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.