Lactones dicarboxylic acid

The lactone dicarboxylic acid yielded the lactone anhydride upon treatment with acetic anhydride at elevated temperatures (160 °C), which is itself a readily... 

The benzoic acid derivative 457 is formed by the carbonylation of iodoben-zene in aqueous DMF (1 1) without using a phosphine ligand at room temperature and 1 atm[311]. As optimum conditions for the technical synthesis of the anthranilic acid derivative 458, it has been found that A-acetyl protection, which has a chelating effect, is important[312]. Phase-transfer catalysis is combined with the Pd-catalyzed carbonylation of halides[3l3]. Carbonylation of 1,1-dibromoalkenes in the presence of a phase-transfer catalyst gives the gem-inal dicarboxylic acid 459. Use of a polar solvent is important[314]. Interestingly, addition of trimethylsilyl chloride (2 equiv.) increased yield of the lactone 460 remarkabiy[3l5]. Formate esters as a CO source and NaOR are used for the carbonylation of aryl iodides under a nitrogen atmosphere without using CO[316]. Chlorobenzene coordinated by Cr(CO)j is carbonylated with ethyl formate[3l7]. 

Amino-4,6-dimethyl-3-oxo-3//-phenoxazine-l,9-dicarboxylic acid also named actinocin is the chromophor of the red antineoplastic chromopeptide aetinomyein D (formula A). Two cyclopenta-peptide lactone rings (amino acids L-threonine, D-valine, L-proline, sarcosine, and 7V-methyl-L-valine) are attached to the carboxy carbons of actinocin by two amide bonds involving the amino groups of threonine. 

The paraffin wax is oxidized by air in a liquid phase process at 110-130°C. Catalysts for this radical reaction are cobalt or manganese salts [54]. The quality of the obtained mixture of homologous carboxylic acids is impaired by numerous byproducts such as aldehydes, ketones, lactones, esters, dicarboxylic acids, and other compounds. These are formed despite a partial conversion of the paraffin and necessitate an expensive workup of the reaction product [50,55]. 

As the mechanism, a radical and a cationic pathway are conceivable (Eq. 31). The stereochemical results with rac- or mcjo-1,2-diphenyl succinic acid, both yield only trans-stilbene [321], and the formation of a tricyclic lactone 51 in the decarboxylation of norbornene dicarboxylic acid 50 (Eq. 32) [309] support a cation (path b, Eq. 31) rather than a biradical as intermediate (path a). 

Another approach to improve the color formation properties of Malachite Green lactone has been the introduction of nitrogen atoms into the phthalide ring. Thus, condensation of pyridine-2,3-dicarboxylic acid anhydride with dimethylaniline in the presence of zinc chloride has been shown54 to yield a mixture of the 4- and 7-azaphthalides 11 and 12. 

In vitro synthesis of polyesters using isolated enzymes as catalyst via non-biosynthetic pathways is reviewed. In most cases, lipase was used as catalyst and various monomer combinations, typically oxyacids or their esters, dicarboxylic acids or their derivatives/glycols, and lactones, afforded the polyesters. The enzymatic polymerization often proceeded under mild reaction conditions in comparison with chemical processes. By utilizing characteristic properties of lipases, regio- and enantioselective polymerizations proceeded to give functional polymers, most of which are difficult to synthesize by conventional methodologies. 

Reductions of anhydrides of monocarboxylic acids to alcohols are very rare but can be accomplished by complex hydrides [55, 99]. More frequent are reductions of cyclic anhydrides of dicarboxylic acids, which give lactones. Such reductions were carried out by catalytic hydrogenation, by complex hydrides and by metals. 

Other reagents used for the preparation of lactones from acid anhydrides are lithium borohydride [1019], lithium triethylborohydride (Superhydride ) [1019] and lithium tris sec-butyl)borohydride (L-Selectride ) [1019]. Of the three complex borohydrides the last one is most stereoselective in the reduction of 3-methylphthalic anhydride, 3-methoxyphthalic anhydride, and 1-methoxynaphthalene-2,3-dicarboxylic anhydride. It reduces the less sterically hindered carbonyl group with 85-90% stereoselectivity and is 83-91% yield [1019]. 

Heterocyclic secondary enamines and dicarboxylic acid dichlorides undergo complex, ring-size-dependent annulation reactions that, in the case of ester 238 and phthaloyl chloride (Scheme 57), lead to lactone-containing derivative 239 (02T2821). 

Miki and Hachiken reported a total synthesis of murrayaquinone A (107) using 4-benzyl-l-ferf-butyldimethylsiloxy-4fT-furo[3,4-f>]indole (854) as an indolo-2,3-quinodimethane equivalent for the Diels-Alder reaction with methyl acrylate (624). 4-Benzyl-3,4-dihydro-lfT-furo[3,4-f>]indol-l-one (853), the precursor for the 4H-furo[3,4-f>]indole (854), was prepared in five steps and 30% overall yield starting from dimethyl indole-2,3-dicarboxylate (851). Alkaline hydrolysis of 851 followed by N-benzylation of the dicarboxylic acid with benzyl bromide and sodium hydride in DMF, and treatment of the corresponding l-benzylindole-2,3-dicarboxylic acid with trifluoroacetic anhydride (TFAA) gave the anhydride 852. Reduction of 852 with sodium borohydride, followed by lactonization of the intermediate 2-hydroxy-methylindole-3-carboxylic acid with l-methyl-2-chloropyridinium iodide, led to the lactone 853. The lactone 853 was transformed to 4-benzyl-l-ferf-butyldimethylsiloxy-4H-furo[3,4- 7]indole 854 by a base-induced silylation. Without isolation, the... 

However, reactions of PAHs in ambient air to form more polar species (e.g., nitro-PAHs, ketones, quinones, lactones, and dicarboxylic acids) greatly enhance their solubilities in aqueous systems. This has major implications when one considers the distribution of PAHs, and their atmospherically formed PAC derivatives, through the air, water, and soil environments. These increases in solubility upon reaction are important not only from an environmental chemistry perspective but also in terms of possible impacts on public health and ecosystems, e.g., in both the exposure and the health effect... 

Cyclic tetrafluoro ethers are also the main or sole products of the sulfur tctrafluoridc fluorination of phthalic and pyromellitic acids, or their anhydrides, possessing two bulky ortho substituents (e.g., CF3. N02, Br. Cl or even Me). These substituents create steric crowding which pushes two neighboring carboxylic acid groups towards each other and forces cyclization acid anhydrides and difluoro lactones are the intermediates and they may be isolated from reactions carried out under sufficiently mild conditions. Thus, reaction of 3,6-bis(trifluoromcthyl)bcn-zcnc-1,2-dicarboxylic acid (4) with sulfur tctrafluoridc at ambient temperature results in dehydration to give exclusively the corresponding cyclic anhydride 5 at 60"C a mixture of the anhydride 5, 3,6-bis(trifluoromethyl)phthaloyI difluoride (6) and 3,3-difluoro-4,7-bis(trifluoro-methyl)isobenzofuran-l(3//)-one (7) is obtained, but at 200"C the final product, 1,1,3,3-tct-rafluoro-4,7-bis(trifluoromethyl)-l,3-dihydroisobenzofuran (8), is formed as the sole product.137... 

Aqueous alkali hydrolyzes lactones and the products, e.g. (287), are frequently unstable or recyclize, depending on other substituents present. Coumarin is hydrolyzed by dilute alkali first to the yellow cis acid (coumarinic acid) salt (288) which recyclizes to coumarin on acidification but when heated with alkali isomerizes to the trans acid (coumaric acid) salt (289). When it is desirable to identify the hydrolytic product of such a reaction it is better to incorporate a methylating agent so that the reverse reaction cannot then occur. Hot aqueous alkali converts methyl 3-bromocoumalate (290) into furan-2,4-dicarboxylic acid (73JCS(Pl)ll30). 

As a first approach to the synthesis of nagilactone 296, a norditer-penoid isolated from Podocarpaceae, which inhibit the expansion and mitosis of plant cells, an intramolecular Diels-Alder reaction of allene 1,3-dicarboxylic acid esters was used. The cyclization of 297 afforded the 8-lactone 298, rather than the y-lactone 299 [85JCS(P1)747]. 

Large number of dicarboxylic acids, keto-acids and/or lactones indicated severe degradation of the polyethylene matrix [37, 38, 95]. Dicarboxylic acids were the most abundant products formed during photo-oxidation and their amount increased especially after long irradiation times, i.e. in severely degraded samples [96]. The relationship between the degree of oxidation/ degradation in the polymer matrix and the amount of dicarboxylic acids... 

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