title: Diastereoselective [3+2] Annulation of Aromatic/Vinylic Amides with Bicyclic Alkenes through Cobalt-Catalyzed C-H Activation and Intramolecular Nucleophilic Addition.
abstract: A highly diastereoselective method for the synthesis of dihydroepoxybenzofluorenone derivatives from aromatic/vinylic amides and bicyclic alkenes is described. This new transformation proceeds through cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group. Transition-metal-catalyzed C-H activation reactions of secondary amides with alkenes usually lead to [4+2] or [4+1] annulation; to the best of our knowledge, this is the first time that a [3+2] cycloaddition is described in this context. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. Mechanistic studies imply that the C-H bond cleavage may be the rate-limiting step.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
authors.forename: Parthasarathy
authors.identifier: http://orcid.org/0000-0002-2483-7353
authors.initials: P
authors.lastname: Gandeepan
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
authors.forename: Pachaiyappan
authors.identifier: http://orcid.org/0000-0001-8079-0425
authors.initials: P
authors.lastname: Rajamalli
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan. chcheng@mx.nthu.edu.tw.
authors.forename: Chien-Hong
authors.identifier: http://orcid.org/0000-0003-3838-6845
authors.initials: CH
authors.lastname: Cheng
keywords: C−H activation; alkenes; amides; annulation; cobalt