Photochemistry is of considerable interest to the scientific community due to its ability to provide more environmentally friendly reaction conditions in organic synthesis. Recent studies from the Koenigs group identified a blue light-induced O-H functionalization of alcohols through reaction with aryldiazoacetates. The originally proposed mechanism for this reaction suggested that it occurs via excited state proton transfer with aryldiazoacetate acting as a photobase. Subsequent experiments by Huo and coworkers demonstrated a similar reaction between aryldiazoacetates and 2-pyridones. Here, we present our analysis of the reaction mechanism using density function theory calculations performed at the ωB97M-(2)/def2-QZVPP//ωB97X-D/def2-SVPD level of theory. Our results demonstrate that the reaction proceeds via a carbene intermediate produced through the photolysis of the aryldiazoacetate, indicating that the mechanism involves carbene chemistry and not photobasicity. We additionally provide mechanistic insights into the regioselectivity of the light-driven reaction between 2-pyridone and aryldiazoacetate.

Determining the photochemical mechanism of the O-H functionalization of phenols and 2-pyridones with aryldiazoacetate

ACS Spring 2022

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