Electrochemically driven cross-electrophile coupling of alkyl halides

Abstract

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Boryl Radicals Enabled a Three-Step Sequence to Assemble All-Carbon Quaternary Centers from Activated Trichloromethyl Groups

“…As an alternative, a straightforward three-step process that sequentially cleaves the three C–Cl bonds of trichloromethyl groups is perceived to be a particularly attractive route (Figure b, right) because (i) many trichloromethyl (CCl 3 ) sources (i.e., CCl 3 CO 2 H manufactured industrially) are bulky chemicals and are also easy to insert; (ii) C­(sp 3 )–Cl bonds can engage in various types of C–C bond-forming reactions; − (iii) monochlorinated tertiary stereocenters resulting from two C­(sp 3 )–Cl functionalizations are valuable structural motifs that can be found in a large number of bioactive molecules , and can also serve as useful synthetic intermediates; − and (iv) this streamlined sequence not only obviates any preactivation steps but also allows for convenient and facile variations of each substituent. However, this promising strategy has not yet been reported, and a main hurdle is the comparable reactivity of C–Cl bonds in chemically similar tri- and dichloroalkyl groups that induces inferior control of chemoselectivity during the dechlorination process.…”

Ni/Photoredox-Catalyzed C(sp3)–C(sp3) Coupling between Aziridines and Acetals as Alcohol-Derived Alkyl Radical Precursors

“…5 Nevertheless, recently, there has been important progress made in this area using Ni 6 or Cu catalysis 7 with chemical reductants and electrochemical methods. 8 These approaches typically rely on substrate stoichiometry, differences in (pseudo)halide identities, or differences in substitution at the carbon center to achieve selectivity. Alternatively, redox-neutral metallaphotoredox catalysis 9 can provide a platform for the development of chemoselective C(sp 3 )−C(sp 3 ) cross-coupling in part by relying on orthogonal redox-dependent activation mechanisms of the two alkyl coupling partners.…”

Nickel-Catalyzed C(sp3)–C(sp3) Cross-Electrophile Coupling of In Situ Generated NHP Esters with Unactivated Alkyl Bromides

“…While cross-selectivity has proven challenging, radical-based cross-electrophile , approaches to C­(sp 3 )–C­(sp 3 ) bonds generally occur with little β-hydride elimination and allow for rapid construction of molecular complexity. To date, electrophiles have primarily included alkyl halides and aliphatic alcohol derivatives or amine-derived alkylpyridinium salts . Decarboxylative cross-coupling of unactivated alkyl carboxylic acids with unactivated alkyl bromides for the construction of C­(sp 3 )–C­(sp 3 ) bonds remains comparatively rare. − MacMillan and co-workers have reported two different multimetallic photoredox approaches in this area that are useful for 3°/1° and 2°/1° cross-coupling.…”