关键词: 偕偶氮异氰酸酯, 关环, 重排, 2-氧代-1, 2, 4-三唑并[3, 2-d][1, 5]苯并氧氮杂

Abstract: Many [1,2,4]triazolobenzoheteroazepine derivatives show interesting biological activities. In this paper, the geminal arylazo isocyanato compounds 3 were prepared from chroman-4-ones in three steps, i.e. condensation with arylhydrazine, cycloaddition of the resulting hydrazone with HNCO, and oxidative ring cleavage by KMnO₄. Compounds 3 were allowed to react with HBF₄, producing the respective 3-spiro substituted 1-aryl-4,5-dihydro-5-oxo-3H-1,2,4-triazolium salts 4. The concurrent rearrangement of compound 4 with insertion of the nitrogen atom into the carbon skeleton provided, after the basic work-up, 2-oxo-[1,2,4]triazolo[3,2-d][1,5]benzoxazepines 5a—5h. An unambigous structutal proof was obtained from the X-ray diffraction analysis for compound 5h.

Key words: Geminal arylazo isocyanates, Ring closure, Rearrangement, 2-Oxo-[1,2,4]triazolo[3,2-d][1,5]benzoxazepines