Synthesis of 3,4-Fused Pyrroles with Seven-Membered Carbocycles via Cascade C-C σ-Bond Cleavage/Intramolecular Cyclization Reactions

A novel tandem reaction involving amino-substituted ynones and cyclic carbonyls has been developed, efficiently synthesizing 3,4-fused pyrroles with seven-membered carbocycles by a one-pot method. This reaction proceeds through a cascade ring-expansion of cyclic carbonyls, followed by intramolecular cyclization reactions. This metal-free strategy enables the concurrent construction of the medium-sized ring and the pyrrole ring, exhibiting a high step economy.