain these differences in cyclization capacity. Electrooxidation conditions can be selected to furnish either quinone spirolactone bis- or monoketals. Chemoselective monohydrolysis of bisketals can also be accomplished in a stepwise fashion to furnish the corresponding spirolactone monoketals, but the ortho compound unfortunately dimerized in situ via a Diels-Alder process. An ECEC pathway is proposed to rationalize the observed spirolactonizations on the basis of cyclic voltammetry analyses.     

High temperature kinetics of the thermal decomposition of the lower alkanoic acids

The thermal decomposition of propanoic acid dilute in argon has beenstudied in a single-pulse shock tube over the temperature range of 1100-1500 K and over the pressure range of 14-18 atm. The decomposition kinetics have been satisfactorily computer modelled by means of afree radical mechanism involving H and OH chains. Recent single-pulse shock tube product analyses of acetic acid decomposition have been computer modelled using a free radical mechanism for decarboxylation coupled to a unimolecular dehydration reaction. A comparison between the thermal decomposition kinetics of the C₁? C₃ alkanoic acids is made. The present studies do notprovide evidence for the participation of transition states involving a pentavalent carbon atom in the pyrolyses of the lower alkanoic acids.     

Asymmetric aldol reactions on a soluble polymeric support

[reaction: see text] The combinatorial synthesis of small, nonpeptidic compounds is of increasing interest in current medicinal chemistry. To meet this demand, efficient entries, preferentially on polymeric supports, to pharmacologically interesting classes of compounds such as polyketides are necessary. Therefore, we have developed a synthetic protocol allowing for the asymmetric synthesis of diketides on the soluble support MeOPEG-5000. The strategy employed mainly allows for repeated aldolizations, thus providing access to functionalized polyketides of varying degree of oligomerization.