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- Title
Asymmetric Photocatalysis by Intramolecular Hydrogen‐Atom Transfer in Photoexcited Catalyst–Substrate Complex.
- Authors
Zhang, Chenhao; Chen, Shuming; Ye, Chen‐Xi; Harms, Klaus; Zhang, Lilu; Houk, K. N.; Meggers, Eric
- Abstract
3‐(2‐Formylphenyl)‐1‐pyrazol‐1‐yl‐propenones undergo an asymmetric photorearrangement to benzo[d]cyclopropa[b]pyranones with up to >99 % ee, which is catalyzed by a bis‐cyclometalated rhodium catalyst in the presence of visible light. Mechanistic experiments and DFT calculations support a mechanism in which a photoexcited catalyst/substrate complex triggers an intramolecular hydrogen‐atom transfer followed by a highly stereocontrolled hetero‐Diels–Alder reaction. In this reaction scheme, the rhodium catalyst fulfills multiple functions by 1) enabling visible‐light π→π* excitation of the catalyst‐bound enone substrate, 2) facilitating the hydrogen‐atom transfer, and 3) providing the asymmetric induction for the hetero‐Diels–Alder reaction.
- Subjects
ASYMMETRIC synthesis; RHODIUM catalysts; PHOTOCATALYSIS; VISIBLE spectra; SIGMATROPIC rearrangements
- Publication
Angewandte Chemie, 2019, Vol 131, Issue 41, p14604
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.201905647