Vinyl derivatives of 2, 5-diaryl-1, 3,4-oxadiazoles

Vinyl derivatives of 2, 5-diaryl-1, 3, 4-oxadiazoles have been synthesized and some of their physical properties have been studied.     

Vinyl derivatives of 2, 5-diaryl-1, 3,4-oxadiazoles

Vinyl derivatives of 2, 5-diaryl-1, 3, 4-oxadiazoles have been synthesized and some of their physical properties have been studied.     

2, 5-Dialkyl-1, 3, 4-oxadiazoles

A single stage method has been developed for the preparation of 2, 5-dialky-1, 3, 4-oxadiazoles from aliphatic carboxylic acids, by boiling with hydrazine hydrochloride in phosphoryl chloride. A mechanism for the synthesis is suggested. The oxadiazoles are characterized, and the group refractivity of the 1, 3, 4-oxadiazole ring has been determined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1171–1175, September, 1970.     

2, 5-二取代基-1, 3, 4-恶二唑及恶二唑啉类化合物的合成

2-苯基-1,2,3-连三唑-4-甲酰肼(1)与芳酸在POCl~3催化下得到6种新的2-芳基-5-(2'-苯基-1',2',3'-连三唑-4'-基)-1,3,4-恶二唑(2)。1与羰基化合物缩合得到相应的酰腙(3),在Ac~2O作用下环化成2-取代基-3-乙酰基-5-(2'-苯基-1',2',3'-连三唑-4'-基)-1,3,4-恶二唑啉(4)。化合物的结构经元素分析,IR,^1HNMR和MS确证。     

Divergent pathway for the solid-phase conversion of aromatic acetylenes to carboxylic acids, alpha-ketocarboxylic acids, and methyl ketones

An efficient divergent pathway for the selective and quantitative solid-phase conversion of aromatic acetylenes to the corresponding carboxylic acids, alpha-keto-carboxylic acids, and methyl ketones is presented. A range of aromatic trimethylsilyl-protected acetylene building blocks was synthesized in excellent yields using a Sonogashira cross-coupling protocol and used in solid-phase synthesis on PEGA resin. Dependent on the selection of conditions, the same solid-supported alkyne could be quantitatively converted to an aromatic carboxylic acid, an aromatic alpha-ketocarboxylic acid, or an aromatic methyl ketone. The conversion to carboxylic acid involved an OsO4/NaIO4/HMTA-mediated oxidative cleavage of the silyl-deprotected alkyne to provide the aromatic carboxylate in excellent yield. The alpha-ketocarboxylic acids were obtained by direct treatment of the trimethylsilyl-protected alkyne with OsO4/NMO/HMTA, while the ketones were obtained by simple acid-mediated hydration of the alkyne using aqueous TFA. In general, all products were obtained in excellent purities, typically above 90%. In addition, it was shown that the alkyne-containing building blocks could easily be incorporated into resin-bound peptides and after chemoselective conversion of the alkyne the new functional groups could be used for further derivatization into peptidomimetic compounds.     

2-芳基-5-(5-苯基-2H-四唑-2-亚甲基)-1,3,4-噁二唑类化合物的研究

作者曾研究2-芳基-5-(2-苯基-4-喹啉基)-1,3,4-噁二唑类衍生物,并发现它们具有促进小麦发芽生长的功效。Juby和Shan等报道某些四唑类化合物具有消炎性     

Decarboxylative etherification of aromatic carboxylic acids

Decarboxylative Chan-Evans-Lam-type couplings are presented as a new strategy for the regiospecific construction of diaryl and alkyl aryl ethers starting from easily available aromatic carboxylic acids. They allow converting various aromatic carboxylate salts into the corresponding aryl ethers by reaction with alkyl orthosilicates or aryl borates, under aerobic conditions in the presence of silver carbonate as the decarboxylation catalyst and copper acetate as the cross-coupling catalyst.     

One-pot two-step conversion of aromatic carboxylic acids and esters to aromatic aldehydes via indium-catalyzed reductive thioacetalization and desulfurization

Described herein is that a new approach to a one-pot two-step conversion of aromatic carboxylic acids/esters to aromatic aldehydes, in which indium(III) iodide effectively catalyzes both the first reductive thioacetalization of carboxylic acids and a subsequent desulfurization of the in-situ formed thioacetal intermediates leading to aldehydes.     

Synthesis of 3-cyano-4, 6-diaryl-3, 4-dihydropyridine-2-thionks

3-Cyano-4, 6-diaryl-3, 4-dihydropyridine-2-thiones have been synthesized for the first time by the condensation of arylideneacetophenones or 1-piperidino-1-phenyl-2-benzoylethane with cyanothioacetamide and the 1, 1-dicyano-2-aryl-3-benzoylpropane with hydrogen sulfide in the presence of bases. It has been established by PMR spectroscopy that 3-cyano-3,4-dihydropyridine-2-thiones exist in solutions in the form of mixture of cis and trans isomers.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1515–1520, November, 1983.     

Conversion of 2-amino-5-R-phenyl-1,3,4-oxadiazoles into 3-R-phenyl-5-alkoxy-1,2,4-triazoles

2-Amino-5-R-phenyl-1,3,4-oxadiazoles have been shown to isomerize in alcoholic potassium hydroxide solution to 3-R-phenyl-5-alkoxy-1,2,4-triazoles. The dissociative ionization of 3-R-phenyl-5-alkoxy-1,2,4-triazoles and 3-R-phenyl-1,2,4-triazolin-5-ones has been examined. The mass spectra of the oxadiazoles have been compared with those of the triazoles.Translated from Khimiya Geterotslklicheskikh Soedinenii, No. 11, pp. 1553–1556, November, 1986.     

Transformation of 5,5-diaryl-4,5-dihydro-1,2,4-oxadiazoles to 4-arylquinazolines

The transformation of 5,5-diaryl-4,5-dihydro-1,2,4-oxadiazoles to 4-arylquinazolines in boiling acetic anhydride via acyclic 1-acetyloxy-4-aryl-1,3-diaza-1,3-butadienes is described.     

Direct conversion of saturated and unsaturated carboxylic acids into aldehydes by thexylbromoborane-dimethyl sulfide

Thexylbromoborane-dimethyl sulfide readily reduces aliphatic carboxylic acids, including α,β-unsaturated ones, to aldehydes in excellent yields. However, the yields of aromatic aldehydes vary with the substituents.     

Synthesis of N,6-diaryl-2-imino-4-methyl-3-cyano-1,2,3,6-tetrahydropyrimidine-5-carboxamides

Russian Journal of General Chemistry -     

Copper-catalyzed aerobic oxidative synthesis of aromatic carboxylic acids

A simple, practical and efficient copper-catalyzed method for synthesis of aromatic carboxylic acids has been developed. The protocol uses inexpensive CuI/L-proline as the catalyst/ligand, and readily available aryl halides and malononitrile as the starting materials, and the corresponding aromatic carboxylic acids were obtained in moderate to good yields. The method is of tolerance towards functional groups in the substrates.     

Cyclization of acetylenic derivatives of aromatic carboxylic acids

The Cu(I)-catalyzed intramolecular cyclization of 1-phenylethynyl-and 1-hexyn-1-yl-anthraquinone-2-carboxylic acid is a 6-endo-dig-addition, whereas the reaction for 1-(3-phenoxypropyn-1-yl)anthraquinone-2-carboxylic acid proceeds in a directionally nonspecific way. It is shown that the cyclization of vicinal acetylenic derivatives of aromatic carboxylic acids leads to the formation of the more stable of the possible cyclic structures.Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Novosibirsk State University, 630090 Novosibirsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2138–2146, September, 1992.     

In situ infrared spectroscopic analysis of the adsorption of aromatic carboxylic acids to TiO2, ZrO2, Al2O3, and Ta2O5 from aqueous solutions

In situ infrared spectroscopy has been used to investigate the adsorption of a range of simple aromatic carboxylic acids from aqueous solution to metal oxides. Thin films of TiO2, ZrO2, Al2O3 and Ta2O5 were prepared by evaporation of aqueous sols on single reflection ZnSe prisms. Benzoic acid adsorbed very strongly to ZrO2, in a bridging bidentate fashion, but showed only weak adsorption to TiO2 and Ta2O5. Substituted aromatic carboxylic acids; salicylic, phthalic and thiosalicylic, were found to adsorb to each metal oxide. Salicylic and phthalic acids adsorbed to the metal oxides via bidentate interactions, involving coordination through both carboxylate and substituent groups. Thiosalicylic acid adsorbed to the metal oxides as a bridging bidentate carboxylate with no coordination through the thiol substituent group.