Synthesis of Spiro[indole-3,3'-pyrrolidine]-2'-(thi)ones.

Spiro[indole-3,3'-pyrrolidine]-2'-ones were synthesized via one-pot chloroformylation-dearomatizing spirocyclization of tryptamine derivatives. Moreover, the "thio" equivalent spiro[indole-3,3'-pyrrolidine]-2'-thiones, for which the synthesis and properties were previously unreported, were synthesized. The procedures are easily implemented, have a broad scope, and are transition-metal-free and cheap. To demonstrate the utility of the synthetic methodology, the spiro[indole-3,3'-pyrrolidine]-2'-ones were converted into heterocyclic scaffolds, such as an optically active spiroindoline and spirooxindole.