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Published on: October 5, 2019
Photosensitizer-Free Benzo[1,4]oxazin-2-one Synthesis by Continuous-Flow Photochemistry
Eunhui Park1, Shrikant D Tambe1, Jongbok Lee2
1Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea.
Abstract:
We report a photosynthetic method for producing 2H-benzo[b][1,4]oxazin-2-ones from aryl azides and α-ketoacids. This method is highly sustainable, requiring only visible light irradiation of the substrates and no external additives. Furthermore, we implemented a continuous-flow system to achieve efficient light irradiation and rapid mixing, significantly improving reaction efficiency and reducing reaction time compared to the batch process. The flow system enabled gram-scale synthesis. We also demonstrated the utility of the products, by employing the benzo[1,4]oxazin-2-one moiety as a directing group for C-H activation on the 3-aryl substituent. This green approach highlights the potential for developing environmentally friendly synthetic processes.
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