Dictating the Reactivity of η3‑Oxoallyl Pd-Intermediate toward 5‑exo‑trig Cyclization: Access to Indano-spirooxindoles

A facile synthesis of indanone-fused spirooxindoles is disclosed by directing the reactivity of η3-oxoallyl Pd-intermediate toward 5-exo-trig mode of cyclization. The Pd-catalyzed reaction of the rationally designed starting material 3-arylidene oxindoles with isatin-derived tosylhydrazone afforded the spirooxindoles having all-carbon quaternary center through carbene migratory insertion followed by Heck-type cyclization sequence. The photophysical studies and DFT calculations were conducted to understand their electronic properties. Moreover, the synthesis of XEN 907 analogue is also featured by employing the present methodology.本研究报道了一种茚酮稠合螺环氧化吲哚的简便合成方法：通过调控η³-氧代烯丙基钯（η³-oxoallyl Pd）中间体的反应活性，使其以5-外向三轨型环化模式进行环化。将合理设计的起始原料3-芳亚甲基氧化吲哚与靛红衍生的对甲苯磺酰腙进行钯催化反应，经由卡宾迁移插入及后续的Heck型环化串联过程，得到了含有全碳季碳中心的螺环氧化吲哚产物。通过光物理性质研究与密度泛函理论（DFT）计算，对该类化合物的电子性质开展了系统研究与解析。此外，依托本方法还实现了XEN 907类似物的合成。