C(aryl)-O activation of aryl carboxylates in nickel-catalyzed biaryl syntheses.

Crucial breakthroughs in the activation of the C(aryl)-O bond of phenol derivatives were achieved almost simultaneously by two research groups (see scheme; Cy = cyclohexyl). Garg et al. coupled a range of aryl pivalates with arylboronic acids to give unsymmetrical biaryls. Shi et al. achieved this through C(aryl)-O activation of aryl carboxylates; the best results for the coupling of aryl boroxines were again obtained with aryl pivalates.