Divergent Access to Polycyclic Fluorenofuran Systems via Palladium-Catalyzed Cascade Furan-Participated Diels–Alder Cycloaddition Reactions
Shugao Zhu, Rui Zhang, Ting Xia, Rongjing Yu, Shihan Liu, Yu Lan, Ruwei Shen
Abstract
The Pd-catalyzed reaction of 1-(2-iodophenyl)-3-arylprop-2-yn-1-ones with benzene-tethered furan-ynes produces novel fused hexacyclic indenone-furan scaffolds, while the reaction with propargyl furfuryl ethers affords the pentacyclic indenone-spirodifuran system. The thiophene-containing alkynes also proceed by similar transformations. A mechanism involving the Pd-catalyzed coupling and propargylic Alder-ene reaction to generate the indenone-allene intermediate, followed by an intramolecular furan/thiophene-participated inverse electron-demand Diels-Alder reaction, is proposed.
Topics & Concepts
FuranAlleneChemistryIntramolecular forceThiopheneCycloadditionPropargylCatalysisDiels–Alder reactionPalladiumMedicinal chemistryOrganic chemistryCatalytic Alkyne ReactionsCyclopropane Reaction MechanismsCatalytic C–H Functionalization Methods