Ni-Catalyzed Borylation of Aryl Fluorides via C–F Cleavage

Abstract

A Ni-catalyzed borylation via C-F activation is described. This protocol is distinguished by a wide scope, including unactivated fluoroarenes, without compromising its efficiency and scalability, thus representing a significant step-forward towards the implementation of C-F activation protocols.Metal-catalyzed cross-coupling reactions of organic halides have become indispensable tools in modern synthetic chemistry.

Nickel/NHC‐Catalyzed Asymmetric C−H Alkylation of Fluoroarenes with Alkenes: Synthesis of Enantioenriched Fluorotetralins

“…Interestingly,n either isomers originating from alkene chain-walking isomerization nor exo-cyclized products were observed. We rationalized that abulky NHC on Ni could both accelerate the reductive elimination step to avoid isomerization and favor the endo-cyclization pathway for steric reasons.R emarkably,a lthough structurally similar NHC-stabilized Ni 0 complexes were reported to activate CÀ Fb onds over CÀHb onds in polyfluoroarenes, [15,16] no CÀF bonds cleavage was observed in the current system. We reasoned that our bulky NHC favors the formation of active monomeric Ni/NHC catalyst [22b] thus facilitating C À Hb ond activation instead.…”

“…[8] Ty pically,t etralin systems are synthesized through Friedel-Crafts type cyclization of aryl derivatives [9] or hydrogenation of naphthalene derivatives. [14] Second, selective activation of CÀHbonds over multiple CÀFb onds are required, although experimental [15] and computational [16] studies have suggested that Ni 0 complex exclusively favor oxidative addition into CÀFbonds instead of C À Hb onds in polyfluoroarenes. To our knowledge,t here are no general catalytic methods for the asymmetric synthesis of unfunctionalized fluorotetralins.Inthis context, we surmised that aN i-catalyzed asymmetric C À Ha lkylation of easily available alkene tethered fluoroarenes by an intramolecular hydroarylation might provide an efficient construction of chiral fluorotetralin derivatives (Scheme 1C).…”

“…[10] However,t hese two methods are not applicable to chiral fluorotetralin synthesis due to the challenges associated with chemo-, regio-, and stereocontrol and the facile hydrodefluorination side reaction [11] (Scheme 1A,B). [14] Second, selective activation of CÀHbonds over multiple CÀFb onds are required, although experimental [15] and computational [16] studies have suggested that Ni 0 complex exclusively favor oxidative addition into CÀFbonds instead of C À Hb onds in polyfluoroarenes. [12,13] However, we noted that several daunting challenges exist in this strategy.F irst, the competitive alkene isomerization through af acile Ni-promoted chain-walking process needs to be suppressed.…”

“…[12,13] However, we noted that several daunting challenges exist in this strategy.F irst, the competitive alkene isomerization through af acile Ni-promoted chain-walking process needs to be suppressed. [14] Second, selective activation of CÀHbonds over multiple CÀFb onds are required, although experimental [15] and computational [16] studies have suggested that Ni 0 complex exclusively favor oxidative addition into CÀFbonds instead of C À Hb onds in polyfluoroarenes. [17] Third, polyfluoroarylmetal bonds are particularly strong and unreactive.…”

Nickel‐Catalyzed Arylboration of Alkenylarenes: Synthesis of Boron‐Substituted Quaternary Carbons and Regiodivergent Reactions

“…Zuschriften coupling with vinyl fluorides is slow at ambient temperatures, [15,16] it is suggested that the product formation occurs via 1,2-elimination of the corresponding alkyl-[Ni]-complex. [17] With respect to the mechanistic proposal for the reaction in toluene,i tw as observed that use of a-methyl styrene (72)l ed to products resulting from aH eck-type reaction (74)and hydroarylation (75).…”