Regio‐ and Enantioselective Photodimerization within the Confined Space of a Homochiral Ruthenium/Palladium Heterometallic Coordination Cage

• Published in: Angewandte Chemie International Edition Vol. 56; no. 14; pp. 3852 - 3856
• Main Authors: Guo, Jing, Xu, Yao‐Wei, Li, Kang, Xiao, Li‐Min, Chen, Sha, Wu, Kai, Chen, Xu‐Dong, Fan, Yan‐Zhong, Liu, Jun‐Min, Su, Cheng‐Yong
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 27.03.2017; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Anaerobic conditions; Cages; Chemistry; Chemistry, Multidisciplinary; Confined spaces; Coordination; coordination cages; Coupling; couplings; Dimerization; Enantiomers; homochiral cages; Intermediates; Palladium; photoreactions; Physical Sciences; Ruthenium; Science & Technology; Stereoselectivity; OXIDATION; couplings; KNOEVENAGEL; stereoselectivity; coordination cages; CAVITY; METAL-ORGANIC CAGES; GUEST; photoreactions; DUAL-CATALYSIS; homochiral cages; PHOTOREDOX CATALYSIS
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201611875

The photoinduced regio‐ and enantioselective coupling of naphthols and derivatives thereof is achieved in the confined chiral coordination space of a RuII metalloligand based cage. The racemic or enantiopure cages encapsulate naphthol guests, which then undergo a regiospecific 1,4‐coupling, rather than the normal 1,1‐coupling, to form 4‐(2‐hydroxy‐1‐naphthyl)‐1,2‐napthoquinones; moderate stereochemical control is achieved with homochiral cages. The photoreactions proceed under both aerobic and anaerobic conditions but through distinct pathways that nevertheless involve the same radical intermediates. This unusual dimerization constitutes a very rare example of asymmetric induction in biaryl coupling by making use of coordination cages with dual functionality—photoredox reactivity and stereoselectivity. Confined coordination spaces in redox‐active ruthenium(II) cages enable the photoinduced regio‐ and enantioselective coupling of naphthol and derivatives thereof. The photoreactions proceed under both aerobic and anaerobic conditions but by distinct pathways that nevertheless involve the same radical intermediates.