Orchestrating Multiple Aryl Rearrangements: Deciphering the Dynamics of Competitive Shifts and Shuttles on Four Carbons

Multiple aryl rearrangement and translocation reactions on aromatic scaffolds remain scarce and represent a compelling frontier in organic synthesis. Herein, we portray a comprehensive investigation of multiple sequential 1,2-naphthyl shift and aryl shuttle reactions on heteroaromatic scaffolds, including an unprecedented aryl shuttle on a bicyclic arene. For the first time, we delineate the competition between the dynamic 1,2-aryl shift and aryl shuttle events on a heteroarene, uncovering their sequential progression and revealing how aryl electronics and positional effects dictate equilibrium composition. Detailed mechanistic studies unambiguously establish that aryl shuttle reactions proceed via a stepwise pathway, ruling out simultaneous migration or [c]-face shuttling. By strategically orchestrating these rearrangements, we achieve up to 16 sequential aryl migrations across the four carbons of a thiophene core, showcasing an unprecedented level of precision and control. By integration of aryl shifts with shuttle events, this work pioneers a new paradigm for engineering multiple molecular rearrangements on aromatic systems. Beyond deepening our fundamental understanding of acid-mediated transformations, this study paves the way for programmable molecular choreography, opening exciting avenues in organic synthesis and materials design.