The Reaction of Nitrile Oxide-Quinone Cycloadducts. III. Reinvestigation of the Base-Induced Isomerization of the 1 : 1 -C=C-Adducts of Aromatic Nitrile Oxides with 2,5- and 2,6-Dialkyl-Substituted<i>p</i>-Benzoquinones
作者:Takashi Mukawa、Yukihiko Inoue、Shinsaku Shiraishi
DOI:10.1246/bcsj.72.2549
日期:1999.11
The structure of the product obtained by the base-induced isomerization of the 1,3-dipolar cycloadduct of 2,5-di-t-butyl-p-benzoquinone with 2,6-dichlorobenzonitrile oxide was determined by X-ray analysis. The t-butyl group at the bridgehead position of the 1,3-dipolar cycloadduct migrated to the neighboring carbonyl carbon atom. This base-induced rearrangement took place with a bulky group, i. e., Et, i-Pr, t-Bu, and Bn at the bridgehead position of nitrile oxide-quinone cycloadducts in an alcoholic media. The driving force of this reaction is considered to be due to stabilization by aromatization from isoxazoline derivatives to isoxazole-fused p-quinol derivatives.
通过X射线分析确定了2,5-二-叔丁基-p-苯醌与2,6-二氯苯腈氧化物的1,3-极性环加成物在碱引发异构化后的产物结构。1,3-极性环加成物中桥头位置的叔丁基团迁移至相邻的羰基碳原子。这种碱引发的重排在含有庞大取代基(即乙基、异丙基、叔丁基和苄基)的腈氧化物-醌环加成物在醇介质中发生。这一反应的驱动力被认为是由于从异噁唑啉衍生物到异噁唑融合p-喹啉衍生物的芳构化稳定作用。