Synthesis of 6-aryl-1,6-dihydrodipyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>:4,3-<Emphasis Type="Italic">c</Emphasis>]pyridines

6-Azido-1H-pyrazolo[3,4-b]pyridino-5-carbaldehydes react with aromatic amines to give the corresponding N-arylimines which cyclize on heating in boiling toluene to give 6-aryl-1,6-dihydrodipyrazolo[3,4-b:4,3-e]pyridines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, 1717–1722, November, 2004.     

1-Alkoxy-7-hydroxy-1,3-dihydrofuro[3,4-<Emphasis Type="Italic">c</Emphasis>]pyridinium Salts

New salt structures have been synthesized from pyridoxal and various organic and inorganic acids.     

Alternative Routes to the Pyrazolo[4,3-<Emphasis Type="Italic">e</Emphasis>][1,2,4]triazolo-[1,5-<Emphasis Type="Italic">c</Emphasis>]pyrimidine System

Formimidic acid esters derived from 1-substituted 5-aminopyrazole-4-carbonitriles reacted with carboxylic acid hydrazides on heating to give 2,7-disubstituted pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives as a result of double heterocyclization. The same compounds were obtained by thermal recyclization of 1-aroyl-2-(1-R-pyrazolo[3,4-d]pyrimidin-4-yl)hydrazines.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 934–938.Original Russian Text Copyright © 2005 by Tyurin, Vorob’ev, Minyaeva, Krasnikov, Mezheritskii.     

Synthesis of a new hetrocyclic system 7,8-dihydroimidazo[1,2-<Emphasis Type="Italic">c</Emphasis>][1,3]oxazolo[4,5-<Emphasis Type="Italic">e</Emphasis>]pyrimidine

2-(Acylaminocyanomethylene)imidazolidines are formed on interacting 2-acylamino-3,3-dichloro-acrylonitriles with ethylenediamine. The former are converted into new derivatives of oxazolo-[4,5-e]pyrimidine on treatment with trifluoroacetic acid, and then with triethyl orthoformate.     

Synthesis of 1,4-Dihydropyrano[2,3-<Emphasis Type="Italic">c</Emphasis>]pyrazole Derivatives

In reaction of 2-(2-thienyl)- and 2-(2-furyl)acrylonitriles with 3-methyl-1-phenyl-5-pyrazolone in the presence of basic catalysts 4-thienyl- and 4-furyl derivatives of 3,5-dimethyl-1,7-diphenyl-4,8-dihydropyrano-[2,3-c, 5,6-c]dipyrazole were obtained.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 756–758.Original Russian Text Copyright © 2005 by Vasyun’kina, Bykova, Plotkin, Ramsh.     

Facile synthesis of 6-hetaryl[1,2,4]triazolo[3,4-<Emphasis Type="Italic">b</Emphasis>][1,3,4]thiadiazoles and 7-hetaryl[1,3,4]thiadiazolo[2,3-<Emphasis Type="Italic">c</Emphasis>][1,2,4]triazines with fungicidal activity

Condensation of 4-amino-4H-1,2,4-triazole-3-thiol and 4-amino-6-methyl-3-sulfanyl-1,2,4-triazin-5(4H)-one with ethyl cyanoacetate gave ethyl [1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-6-ylacetate and ethyl 3-methyl-4-oxo-4H-[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-7-ylacetate, respectively. Reactions of the condensation products with 1,3-diphenylprop-2-en-1-one, aromatic aldehydes, and carbon disulfide or N,N-dimethylformamide dimethyl acetal (followed by treatment with hydrazine hydrate) gave the corresponding 6-hetaryl-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles and 7-hetaryl-3-methyl-4H-[1,3,4]thiadiazolo[2,3-c][1,2,4]triazin-4-ones. Preliminary tests revealed fungicidal activity of the pyrazolyl-substituted derivatives. Published in Russian in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 12, pp. 1813–1818. The text was submitted by the authors in English.     

A convenient method for the synthesis of 1-R-1,2,3,4-tetrahydrobenzothieno-[2,3-<Emphasis Type="Italic">c</Emphasis>]pyridine derivatives

New 1-R-2-methyl-1,2,3,4-tetrahydrobenzothieno[2,3-c]pyridine derivatives have been obtained by cyclization of 2-(1-benzothiophen-3-yl)ethylamines with aromatic and heteroaromatic aldehydes in the presence of triisopropylchlorosilane.     

2-Alkyl-4-oxohexahydropyrimido[4,5-<Emphasis Type="Italic">d</Emphasis>]- and -[5,4-<Emphasis Type="Italic">d</Emphasis>]azocines

It has been established that 2-R-4-oxotetrahydropyrido[4,3-d]pyrimidines, under the action of activated alkynes in methanol, form a mixture of 2-R-4-oxohexahydropyrimido[4,5-d]azocines and products of decomposition of the tetrahydropyridine ring, the 2-R-5-methoxymethyl-4-oxo-6-vinylaminoethyl-pyrimidines. Tetrahydropyrido[3,4-d]pyrimidine, isomeric at the junction of the pyrimidine and tetrahydropyridine rings, forms only the corresponding pyrimido[5,4-d]azocine, the product of expansion, under the action of methyl propiolate.