Haloselective Cross-Coupling via Ni/Photoredox Dual Catalysis.

ABSTRACT

The chemoselective functionalization of polyfunctional aryl linchpins is crucial for rapid diversification. Although well-explored for Csp2 and Csp nucleophiles, the chemoselective introduction of Csp3 groups remains notoriously difficult and is virtually undocumented using Ni catalysts. To fill this methodological gap, a "haloselective" cross-coupling process of arenes bearing two halogens, I and Br, using ammonium alkylbis(catecholato)silicates, has been developed. Utilizing Ni/photoredox dual catalysis, Csp3 -Csp2 bonds can be forged selectively at the iodine-bearing carbon of bromo(iodo)arenes. The described high-yielding, base-free strategy accommodates various protic functional groups. Selective electrophile activation enables installation of a second Csp3 center and can be done without the need for purification of the intermediate monoalkylated product.