Enantioselective Pallada‐Electrocatalyzed C−H Activation by Transient Directing Groups: Expedient Access to Helicenes

Abstract

Asymmetric pallada‐electrocatalyzed C−H olefinations were achieved through the synergistic cooperation with transient directing groups. The electrochemical, atroposelective C−H activations were realized with high position‐, diastereo‐, and enantio‐control under mild reaction conditions to obtain highly enantiomerically‐enriched biaryls and fluorinated N−C axially chiral scaffolds. Our strategy provided expedient access to, among others, novel chiral BINOLs, dicarboxylic acids and helicenes of value to asymmetric catalysis. Mechanistic studies by experiments and computation provided key insights into the catalyst's mode of action.

Evolution of High‐Valent Nickela‐Electrocatalyzed C−H Activation: From Cross(‐Electrophile)‐Couplings to Electrooxidative C−H Transformations

“…[61b] In consideration of the environment-friendly nature of nickela-electrocatalytic oxidations, further excitingd evelopments are expected in this rapidlye volving research arena, such as the direct use of renewable forms of energy, [62] C(sp 3 )À Ha ctivations, CÀHa lkylations, [63] or particularlye nantioselective electrochemical-transformations. [64]…”

Transient imine directing groups for the C–H functionalisation of aldehydes, ketones and amines: an update 2018–2020

“…Ackermann demonstrated the combination of an electrochemical approach with a transient C-H activation methodology to achieve an atroposelective alkenylation of biaryl systems (Scheme 11). 40 Good yields and high ees were obtained in most cases, with several biaryl and N-naphthyl pyrroles functioning well. Vinyl sulfones, phosphonates, amides and ketones all proceeded in good yields and excellent enantioselectivity.…”

Recent Advances in Asymmetric Catalytic Electrosynthesis

“…However, as the control reaction without current resulted in a product yield corresponding to more than two catalyst turnovers, it appears as if electricity is accelerating product formation rather than enabling it. Ackermann and co-workers demonstrated the first asymmetric electrooxidative C-H activation process using Pd-catalysis and L-tert-leucine as transient directing group to provide access to axially chiral biaryls (Scheme 9) [60]. In an undivided cell with graphite felt anode and Pt plate cathode and constant current at 60 • C, various aldehyde-substituted biaryls were alkenylated to form axially chiral products in good yields with excellent ee's (up to 99%) and high position-and diastereocontrol.…”