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

Titelangaben

Jana, Sripati ; Yang, Zhen ; Li, Fang ; Empel, Claire ; Ho, Junming ; Koenigs, Rene M.:
Photoinduced Proton‐Transfer Reactions for Mild O‐H Functionalization of Unreactive Alcohols.
In: Angewandte Chemie International Edition. Bd. 59 (2020) . - S. 5562-5566.
ISSN 1521-3773
DOI: https://doi.org/10.1002/anie.201915161

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Abstract

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. Mechanistic studies indicate there is a preorganization of hexafluoroisopropanol and the diazoalkane acts as an unreactive hydrogen-bonding complex. Only after photoexcitation does this complex undergo a protonation-substitution reaction to the reaction product. Investigations on the applicability of this photochemical transformation show that a broad variety of acidic alcohols can be subjected to this transformation and thus demonstrate the feasibility of this concept for O-H functionalization reactions (54 examples, up to 98 % yield).