DMAP-Catalyzed [4+3] Spiroannulation of Pyrazolone-Derived Morita–Baylis–Hillman Carbonates with <i>N</i>-(<i>o</i>-Chloromethyl)aryl Amides to Forge Spiro[pyrazolone-azepine] Scaffolds

Abstract

A novel DMAP-catalyzed [4+3] spiroannulation of pyrazolone-derived Morita–Baylis–Hillman carbonates with N -( o -chloromethyl)aryl amides was developed. This reaction led to the assembly of medicinally relevant pyrazolone and azepine nuclei into a structurally new spirocyclic scaffold, and a diverse array of spiro[pyrazolone-azepine] products were afforded in good to excellent yields (up to 93%) with a wide substrate scope (23 examples) under mild conditions. Moreover, a gram-scale reaction and product transformations were conducted, which further increased the diversity of products.

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