Acyl-oxyallenes as α,β-unsaturated ketone surrogates for Giese radical addition

Abstract

Oxyallenes are valuable building blocks in organic synthesis, most commonly exploited as π-allyl metal precursors in transition-metal-catalyzed allylation reactions. In contrast, their engagement in radical processes remains largely unexplored. Herein, we disclose a Giese-type radical addition protocol in which acyl-substituted oxyallenes function as in situ precursors to α,β-unsaturated ketones, enabling efficient coupling with 2-azaallyl radicals. This metal-free method delivers a wide range of γ-amino ketones in high yields with broad functional group tolerance, mild conditions, and scalability to gram quantities. Mechanistic studies, including radical trapping and isotopic labeling, support a pathway involving radical addition of the 2-azaallyl radical to transient enone intermediates. These findings establish a new reactivity mode of oxyallenes in radical chemistry and provide an efficient route to synthetically and pharmaceutically valuable amino ketones.