Mechanistic insights for the photoredox organocatalytic fluorination of aliphatic carbons by anthraquinone using time-resolved and DFT studies
Kee, J. W.
Kee, C. W.
Soo, Han Sen
Tan, Choon Hong
Date of Issue2017
School of Physical and Mathematical Sciences
Chemoselective photoredox fluorination is an appealing approach to access fluorinated fine chemicals such as active pharmaceutical ingredients, but most of the known procedures currently lack time-resolved mechanistic insights. We use nanosecond transient absorption spectroscopy and density functional theory (DFT) calculations to elucidate the elementary steps after irradiation in a photocatalytic fluorination procedure that we reported previously. Time-resolved optical spectroscopy suggests that direct reaction only occurs between the photoexcited anthraquinone (AQN) and Selectfluor®. We have observed spectroscopic evidence of a novel transient AQN–Selectfluor® species for the first time. Further studies by DFT calculations suggest that the AQN–Selectfluor® triplet exciplex formed by photoirradiation is responsible for initiating and sustaining the fluorination reaction.
Catalysis Science & Technology
© 2017 Royal Society of Chemistry. This is the author created version of a work that has been peer reviewed and accepted for publication by Catalysis Science & Technology, Royal Society of Chemistry. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1039/C6CY02484J].