Cascade Reaction of Tryptamine-Derived Isocyanides with Nitrile Oxides: Construction of Oxazine Fused-Spiroindoline Derivatives.

A one-step cascade reaction of tryptamine-derived isocyanides with in situ generated nitrile oxides for the synthesis of fused spiroindolines was described. The desired products could be efficiently synthesized in moderate to good yields (42-87%). The protocol features mild conditions, wide substrate scope, and high efficiency.