Copper(I)-Catalyzed Intramolecular N- N Coupling of Cyclopropyl O-Acyl Ketoximes: Synthesis of Spiro-fused Pyrazolin-5-ones.

A convenient copper-catalyzed approach has been developed for the synthesis of substituted spiro-fused pyrazolin-5-ones from readily available cyclopropyl O-acyl ketoximes via an intramolecular NN bond formation reaction. These catalytic reactions proceed in excellent yields with a broad scope. [ABSTRACT FROM AUTHOR]