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Showing papers in "Journal of Heterocyclic Chemistry in 1990"


Journal ArticleDOI
TL;DR: In this article, the substitution of protonated heteroaromatic bases by nucleophilic carbon-centered radicals has been developed as one of the most general reactions in the heterocyclic series; its great interest results from the fact that it reproduces most of the numerous aspects of the Friedel-Crafts aromatic substitution, but with opposite reactivity and selectivity.

207 citations



Journal ArticleDOI
TL;DR: In this article, the Suzuki Pd(0)-catalyzed coupling between arylboronic acids and bromides or iodides in weakly alkaline medium was evaluated.

122 citations


Journal ArticleDOI
TL;DR: The cyclization of 5-amino-3-methylthiopyrazole-4-carbonitriles or 4-carboxamides 3a-j, which were prepared by the reaction of ketene dithioacetals with formamide or carbon disulfide, was described in this article.

93 citations


Journal ArticleDOI
TL;DR: In this paper, the reactions between 3-benzoyl-2-isothiocyanato-4,5,6,7-tetrahydrobenzo[b]thiophene and hydrazine or primary amines have been studied.

92 citations



Journal ArticleDOI
TL;DR: In this article, an aromatic aldehyde and bis(3-ethyl-4-methyl-2-pyrrolyl)-methane were obtained from acetonitrile in the presence of a catalytic amount of trichloroacetic acid, followed by p-chloranil oxidation.

61 citations


Journal ArticleDOI
TL;DR: Polarized ethylenes having both electron-donating (an amino or a methylthio group) and electron-accepting (cyano, carbamoyl, methyl ester) groups on the adjacent two olefinic carbon atoms were prepared by the condensation of S-alkylthioamidinium salts or methyl dithiocarboxylates with the corresponding active methylene compounds in good yields.

59 citations


Journal ArticleDOI
TL;DR: In this article, a one-pot synthetic approach to the novel 3a,4,5,6-tetrahydro[1,2,4]oxadiazolo[4, 5-a][1,5]benzodiazepine system is described.

58 citations



Journal ArticleDOI
TL;DR: The pyrazolo[3,4-d]pyrimidin-3-one congeners of guanosine, adenosine and inosine is described in this paper.

Journal ArticleDOI
TL;DR: In this paper, a 12% overall yield from 4,4′-dimethyl-2,2′-bipyridine (3) via a 5-step reaction sequence involving the intermediate 4, 4′-R2-2.2.

Journal ArticleDOI
TL;DR: In this paper, the relative esters of 4-substituted 2-amino-, 2-methyl- or 2-phenyl-5-pyrimidine carboxylic acids were obtained in moderate yields by reaction of the above dinucleophiles with ethyl 2,2-diformylacetate.

Journal ArticleDOI
TL;DR: Synthesis of several bis(4-arylthiosemicarbazido- 1, bis(2-arylamino-1,3,4thiadiazol-5-yl)- 5 and bis( 4-aryl-1.2,4-triazolin-3-thione-5yl)- 2 pentanes is described.

Journal ArticleDOI
TL;DR: In the presence of copper(I) chloride, the palladium catalyzed oxidation of methyl 2-ethenylbenzoates (2-ETHB) and 2-Ebenzamides has been studied.

Journal ArticleDOI
TL;DR: In this article, the synthesis of the title compounds 3 upon cyclodehydration with thionyl chloride of the corresponding bis-aroylhydrazides 2 is described and their spectral properties are examined.

Journal ArticleDOI
TL;DR: In this paper, the reaction of β-naphthylamine, dimedone and the appropriate aromatic aldehyde in ethanol gave 1,2,3,4,5,6-hexahydro-2,2-dimethyl-5-aryl-6-aza-9,10-benzophenanthren-4-ones, III, which upon treatement with chromic anhydride, yielded the corresponding tetrahydro derivatives, IV.

Journal ArticleDOI
TL;DR: In this paper, the reaction of ethyl 4,4,4 trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5-hydroxy-3-(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3-hydrox-5-(trifioromethemyl) pyrazole 4.

Journal ArticleDOI
TL;DR: In this article, a practical method for the preparation of 2-chloro-4,6-di(heteroaryl)pyrimidines and their 5-methyl homologues from readily available 2chloropyrimidine and 2chloro -5-methylpyrimidine, respectively, is described.


Journal ArticleDOI
TL;DR: In this article, the two structural isomers, 4 and 5, of 1-substituted-4-iminomethyl-1,2,3-triazoles are interconvertible when heated in dimethyl sulfoxide at 80°.

Journal ArticleDOI
TL;DR: In this article, 3,6-Dichloropyridazine was ortho-lithiated by lithium 2,2,6,6tetramethylpiperidide.

Journal ArticleDOI
TL;DR: In this article, three synthetic entries of functionalized 6-fluoro-7-substituted indole derivatives were developed in connection with the preparation of 7-fluororo-8-substantituted-1,3,4,9-tetrahydropyrano[3, 4-b]indole-1-acetic acid derivatives.

Journal ArticleDOI
TL;DR: In this article, the diazotisation of 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile and ethyl-2-amide-4.5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23

Journal ArticleDOI
TL;DR: In this paper, an efficient synthesis of 2-n-dodecylthio-4-phenylthiomethyl-1,3,4-thiadiazole-5-thione is described.

Journal ArticleDOI
TL;DR: In this paper, 2,4-disubstituted thiosemicarbazides were allowed to react with α-bromoacetophenone to give the anticipated 2,3-dihydro-6H-1,3, 4thiadiazines.

Journal ArticleDOI
TL;DR: In this article, a stereo-specific cycloaddition of 2,3-disubstituted oxiranes to heterocumulenes, including carbodiimides, isocyanates and carbon dioxide, is catalytically promoted by dialkyltin diiodide-hexamethylphosphoric triamide (HMPA) system, producing various five-membered heterocycles.

Journal ArticleDOI
TL;DR: In this article, the structure of the 4-Thiocarbamoyl-5-aminoisoxazole (4,3d) compound was definitively assigned by X-ray analysis.

Journal ArticleDOI
TL;DR: The reaction of pyridinium or isoquinolinium N-ylides with methoxy-substituted ethylenes gave the corresponding indolizine and pyrrolo[2,1-a]isoquinoline derivatives bearing acetyl, aroyl, cyano, ester group at the 1-position in one step as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the primary reaction products between dehydroacetic acid and p-chlorophenylhydrazine or 4-phenylthiazol-2-yl hydrazine are 4-acetylacetyl-5-hydroxypyrazoles.