Accessing Molecularly Complex Azaborines: Palladium-Catalyzed Suzuki–Miyaura Cross-Couplings of Brominated 2,1-Borazaronaphthalenes and Potassium Organotrifluoroborates

Abstract

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.

Denitrogenative Pd/Cu‐catalyzed Suzuki‐type Cross‐coupling of Aryltrifluoroborates with Arylhydrazine Hydrochlorides in Water under Room Temperature

“…Traditionally, aryl halides are most widely used electrophilic reagents in Pd‐catalyzed Suzuki‐type cross‐coupling reactions with organotrifluoroborates (Scheme , C–X bond) . Subsequently, the methods utilizing aryl ester which derived from the respective phenols in Suzuki‐type coupling with organotrifluoroborates have been developed.…”

Accessing 2,1-Borazaronaphthols: Self-Arylation of 1-Alkyl-2-aryl-3-bromo-2,1-borazaronaphthalenes

“…2 These studies demonstrated the stability of these azaborines 3 to transition metal catalysis and allowed access to functionalized molecules that could have applications in medicinal chemistry 4 and/or materials science. 5 During the course of this latter study, we first developed conditions for the cross-coupling of N -H and N -alkyl 3-bromo- B - alkyl -2,1-borazaronaphthalenes (eq 1).…”

Pd‐catalyzed Desulfitative reaction of Aryltrifluoroborates with sodium Arenesulfinates in water

“…Traditionally, aryl halides are most widely used electrophilic reagents in Pd-catalyzed Suzuki cross-coupling reactions with organotrifluoroborates (Scheme 1, C-X cleavage). [16][17][18][19][20][21][22][23] Subsequently, the methods utilizing aryl tosylates which derived from the respective phenols in Suzuki coupling with organotrifluoroborates have been developed. The transformation proceeded via C-O bond cleavage instead of C-X bond (Scheme 1, C-O cleavage).…”