Amide‐Enabled Reversal of Regioselectivity in Carbonyl‐Substituted Allenes

Overriding β‐selective nucleophilic addition to carbonyl‐conjugated π‐systems is a persistent challenge in regioselective synthesis. Here we report that a secondary amide embedded in carbonyl‐substituted allenes enables highly α‐selective acyloxylation with carboxylic acids under rhodium catalysis. The reaction proceeds without external oxidants or auxiliary‐type bidentate directing groups and tolerates a wide range of aromatic, heteroaromatic, aliphatic, and alkenyl carboxylic acids. Control experiments with ketone, ester, and N ‐methyl amide analogs reveal that the secondary amide functionality is essential for productive α‐selective coupling. These results indicate a substrate‐embedded secondary amide strategy for redirecting nucleophilic addition to carbonyl‐substituted allenes.