Rhodium‐Catalyzed C−H Activation/Annulation of <i>N</i>‐Aryl‐pyrazolidinones with Vinylene Carbonate

Abstract

Abstract A rhodium‐catalyzed C−H activation/annulation of N ‐aryl‐pyrazolidinones with vinylene carbonate was developed. The utilization of vinylene carbonate as the acetylene surrogate furnished the successful construction of non‐substituted 5,6‐pyrazolo[1,2‐ a ]cinnoline derivatives, which are difficult to synthesize through other procedures. In this work, a series of variously substituted pyrazolo[1,2‐ a ]cinnolines were obtained in yields up to 98 % with broad substrate scope and excellent selectivity. Moreover, external oxidants were not required in this protocol with H 2 O and CO 2 as the clean by‐products.

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