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Enantioselective Visible‐Light‐Mediated Formation of 3‐Cyclopropylquinolones by Triplet‐Sensitized Deracemization
Author(s) -
Tröster Andreas,
Bauer Andreas,
Jandl Christian,
Bach Thorsten
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201814193
Subject(s) - photostationary state , enantioselective synthesis , chemistry , photochemistry , yield (engineering) , enantiomer , visible spectrum , enantiomeric excess , stereochemistry , organic chemistry , catalysis , materials science , photoisomerization , optoelectronics , isomerization , metallurgy
3‐Allyl‐substituted quinolones undergo a triplet‐sensitized di‐π‐methane rearrangement reaction to the corresponding 3‐cyclopropylquinolones upon irradiation with visible light ( λ =420 nm). A chiral hydrogen‐bonding sensitizer (10 mol %) was shown to promote the reaction enantioselectively (88–96 % yield, 32–55 % ee ). Surprisingly, it was found that the enantiodifferentiation does not occur at the state of initial product formation but that it is the result of a deracemization event. The individual parameters that control the distribution of enantiomers in the photostationary state have been identified.