Synthesis of Indenone-Fused Pyran Derivatives from Aryl Enaminones and Cyclopropenones through Unsymmetrical Relay C–H Bond Activation and Double C–C/C–O Bond Formation
Chun Yang, Bin Li, Xinying Zhang, Xuesen Fan
Abstract
Presented herein is a novel synthesis of indenone-fused pyran derivatives via the cascade reactions of aryl enaminones with cyclopropenones. The formation of products involves a one-pot cascade procedure consisting of aryl C–H bond and enamine C–H bond functionalization along with C–C bond cleavage of cyclopropenone and 1,3-rearrangement of the in situ-formed allylic alcohol moiety followed by intramolecular O-nucleophilic addition and Me 2 NH elimination. To our knowledge, this is the first synthesis of indenone-fused pyran derivatives via simultaneous formation of both indenone and pyran scaffolds through concurrent unsymmetrical relay C–H bond activation and double C–C/C–O bond formation. Moreover, the usefulness of this method is further showcased by its suitability for large-scale synthetic scenarios and diverse transformations of products.