Cobalt(II)-Catalyzed C-H and N-H Functionalization of 1-Arylpyrazolidinones with Dioxazolones as Bifunctional Synthons.

Dioxazolone has been attractive as an important synthon for a direct C-H amidation through a nitrene intermediate or Curtius rearrangement to form the isocyanate. However, the combination of two reaction models of dioxazolone has not been reported. Herein, a cobalt-catalyzed C-H and N-H functionalization of 1-arylpyrazolidinones with dioxazolones was developed. The dioxazolones acted as an amidated and carboxamidated reagent. Three C-N bonds were formed in a "one-pot" manner, which promoted the requirement of synthetic diversity.

Rh(III)-Catalyzed Synthesis of Indazolo[2,3-a]quinolines: Vinylene Carbonate as C1 and C2 Building Blocks.

A rhodium-catalyzed cyclization of azobenzenes and vinylene carbonate via C-H bond activation to construct indazolo[2,3-a]quinolines has been developed. This protocol offers an efficient method for synthesis of the titled products in good yields with broad functional group tolerance. In this reaction, three C-C bonds and C-N bond are formed in one pot, and vinylene carbonate (VC) acts as C1 and C2 synthons as well as "vinylene transfer" agent and acylation reagent in the construction of target-fused heterocycles. Moreover, the products exhibit favorable fluorescence properties, which indicate their potential application as fluorescent materials and biosensors.