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Photochemically Enabled, Ni-Catalyzed Cyanation of Aryl Halides

Yonggang Yan, Jinjin Sun, Gang Li, Liu Yang, Wei Zhang, Rui Cao, Chao Wang, Jianliang Xiao and Dong Xue*

*Key Laboratory of Applied Surface and Colloid Chemistry, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710119, China, Email: xuedong_welcomesnnu.edu.cn

Y. Yan, J. Sun, G. Li, L. Yang, W. Zhang, R. Cao, C. Wang, J. Xiao, D. Xue, Org. Lett., 2022, 24, 2271-2275.

DOI: 10.1021/acs.orglett.2c00203


Abstract

Visible light promotes a Ni-catalyzed cyanation of aryl halides with 1,4-dicyanobenzene as a cyanating agent. A broad array of aryl bromides, chlorides, and druglike molecules could be converted into their corresponding nitriles.

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proposed mechanism



Standard procedure for transfer cyanation of aryl bromides

To an oven-dried 10 mL glass storage tube with a stir bar were added NiI2 (5 mol%), dtbbpy (5 mol%), aryl bromide (0.4 mmol) and 1,4-DCB (0.8 mmol, 2.0 equiv). The mixture was evacuated and backfilled with Ar for 3 times, then DBU (0.8 mmol, 2.0 equiv), (TMS)3SiH (0.4 mmol, 1.0 equiv), toluene (4.0 mL) and TMSBr (0.4 mmol, 1.0 equiv) were added via a syringe, respectively. The reaction mixture was placed in an assembled photoreactor, stirred and irradiated with 9 W purple LEDs (390-395 nm, approximately 1 cm away from the tube, optical power: 200 10 mw/cm2) for 16 hours. The average temperature of reaction mixture was 50C without extra heating. After cooling to room temperature, the reaction mixture was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain aryl nitriles.

Standard procedure for transfer cyanation of aryl chlorides

To an oven-dried 10 mL glass storage tube with a stir bar were added NiI2 (10 mol%) dtbbpy (10 mol%), aryl chloride (0.4 mmol) and 1,4-DCB (0.8 mmol, 2.0 equiv). The mixture was evacuated and backfilled with Ar for 3 times, then DBU (0.8 mmol, 2.0 equiv), (TMS)3SiH (0.4 mmol, 1.0 equiv), PhOMe (4.0 mL) and TMSBr (0.8 mmol, 2.0 equiv) were added via a syringe, respectively. The reaction mixture was placed in an assembled photoreactor, stirred and irradiated with 9 W purple LEDs (390-395 nm, approximately 1 cm away from the tube, optical power: 200 10 mw/cm2) for 36 hours. The average temperature of reaction mixture was 50C without extra heating. After cooling to room temperature, the reaction mixture was concentrated under vacuum. The crude product was purified by silica gel column chromatography to obtain aryl nitriles.


Key Words

cyanation, TTMSS, photochemistry


ID: J54-Y2022