Catalytic System‐Controlled Divergent Reaction Strategies for the Construction of Diversified Spiropyrazolone Skeletons from Pyrazolidinones and Diazopyrazolones

Abstract

Ac atalytic system-controlled divergent reaction strategy was here reported to construct four types of intriguing spiroheterocyclic skeletons from simple and readily available starting materials via ap recise chemical bond activation/[n + 1] annulation cascade.T he tetraazaspiroheterocyclic and trizazspiroheterocyclic scaffolds could be independently constructed by aselective NÀNbond activation/[n + 1] annulation cascade,aC(sp 2 )-H activation/[4+ +1] annulation and an ovel tandem C(sp 2 )-H/C(sp 3 )ÀHbond activation/[4+ +1] annulation strategy,a long with ab road scope of substrates,m oderate to excellent yields and valuable transformations.M ore importantly,inthese transformations,weare the first time to capture aN À Nb ond activation and aC (sp 3 ) À Hb ond activation of pyrazolidinones under different catalytic system. Scheme 1. Previous work and this work.