Late-Stage Functionalization of 1,2-Dihydro-1,2-azaborines via Regioselective Iridium-Catalyzed C–H Borylation: The Development of a New N,N-Bidentate Ligand Scaffold

• Published in: Journal of the American Chemical Society Vol. 137; no. 16; pp. 5536 - 5541
• Main Authors: Baggett, Andrew W, Vasiliu, Monica, Li, Bo, Dixon, David A, Liu, Shih-Yuan
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 29.04.2015; Amer Chemical Soc
• Subjects: absorption; boron; bromides; Chemistry; Chemistry, Multidisciplinary; hydrides; ligands; photoluminescence; Physical Sciences; Science & Technology; ACTIVATION; B-N; COMPLEXES; CONSTRUCTION; ARYLATION; 1,2-AZABORINES; BIPYRIDINE; AROMATIC-SUBSTITUTION REACTIONS; INSIGHTS; DIBORON
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.5b01916

The first general late-stage functionalization of monocyclic 1,2-azaborines at the C(6) position is described. Ir-catalyzed C–H borylation occurs regioselectively at the C(6) position of B-substituted 1,2-azaborines and is compatible with a range of substitution patterns at boron (e.g., hydride, alkoxide, alkyl, and aryl substituents). Subsequent Suzuki cross coupling with aryl- and heteroaryl bromides furnishes 1,2-azaborine-based biaryl compounds including 6-[pyrid-2-yl]-1,2-azaborines that represent novel κ2-N,N-bidentate ligands. The 6-[pyrid-2-yl]-B-Me-1,2-azaborine ligand has been demonstrated to form an emissive coordination complex with dimesitylboron that exhibits bathochromically shifted absorption and emission maxima and a higher photoluminescence quantum yield compared to its carbonaceous analogue.