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Photoinduced Proton Transfer Reactions for Mild O-H Functionalization Reactions of Unreactive Alcohols

preprint
submitted on 18.11.2019 and posted on 27.11.2019 by Sripati Jana, Zhen Yang, Fang Li, Claire Empel, Junming Ho, Rene Koenigs
Hexafluoroisopropanol is typically considered as an unreactive solvent and not as a reagent in organic synthesis. Herein, we report on a mild and efficient photochemical reaction of aryl diazoacetates with hexafluoroisopropanol that enables, under stoichiometric reaction conditions, the synthesis of fluorinated ethers in excellent yield. We support these findings with mechanistic studies, which indicate a preorganization of hexafluoroisopropanol and the diazoalkane as an unreactive Lewis Acid-Base adduct. Only upon photoexcitation, this adduct undergoes a protonation-substitution reaction to the reaction product. We conclude with investigations on the applicability of this photochemical transformation and could show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept in O-H functionalization reactions (52 examples, up to 98% yield).

History

Email Address of Submitting Author

rene.koenigs@rwth-aachen.de

Institution

RWTH Aachen University

Country

Germany

ORCID For Submitting Author

0000-0003-0247-4384

Declaration of Conflict of Interest

No conflict to declare

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