Azahelicenes from the Oxidative Photocyclization of Boron Hydroxamate Complexes

作者：Murase Takashi^*; Suto Toru; Suzuki Honoka

来源：Chemistry-An Asian Journal, 2017, 12(7): 726-729.

DOI：10.1002/asia.201700096

• continuous flow
• helical structures
• helicenes
• hydroxamic acids
• photocyclization

Aromatic hydroxamic acids (Ar-CO-NOH-Ar ') were used as bidentate chelating ligands to generate the corresponding boron hydroxamate complexes, which were subsequently transformed into nitrogen-containing helicenes (azahelicenes) using an oxidative photocyclization method that is frequently used for stilbene-type (ArCH=CH-Ar ') precursors of carbohelicenes. The nitrogen atom of the hydroxamate linker was thus directly embedded into the helicene core without using nitrogen-containing aromatic rings in the stilbene-type precursors. In a batch photoreaction, aza[4] helicenes were readily and efficiently prepared, but aza[6] helicenes underwent severe decomposition upon irradiation. Alternatively, a continuous flow photoreactor was employed to furnish an amide-type aza[6]helicene.

• 出版日期2017-4-4