A Light-Induced Vinylogous Nazarov-Type Cyclization

The first examples
of a photochemically induced vinylogous Nazarov-type
cyclization forming a cycloheptadienone core are described. The reaction
can be included in a three-step cascade consisting of a photochemical
isoxazole–azirine ring contraction, cobalt­(II)-catalyzed ring
expansion, and the photochemical cyclization. Furthermore, the first
representative of the hitherto unknown 1-azatricyclo­[2.2.0.02,6]­hexanes has been identified as a side product of
the azirine formation.

本文首次报道了通过光诱导插烯Nazarov型环化反应构建环庚二烯酮核心骨架的首例实例。该反应可纳入由三步组成的级联反应体系：光诱导异噁唑-氮丙环环收缩、二价钴催化的环扩环反应，以及光诱导环化反应。此外，本研究首次鉴定出此前尚未见报道的1-氮杂三环[2.2.0.02,6]己烷（1-azatricyclo[2.2.0.02,6]hexanes）类化合物，其可作为氮丙环生成过程中的副产物。