The combination of 4,4,6-trimethyl-1,3,2-dioxaborinane, a particularly stable and inexpensive borylation reagent, and Buchwald's palladium catalyst provides a simple, fast, cost-effective borylation of electron-rich, reactive iodides, bromides, and triflates to produce stable, easily purified boronic esters.
The nickel-catalyzed borylation of aryl iodides and bromides with 4,4,6-trimethyl-1,3,2-dioxaborinane was achieved. The mild reaction conditions employed allowed for the inclusion of common functional groups in aryl halides to be tolerated. A DFT study on the catalytic cycle shows that C-B bond formation occurs through sigma-bond metathesis between dialkoxyborane and arylnickel(II) halide intermediates.