C(sp2)-C(sp2) and C(sp2)-C(sp3) Nickel-Catalyzed Kumada-Corriu and Buchwald-Hartwig Cross-Coupling of Aryl Sulfamates Enabled by Sterically-Demanding, Electron-Rich IPr*OMe N-Heterocyclic Carbenes.

Abstract

Nickel-catalyzed cross-coupling reactions are among the most powerful tools in organic synthesis owing to the low cost, natural abundance and high activity of versatile nickel catalysts. However, there is a scarcity of efficient Ni-catalyzed systems for the cross-coupling of bench-stable, readily accessible and orthogonal C-O electrophiles. Herein, we report the cross-coupling of aryl sulfamates enabled by sterically-demanding and electron-rich N-heterocyclic carbenes. The study identified sulfamates as the most reactive C-O electrophiles enabled by a combination of IPr*^OMe bearing sterically-demanding ortho-diphenyl wingtip substitution and NiF₂ exploiting the fluoride effect. The system enables efficient C(sp²)-C(sp²) and C(sp²)-C(sp³) cross-coupling avoiding hydrolysis, homocoupling and unselective C-O and S-N cleavages, providing a powerful platform for the orthogonal use of C-O electrophiles. The system is also applicable to Buchwald-Hartwig amination. The broad access to electron-rich, sterically-demanding N-heterocyclic carbenes combined with the high reactivity of aryl sulfamates furnishes a commanding avenue for the development of Ni-catalyzed processes in academic and industrial research.