Transition metal-free visible light photoredox-catalyzed remote C(sp3)−H borylation enabled by 1,5-hydrogen atom transfer

• Published in: Communications chemistry 2023-07, Vol.6 (1), p.156-156, Article 156
• Main Authors: Sun, Beiqi, Li, Wenke, Liu, Qianyi, Zhang, Gaoge, Mo, Fanyang
• Format: Article
• Language: English
• Subjects: 639/638/403/933; 639/638/439/890; 639/638/77/888; Carbon; Carbonyl compounds; Carbonyls; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Esters; Functional groups; Hydrogen; Hydrogen atoms; Hydrogen bonds; Light; Nitrogen; Photocatalysis; Photoredox catalysis; Radicals; Substrates; Transition metals
• ISSN: 2399-3669; 2399-3669
• DOI: 10.1038/s42004-023-00960-z

The borylation of unreactive carbon-hydrogen bonds is a valuable method for transforming feedstock chemicals into versatile building blocks. Here, we describe a transition metal-free method for the photoredox-catalyzed borylation of unactivated C(sp 3 )−H bond, initiated by 1,5-hydrogen atom transfer (HAT). The remote borylation was directed by 1,5-HAT of the amidyl radical, which was generated by photocatalytic reduction of hydroxamic acid derivatives. The method accommodates substrates with primary, secondary and tertiary C(sp 3 )−H bonds, yielding moderate to good product yields (up to 92%) with tolerance for various functional groups. Mechanistic studies, including radical clock experiments and DFT calculations, provided detailed insight into the 1,5-HAT borylation process. Alkyl boronic esters are commonly used building blocks in organic synthesis, causing efficient C-H borylation methods to be in high demand. Here, the authors develop a method for the photoredox-catalyzed borylation of unreactive C(sp 3 )-H bonds, mediated by amidyl radicals to achieve C-H borylation at the λ position of carbonyl compounds.