Rh(III)-Catalyzed meta-C–H Olefination Directed by a Nitrile Template

Abstract

A range of Rh(III)-catalyzed ortho-C-H functionalizations have been developed; however, extension of this reactivity to remote C-H functionalizations through large-ring rhodacyclic intermediates has yet to be demonstrated. Herein we report the first example of the use of a U-shaped nitrile template to direct Rh(III)-catalyzed remote meta-C-H activation via a postulated 12-membered macrocyclic intermediate. Because the ligands used for Rh(III) catalysts are significantly different from those of Pd(II) catalysts, this offers new opportunities for future development of ligand-promoted meta-C-H activation reactions.

Accessing Remote meta‐ and para‐C(sp2)−H Bonds with Covalently Attached Directing Groups

“…[23] Ap reviously reported Ushaped nitrile-based template played ap ivotal role in reaching the distal meta-position, and the mechanism is proposed to proceed through the formation of a12-membered rhodacycle (Scheme 12). [23] Ap reviously reported Ushaped nitrile-based template played ap ivotal role in reaching the distal meta-position, and the mechanism is proposed to proceed through the formation of a12-membered rhodacycle (Scheme 12).…”

Rhodium‐Catalyzed C(sp2)‐ or C(sp3)−H Bond Functionalization Assisted by Removable Directing Groups

“…[146] The presence of an easily removable acetate group at the gposition of the alkene is required to promote the b-OAc elimination and lead to the formation of the allylated product, which subsequently isomerized to 132.S imilarly,a ne fficient method for the Rh-catalyzed vinylation of benzamide using vinyl acetate as av inyl source was reported by Otley and Ellman (Scheme 41 d). [148] This represents the first example of aR h III -catalyzed metaalkenylation reaction which proceeds via a1 2-membered macrocyclic intermediate.The use of Cu(OCOCF 3 ) 2 ·x H 2 Oas an oxidant is essential for the success of the reaction. In this regard, Rh-catalyzed reactions remain underdeveloped.…”

“…Yu and co-workers recently reported the design of an itrile-based U-shaped template for use in the meta-CÀHalkenylation of amide 134 with various alkenes in the presence of ar hodium catalyst (Scheme 42). [148] This represents the first example of aR h III -catalyzed metaalkenylation reaction which proceeds via a1 2-membered macrocyclic intermediate.The use of Cu(OCOCF 3 ) 2 ·x H 2 Oas an oxidant is essential for the success of the reaction.…”

Zugang zu meta‐ und para‐C(sp2)‐H‐Bindungen mithilfe kovalent gebundener dirigierender Gruppen

“…Des Weiteren wurde gefunden, dass auch Rhodium mit dem cyclophanartigen Übergangszustand kompatibel ist. Die ersten Studien in diese Richtung unternahmen Yu und Mitarbeiter, die die erste rhodiumkatalysierte Olefinierung mithilfe einer carbonylverbrückten dirigierenden Gruppe beschrieben . Ein zuvor veröffentlichtes U‐förmiges nitrilbasiertes Templat spielte eine zentrale Rolle, um die distale meta ‐Position zu erreichen, und für den Mechanismus wird die Bildung eines 12‐gliedrigen Rhodacyclus vorgeschlagen (Schema ).…”