title: Viability of 4,5-dihydro-1,2,3,4-oxatriazoles reinvestigated.
abstract: The first procedures to prepare 4-bromo-4-methylpentanal and 4-azido-4-methylpentanal are reported. The latter compound and also the parent 4-azidobutanal do not lead to 4,5-dihydro-1,2,3,4-oxatriazoles by intramolecular 1,3-dipolar cycloaddition, although it was claimed to be so in the literature. The NMR spectroscopic data of such heterocycles reported previously do not agree with those of similar substances and are incompatible with (13)C NMR spectroscopic chemical shifts calculated by quantum chemical methods in the presented work. These calculations show furthermore that the intramolecular cycloaddition of 4-azidobutanals to give the title compounds is strongly endothermic and thus most probably not possible.
authors.affiliation: Organic Chemistry, Chemnitz University of Technology, Strasse der Nationen 62, 09111 Chemnitz, Germany.
authors.forename: Samia
authors.initials: S
authors.lastname: Firdous
authors.forename: Klaus
authors.initials: K
authors.lastname: Banert
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Auer
mesh_terms: D001386:Azides / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D001386:Azides; D014230:Triazoles