Reaction cascades initiated by nucleophilic attack of heteropentalene mesomeric betaine and nitrogen-rich mesoionic tetrazolium-5-amides on electron-deficient unsaturated compounds. Synthesis of novel heterocyclic systems.
The reactions of heteropentalene mesomeric betaine 1 and nitrogen-rich mesoionic tetrazolium-5-amides 4, 11 and 16-18 with electron-deficient unsaturated compounds have been studied. Novel heterocyclic systems, tetrazolo[4,5-a][1,7]benzodiazonine inner salt 2 and 3-oxo-3,7-dihydro-2H-pyrazolo[3,4-b]pyridine 5, have been synthesized by the reactions of dimethyl acetylenedicarboxylate with 1 and tetrazolium-5-anilide 4, respectively, and fully characterized by X-ray crystallography. It has been found that the reactions of other tetrazolium-5-amides are also initiated by the nucleophilic addition of the electron-rich amide nitrogen to the electron-deficient unsaturated compounds.
Diethyl 2-Aryl-3-cyanopropene-1,1-dicarboxylates: New Versatile Precursors in Heterocyclic Synthesis
Summary. An expeditious synthetic route for the title precursor is reported. It provides access to a variety of polyfunctionally substituted pyridines, pyridazines, pyrazolopyridines, thiophenes, and thienopyridines.Zusammenfassung. Eine einfache Synthese zur Darstellung des im Titel genannten Synthons wird beschrieben. Es vermittelt den Zugang zu polyfunktionell substituierten Pyridinen, Pyridazinen, Pyrazolopyridinen, Thiophenen und Thienopyridinen.
Azidinium-Salze. 23. Mitteilung. Photolyse heterocylischer Azidinium-Salze†
Photolysis of Heterocyclic Azidinium Salts 
 
 
 
The photochemistry of some azidinium salts was investigated. Their photolusis led to a large variety of products which were isolated and identified. Reaction mechanisms involving singlet and triplet nitrene intermediates are discussed to explain the product formation.