Nickel‐Catalyzed Conversion of Enol Triflates into Alkenyl Halides

Abstract

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Electrochemical Nozaki–Hiyama–Kishi Coupling: Scope, Applications, and Mechanism

“…While we cannot yet assign the nature of this redox-active species, the influence of Ni(II) on the redox behavior suggests the presence of a potential interaction between the two metal species during electrocatalysis, which is in accord with prior electrochemical studies. 16 Introduction of Cp2ZrCl2 and alkyl aldehyde 1 to the mixture of Cr(III) and Ni(II) did not…”

“…A summation of this study (for a more extensive summary, see SI (maybe add a page number?) is outlined in Table 1 (entries [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The use of Cp2ZrCl2 (0.5 equiv) was found to be superior to other common oxophilic additives such as silyl chlorides (entries 5 and 6).…”

“…The Ni and Cr sources also played a vital role in reaction efficiency with NiCl2•glyme and CrCl2 proving optimal (entries 11 -13). Electrochemically, an inexpensive Al-based sacrificial anode and Ni-foam cathode provided higher yield and both the electrolyte (TBAB) and current settings (constant potential, undivided cell, no reference electrode) were optimum (entries [14][15][16][17][18]. With a concrete set of conditions in hand, the scope of e-NHK was evaluated as depicted in Table 2 with direct comparison in nearly all cases to past precedent (Tanaka, Table 1, entry 4).…”

“…To further elucidate the e-NHK electron transfer processes and support the critical steps of the proposed mechanism, cyclic voltammetry (CV) and UV-vis spectroelectrochemistry were employed. Previous work by Berkessel and coworkers demonstrated the utility of both of these electroanalytical techniques in characterizing species relevant to NHK chemistry; 16 thus, we were inspired to apply this approach to examine the e-NHK. To confirm whether or not the e-NHK had voltammetry consistent with an electrocatalytic mechanism, we performed a series of analytical CV measurements.…”

“…12 Alkenyl bromides S20 and S21 were prepared according to a procedure reported by Reisman and coworkers. 16 Alkenyl bromide S22 was prepared according to a procedure reported by Pattenden and coworkers. 17 Alkenyl bromide S23 was prepared according to a procedure reported by Chakraborty and coworkers.…”