Synthesis of Tetracyclic Benzoxazolo-indol-3-ones from Isatogens and Arynes through a [3 + 2]-Cycloaddition and Skeletal Reorganization

The construction of an unprecedented tetracyclic benzoxazolo-indol-3-one
scaffold has been executed through the [3 + 2]-cycloaddition of isatogens
with arynes. The initially formed benzisoxazolo-indol-3-one intermediate
undergoes a skeletal reorganization through a 1,3-sigmatropic shift/retro-Mannich
reaction with the net formation of one C–N and two C–O
bonds. The Lewis acid-catalyzed allylation of some of the resulting
benzoxazolo-indol-3-ones resulted in oxazepino-indolones with promising
photophysical properties.

本研究成功构建了一种前所未有的四环苯并氧杂唑咯并吲哚-3-酮骨架，该骨架通过异喹啉与炔烃之间的[3+2]环加成反应得以实现。最初形成的苯并氧杂唑咯并吲哚-3-酮中间体通过1,3-σ-重排/逆曼尼希反应进行骨架重排，最终形成了一个C-N键和两个C-O键。一些生成的苯并氧杂唑咯并吲哚-3-酮在路易斯酸催化下进行烯丙基化反应，得到了具有良好光物理性质的噁唑啉并吲哚。