38. 1,3-Alkyl Transposition in Allylic Alcohols Enabled by Proton-Coupled Electron Transfer

Kuo Zhao, Gesa Seidler, Robert R. Knowles

Angew. Chem. Int. Ed. 2021, 60, 20190–20195. DOI: 10.1021/ja404342j

https://onlinelibrary.wiley.com/doi/10.1002/anie.202105285

ABSTRACT: A method is described for the isomerization of acyclic allylic alcohols into β-functionalized ketones via 1,3-alkyl transposition. This reaction proceeds via light-driven proton-coupled electron transfer (PCET) activation of the O–H bond in the allylic alcohol substrate, followed by C–C β-scission of the resulting alkoxy radical. The transient alkyl radical and enone acceptor generated in the scission event subsequently recombine via radical conjugate addition to deliver β-functionalized ketone products. A variety of allylic alcohol substrates bearing alkyl and acyl migratory groups were successfully accommodated. Insights from mechanistic studies led to a modified reaction protocol that improves reaction performance for challenging substrates.