Thermisch und photochemisch induzierte intramolekulare, 1,3-dipolare Cycloadditionen von 5-(2-Allyloxyphenyl)-2-phenyltetrazol. Vorläufige Mitteilung. 54 Mitteilung über Photoreaktionen

Thermal and Photochemically Induced Interamolecular 1,3-Dipolar Cycloaddition Reactions of 5-(2-Allyloxyphenyl)-2-phenyltetrazole The title compound 5 is easily obtained by a recently described procedure (Scheme 2). The tetrazole 5 reacts at 165–170° or on irradiation at room temperature to yield 2-phenyl-3,3a-dihydrochromano4,3-c]pyrazole ( 7 , Scheme 3), which probably arises by intramolecular 3+2]-cycloaddition of the intermediate nitrilimine. Dehydrogenation of 7 with chloranil leads to 2-phenylchromano4,3-c]pyrazole ( 8 , Scheme 3).