Balancing Reactivity, Regioselectivity, and Product Stability in Ir-Catalyzed Ortho-C-H Borylations of Anilines by Modulating the Diboron Partner.

Ir-catalyzed arene C-H borylations (CHB) of anilines can be highly ortho selective by using a small B 2 eg 2 (eg = ethane-1,2-diol) as the borylating reagent. Unfortunately, the products are prone to decomposition, and transesterification with pinacol is required prior to isolation. This work offers a solution by adjusting the size of the diboron reagent. Based on our evaluation, we conclude that B 2 bg 2 (bg = butane-1,2-diol) achieves an optimal balance between CHB regioselectivity and stability for the borylated products.