Synthesis of polycyclic spiroindolines <i>via</i> the cascade reaction of 3-(2-isocyanoethyl)indoles

Abstract

Tandem reactions of the yttrium(<b>iii</b>) catalyzed ring-opening reaction of 2,2'-diester aziridines with 3-(2-isocyanoethyl)indoles and the subsequent Friedel-Crafts/Mannich/desulfonylation were reported. A series of polycyclic spiroindolines containing tetrahydro-β-carbolines were obtained in moderate to excellent yields (56-92%) in one step under mild reaction conditions. A possible catalytic mechanism was also proposed.