Chemo- and Regioselectivity in Allenamide-Homoenolate Coupling

We report herein a chelation assisted, ring-strain-driven homoenolate interception with allenamides, proceeding through a complementary reactivity pattern─noncycloaddition and central C interception of C-pronucleophiles─distinct from previous studies. The developed atom-economical method provides access to carbonyl-tagged enamides with high chemo- and regioselectivity, offering a broad scope and significant synthetic value, as demonstrated by further diversification. The origin of the selectivity is clarified through experimental mechanistic investigations, revealing the detailed reaction pathway proceeding through a carbopalladation event.