Reaction of 3-azidoisoxazoles with active methylene compounds

3-Azidoisoxazoles react with various active methylene compounds (malononitrile, ethyl cyanoacetate and ethyl acetoacetate) in the presence of base to give hybrid isoxazole–triazole molecules in good to nearly quantitative yields. © 201

3,3-Diazidoenones-new types of highly reactive bis-azides. Preparation and synthetic transformations

The interaction of geminal dichlorovinylketones with sodium azide was investigated by NMR and DFT calculations. It was found that the corresponding geminal 3,3-diazidoenones are the resultant species. These highly reactive compounds can be trapped with cyclooctyne to form bis-triazolyl substituted enones. In the absence of a trapping agent, 3,3-diazidoenones do cyclize into 3-azidoisoxazoles with the elimination of molecular nitrogen. The versatile reactivity of the resultant azidoisoxazoles was demonstrated in reactions with phosphorus(iii) derivatives, Huisgen 1,3-dipolar cycloaddition and Dimroth cyclization to provide efficient access to a variety of valuable compounds. © 2019 the Partner Organisations

Synthesis of Azaheterocyclic Cymantrene Derivatives

The reduction of acetylcymantrene with sodium tetrahydridoborate gave cymantrenylethanol which was acylated with 4,5-dichloroisothiazole- and 5-(4-methylphenyl)isoxazole-3-carbonyl chlorides to obtain esters containing a 1,2-thia(oxa)zole fragment. The condensation of acetylcymantrene with 5-arylisoxazole-3- carbaldehydes, (5-arylisoxazol-3-yl)methoxybenzaldehydes (Ar = Ph, 4-Tol), and 4,5-dichloroisothiazole-3- carbaldehyde afforded the corresponding (E)-3-(azol-3-yl)-1-cymantrenylprop-2-en-1-ones. The resulting α,β- unsaturated ketones reacted with semicarbazide hydrochloride and thiosemicarbazide to produce substituted 4,5-dihydro-1H-pyrazole-1-carboxamides and -1-carbothioamides, and their reaction with hydroxylamine hydrochloride led to the formation of 4,5-dihydroisoxazoles containing cymantrene and 1,2-azole fragments. Heterocyclization of azolylcymantrenylpropenones with guanidine gave 2-aminopyrimidine derivatives, and dihydropyrimidine-2-thiones were obtained by their reaction with thiourea. © 2018, Pleiades Publishing, Ltd

Synthesis of Azaheterocyclic Cymantrene Derivatives

The reduction of acetylcymantrene with sodium tetrahydridoborate gave cymantrenylethanol which was acylated with 4,5-dichloroisothiazole- and 5-(4-methylphenyl)isoxazole-3-carbonyl chlorides to obtain esters containing a 1,2-thia(oxa)zole fragment. The condensation of acetylcymantrene with 5-arylisoxazole-3- carbaldehydes, (5-arylisoxazol-3-yl)methoxybenzaldehydes (Ar = Ph, 4-Tol), and 4,5-dichloroisothiazole-3- carbaldehyde afforded the corresponding (E)-3-(azol-3-yl)-1-cymantrenylprop-2-en-1-ones. The resulting α,β- unsaturated ketones reacted with semicarbazide hydrochloride and thiosemicarbazide to produce substituted 4,5-dihydro-1H-pyrazole-1-carboxamides and -1-carbothioamides, and their reaction with hydroxylamine hydrochloride led to the formation of 4,5-dihydroisoxazoles containing cymantrene and 1,2-azole fragments. Heterocyclization of azolylcymantrenylpropenones with guanidine gave 2-aminopyrimidine derivatives, and dihydropyrimidine-2-thiones were obtained by their reaction with thiourea. © 2018, Pleiades Publishing, Ltd