Sustainable access to B,B′,B″-tri(aryl)borazines via a triflic anhydride-promoted/microwave approach

Abstract

The doping of an organic backbone with boron and nitrogen has recently garnered significant attention in the scientific community. In this context, the incorporation of borazine moieties into molecular scaffolds has imparted unique (opto)electronic properties that differ substantially from those of their all-carbon analogs. Despite their promising characteristics and potential applications in materials science, their broader use is hampered by synthetic challenges. Specifically, the synthesis of borazine-containing compounds often necessitates strictly controlled anhydrous conditions, prolonged reaction times, and the use of hazardous starting materials and solvents. To address these limitations, we have developed an efficient and more environmentally friendly catalytic protocol for the synthesis of B,B′,B″-tri(aryl)borazines, avoiding the use of both metals and solvents. By exploiting microwave-assisted heating, we optimized the reaction conditions, significantly reducing reaction times while using triflic anhydride as a sub-stoichiometric promoter and minimizing the amount of hexamethyldisilazane (HMDS) without compromising yield or product integrity. The optimized reaction conditions, to the best of our knowledge, enabled the efficient synthesis of a diverse array of substrates for the first time, providing a promising foundation for further investigation into their potential applications in advanced materials development.