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A group of noroxymorphone derivatives were subjected to Gewald reaction conditions to prepare their respective aminothieno products. In refluxing piperidine/ethanol, 1a–g reacted with elemental sulfur and malononitrile to produce 2a–g in high yields. Reactions took place in one pot and completed within 4–7 h and products precipitated spontaneously in the reaction mixtures. [ABSTRACT FROM AUTHOR]

A one-pot cyclocondensation of 1,3-dioxane-5-one (1) with malononitrile and aromatic aldehydes in aqueous sodium hydroxide under ultrasonic irradiation furnishes a series of pyrano[3,2-d][1,3]dioxin derivatives 3. Reactions are completed after a few minutes and the precipitated products are purified by simple crystallization from ethanol. The reaction with ethyl cyanoacetate instead of malononitrile gives the respective analogous products in high yields. [ABSTRACT FROM AUTHOR]

Various derivatives of thiopyrano[4,3-b]pyran structure are synthesized via a multicomponent procedure starting from tetrahydro-4H-thiopyran-4-one, aromatic aldehydes, and malononitrile. Reactions take place by the use of catalytic quantities of LiOH·H2O in one pot under ultrasonic conditions and in an ethanolic medium. Isolation of products occurs by spontaneous precipitation in reaction mixtures and no cumbersome and expensive chromatographic separations are needed. [ABSTRACT FROM AUTHOR]

A facile procedure is developed for one-pot synthesis of a new group of dicyanoanilines. Tetrahydro-4H-thiopyran-4-one,1, undergoes a pseudo four-component reaction with various aldehydes bearing different groups and two equivalents of malononitrile in aqueous media in the presence of triethylamine (Et3N). As a result, novel thiopyran-fused dicyanoanilines4are formed efficiently in the reaction mixtures in 90–97% yield within 9–12 h mixing at 40°C. Due to the polarity of the medium, products precipitate in the mixture spontaneously allowing for easy purification by recrystallization avoiding cumbersome chromatographic separations. Characterization of the products was performed by spectroscopic methods and, in one case, was further supported by X-ray crystallographic experiments. [ABSTRACT FROM AUTHOR]

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Catalytic quantities (2 mol%) of a complex of cobalt containing guanidine and 2,6-pyridinedicarboxylic acid ligands (PDAG-Co) were used for the efficient three-component Mannich reactions of tetrahydro-4-pyranone ( 1) with different aromatic aldehydes and aniline derivatives in a one-pot process. Reactions rapidly gave high yields of the corresponding three-substituted tetrahydro-4-pyranones at room temperature. Spectroscopic and X-ray analyses support the formation of anti diastereomers as the major or sole products of the reactions. [ABSTRACT FROM AUTHOR]

Abstract: A facile one-pot three-component condensation of terephthalic aldehyde with urea and fluorinated 1,3-dicarbonyl derivatives is developed using catalytic quantities of chlorotrimethylsilane at ambient temperature. As a consequence, efficient synthesis of novel trifluoromethyl derivatives of bis(tetrahydropyrimidinone)benzenes is observed within short time periods. The procedure is shown to be equally efficient when urea is replaced with thiourea or guanidine. [Copyright &y& Elsevier]