Accessing molecularly complex azaborines: palladium-catalyzed Suzuki-Miyaura cross-couplings of brominated 2,1-borazaronaphthalenes and potassium organotrifluoroborates.

Despite their potential applications in both medicinal chemistry and materials science, there have been limited reports on the functionalization of 2,1-borazaronaphthalenes since their discovery in 1959. To access new chemical space and build molecular complexity, the Suzuki-Miyaura cross-coupling of brominated 2,1-borazaronaphthalenes has been investigated. The palladium-catalyzed cross-coupling proceeds with an array of potassium (hetero)aryltrifluoroborates in high yield with low catalyst loadings under mild reaction conditions. By the use of a high-yielding bromination of various 2,1-borazaronaphthalenes to generate electrophilic azaborine species, a library of 3-(hetero)aryl and 3,6-diaryl-2,1-borazaronaphthalenes has been synthesized.