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1.
The cyclization of hydrazone dianions with diethyl oxalate afforded pyrazole-5-carboxylates. 相似文献
2.
A. V. Puchnin M. A. Bastrakov A. M. Starosotnikov S. V. Popkov S. A. Shevelev 《Russian Chemical Bulletin》2012,61(3):596-599
The previously unknown 3-R-1,5-dinitro-3-azabicyclo[3.3.1]nonanes fused to the pyrazole or thiazole rings were synthesized by the reductive cyclization of m-dinitroindazoles and benzothiazoles. The method is based on the reduction of carbon-carbon bonds in the benzene ring, which are activated by the meta-nitro groups, with NaBH4 followed by the Mannich reaction with formaldehyde and primary amines. 相似文献
3.
Sébastien Degorce Bénédicte DelouvriéPaul R.J. Davey Myriam DidelotHervé Germain Craig S. Harris Christine Lambert-van der Brempt Honorine LebraudGilles Ouvry 《Tetrahedron letters》2012,53(45):6078-6082
Access to the 1,5-disubstituted-1H-1,2,4-triazole-3-carboxamide motif is quite laborious and requires forcing conditions to effect the cyclocondensation step. Herein, we report an efficient and mild one-pot protocol to access this substructure in good chemical yields with high regiocontrol. 相似文献
4.
The cyclization of the dianions of diethyl 2-oxopropylphosphonate and of acetone with 1,1-diacylopropanes afforded hydroxyspiro[5.2]cyclooctenones which were transformed, by homo-Michael reactions with tetrabutylammonium halides, into various functionalized phenols or their dimers. 相似文献
5.
V. L. Gein T. M. Zamaraeva E. S. Volkova M. V. Dmitriev 《Russian Journal of Organic Chemistry》2016,52(5):730-733
Reaction of diethyl oxalylacetate sodium salt with aromatic aldehydes and urea led to the formation of diethyl 6-aryl-2-oxo-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates. 相似文献
6.
Katsushi Morimoto Toshiaki Sato Susumu Yamamoto Hiroshi Takeuchi 《Journal of heterocyclic chemistry》1997,34(2):537-540
Reactions of methyl pyrazole-4-carboxylates 4b-d with N-chlorosuccinimide under heating conditions without a solvent gave methyl 3,5-dichloro-1-methylpyrazole-4-carboxylate 4a in good yields. The reaction of 4a with sodium hydrosulfide led to a nucleophilic substitution on the 5-position regioselectively to afford methyl 3-chloro-1-methyl-5-mercaptopyrazole-4-carboxylate 6a, which was followed by oxidative chlorination and amination to obtain 3-chloro-1-methyl-5-sulfamoylpyrazole-4-carboxylate 2a. Finally, the reaction of 2a with phenyl 4,6-dimethoxypyrimidin-2-yl carbamate 7 provided methyl 3-chloro-5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate (halosulfuron-methyl) 1a promising herbicide in com. 相似文献
7.
Pranab Haldar 《Tetrahedron letters》2007,48(33):5855-5857
A one-pot method for the synthesis of substituted ethyl 3-hydroxyquinoxaline-2-carboxylates under solvent and catalyst free conditions has been developed. 相似文献
8.
9.
Dianions of chiral nitro imines (generated by a combination of LDA and s-BuLi) underwent diastereoselective alkylation with methyl, butyl, isopropyl, allyl, and methallyl iodides. In contrast to the behavior of simple metalloenamines, the most selective auxiliary contained no coordinating groups but did possess a large steric difference between the two substituents. The yield and selectivity of the alkylations were improved by the addition of HMPA or DMPU. The use of (S)-1-naphthylethylamine as the auxiliary afforded the R absolute configuration of the alkylation products. This stereochemical outcome could be rationalized by simple steric approach controlled alkylation in a conformationally fixed, internally coordinated dianion. A SAMP nitro hydrazone gave poorer yields and selectivities. 相似文献
10.
Improved procedures for the regioselective preparation of ethyl 1,5-diarylpyrazole-3-carboxylates are described. The new procedures utilize readily prepared lithium aroylpyruvate intermediates which, when combined with arylphenylhydrazine hydrochlorides form 1,5-diarylpyrazole-3-carboxylates regioselectively in good to excellent yield. 相似文献
11.
5-(2-Aminophenyl)isoxazoles are obtained in good yields by the reaction of 2-(trifluoromethyl)aniline with dilithio derivatives of oximes of acetone, 3-pentanone, propiophenone, and cyclohexanone. An analogous synthesis of a substituted isoxazole from 4-(trifluoromethyl)aniline and 3-pentanone oxime and the synthesis of a substituted pyrazole from 2-(trifluoromethyl)aniline and 3-pentanone hydrazone are less efficient. 相似文献
12.
Methyl propiolate, formaldehyde, and various acyclic amines were assembled in one-pot into a series of 1,5-diaza-2,6-cyclooctadiene-3,7-dicarboxylates in moderate to good yields. This multiple-component reaction benefits from operational simplicity as well as good material economy. 相似文献
13.
The condensation of thiazolidine-2, 4-dione, rhodanine, isorhodanine, 2-thiohydantoin, and pseudothiohydantoin with diethyl oxalate has given products which are azolidone-5-glyoxalic acids or their esters. In these compounds, the glyoxalic acid residue is readily replaced under the action of diazonium salts, aromatic nitroso compounds, and aromatic aldehydes with the formation of 5-arylazo-, 5-arylimino-, and 5-arylideneazolidones. 5-Arylidenerhodanines are also formed from 5-isopropylidene-and 5-(-acetyl--methylethylidene)rhodanines by their reaction with aromatic aldehydes and ketones. 相似文献
14.
The condensation of thiazolidine-2, 4-dione, rhodanine, isorhodanine, 2-thiohydantoin, and pseudothiohydantoin with diethyl oxalate has given products which are azolidone-5-glyoxalic acids or their esters. In these compounds, the glyoxalic acid residue is readily replaced under the action of diazonium salts, aromatic nitroso compounds, and aromatic aldehydes with the formation of 5-arylazo-, 5-arylimino-, and 5-arylideneazolidones. 5-Arylidenerhodanines are also formed from 5-isopropylidene-and 5-(β-acetyl-α-methylethylidene)rhodanines by their reaction with aromatic aldehydes and ketones. 相似文献
15.
Three-component condensation of diethyl 2-oxobutanedioate sodium salt with aromatic aldehydes and tetrazol-5-amine monohydrate afforded the corresponding diethyl 6-aryl-3,6-dihydrotetrazolo[1,5-a]pyrimidine-4,5-dicarboxylates. 相似文献
16.
Refluxing 2-hydrazinoperimidine (1) with excess amount of diethyl oxalate (2a) gave ethyl 1H-1,2,4-triazolo[4,3-a]perimidine-3-carboxylate (4a) in 84% yield. On the other hand, heating 1 with ethyl pyruvate (2b) in glacial acetic acid afforded 3-methyl-1,2,4-triazino[4,3-a]perimidin-4(1H)-one (6b) in 92% yield. Structures of the products were investigated by spectral and elemental analysis. 相似文献
17.
The reaction between perfluoroalkyl-Grignard or lithium compounds and diethyl carbonate has been investigated. Under appropriate conditions, symmetric or asymmetric ketones can be prepared. The reactions of the perfluoro- Grignard or lithium compounds with diethyl oxalate can yield keto-esters and symmetric or asymmetric ketones. 相似文献
18.
[reaction: see text] Enantiomerically pure 5-acetyl-3-amino-3,4-dihydro-2H-1-benzopyran and methyl 3-amino-3,4-dihydro-2H-1-benzopyran-5-carboxylate were successfully synthesized starting from d- or l-serine. The formation of the benzopyran ring involved a radical cyclization step. The enantiomeric purities of the final aminochroman derivatives were determined by capillary electrophoresis using beta-cyclodextrins as a chiral selector. 相似文献
19.
Five neutral platinum-based macrocycles incorporating cyclic oxocarbondianions, squarate and croconate and their acyclic analogue, oxalate, have been synthesized in 90-95% yield via self-assembly. The combination of the diplatinum molecular clip with all three dianions afforded molecular rectangles, whereas a platinum-based 60 degrees acceptor unit produced a supramolecular rhomboid with croconate ion but a triangle with squarate ion. In all cases, multinuclear NMR spectra were consistent with the formation of single highly symmetrical species. The three rectanglular and the rhomboid assemblies were characterized by single-crystal X-ray crystallography. The triangular species was characterized by FAB mass spectrometry. 相似文献