Chiral Iron Porphyrins Catalyze Enantioselective Intramolecular C(sp3)−H Bond Amination Upon Visible‐Light Irradiation

• Published in: Angewandte Chemie International Edition Vol. 62; no. 19; pp. e202218577 - n/a
• Main Authors: Wang, Hua‐Hua, Shao, Hui, Huang, Guanglong, Fan, Jianqiang, To, Wai‐Pong, Dang, Li, Liu, Yungen, Che, Chi‐Ming
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 02.05.2023; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Amination; Asymmetric Catalysis; Asymmetry; Biocompatibility; Chemistry; Chemistry, Multidisciplinary; Enantiomers; Heterocyclic compounds; Hydrogen atoms; Hydrogen bonds; Iron; Irradiation; Light irradiation; Photocatalysis; Photochemicals; Photochemistry; Physical Sciences; Porphyrins; Radiation; Science & Technology; Sulfonamides; ORGANIC-SYNTHESIS; Asymmetric Catalysis; AZIDES; Amination; Photocatalysis; AZIRIDINATION; AMIDATION; RUTHENIUM; Iron; METAL; C-H AMINATION; Porphyrins
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202218577

Iron‐catalyzed asymmetric amination of C(sp3)−H bonds is appealing for synthetic applications due to the biocompatibility and high earth abundance of iron, but examples of such reactions are sparse. Herein we describe chiral iron complexes of meso‐ and β‐substituted‐porphyrins that can catalyze asymmetric intramolecular C(sp3)−H amination of aryl and arylsulfonyl azides to afford chiral indolines (29 examples) and benzofused cyclic sulfonamides (17 examples), respectively, with up to 93 % ee (yield: up to 99 %) using 410 nm light under mild conditions. Mechanistic studies, including DFT calculations, for the reactions of arylsulfonyl azides reveal that the Fe(NSO2Ar) intermediate generated in situ under photochemical conditions reacts with the C(sp3)−H bond through a stepwise hydrogen atom transfer/radical rebound mechanism, with enantioselectivity arising from cooperative noncovalent interactions between the Fe(NSO2Ar) unit and the peripheral substituents of the chiral porphyrin scaffold. An efficient method has been developed for the chiral iron porphyrin catalyzed transformation of aryl and arylsulfonyl azides into chiral indolines and sultams, respectively. The reaction proceeds upon visible light irradiation and with high yields and excellent enantioselectivities.