Mechanochemical Iridium(III)-Catalyzed B-Amidation of o-Carboranes with Dioxazolones

Abstract

Mechanochemistry was successfully applied to the functionalization of carboranes. The mechanochemical iridium­(III)-catalyzed regioselective B(3)- and B(4)-amidation of unsubstituted o-carboranes with dioxazolones was developed. In addition, the mechanochemical iridium­(III)-catalyzed regioselective B(4)-amidation of substituted o-carboranes was demonstrated. Because mechanochemical B-amidation proceeds smoothly without organic solvents or external heating, the present method is regarded as a sustainable and environmentally friendly surrogate for typical solvent-based reactions.

Mechanochemical Direct Fluorination of Unactivated C(sp3)−H Bonds

“…They feature solvent‐free or solventless conditions (which allow close contact between reactants), reduced reaction times, and simple operation. In addition to their environmental sustainability, mechanochemical reactions occasionally exhibit distinctive reactivity and selectivity that are completely different from those of typical organic synthesis reactions in solution [1b,f–l] …”

Palladium-Catalyzed Regioselective B(9)-Amination of o-Carboranes and m-Carboranes in HFIP with Broad Nitrogen Sources

“…A considerable progress in the amination of o -carboranes and their derivatives has been made only in the recent few years. With carboxylic acid as the directing group, a series of B(4)-amination works have been reported with different nitrogen sources, including O -benzoyl hydroxyl dialkyl amines, sulfonyl azides, , and dioxazolones (Scheme a). Recently, Xie and co-workers reported an elegant selective B(3)-H amination of o -carboranes with NH 3 gas as the nitrogen source via Ir-catalyzed B(3)-H activation (Scheme b) .…”

Highly selective electrophilic B(9)-amination of o-carborane driven by HOTf and HFIP

“…14 However, compared with their great importance, only limited examples of their synthesis have been reported 15 and in most cases relied on the transition-metal-catalyzed B–H bond activation. 11 d ,16 With halogenated carboranes as substrates, the Pd( ii )-catalyzed Buchwald–Hartwig amination of carboranes provides another efficient way for the construction of the B–N bond. 17 Very recently, we achieved the regioselective B(9)-amination of o -carboranes and m -carboranes in HFIP with a wide range of nitrogen sources through Pd( ii )-catalyzed B–H activation (Scheme 1a).…”