Access to Branched 1,3-Dienes via Innate C(sp³)–H Functionalization of 8-Methylquinolines

Allenes have gained prominence in transition metal-catalyzed C-H activation reactions due to their versatile reactivity. While C(sp2)-H functionalization with allenes has been well explored, the functionalization of more challenging C(sp3)-H bonds with allenes remains largely underexplored. Herein, we present a scalable Rh(III)-catalyzed strategy for the site-selective C(sp3)-H dienylation of biologically relevant 8-methylquinolines employing allenyl carbinol acetates for accessing structurally diverse 1,3-dienes. Leveraging the innate directing group ability of the quinoline nitrogen, our protocol promotes the selective 2,1-migratory insertion of allenes. The transformation exhibits a broad substrate scope and enables the late-stage construction of densely functionalized 1,3-diene conjugates with biologically relevant motifs, highlighting the synthetic utility and broad applicability of this method.