Entangled dual-site migration via boracycle rearrangement

Migration is a fundamental chemical transformation. Beyond scientific curiosity and mechanistic intrigue, migration reactions offer ingenious approaches to remote or otherwise challenging reaction sites, complementary to traditional synthetic methodologies.1 While single-site migration has been extensively studied with great regioselectivity control, orchestrating the concurrent migration of two distant sites along a carbon chain remains largely unexplored.2,3 This is primarily due to the exponentially raised complexity in controlling chemo-, regio-, and diastereoselectivity at two migrating centers. Here, we present a proof-of-concept strategy of entangled dual-site migration, enabled by a process we term the “borinane rearrangement”—a lead-and-follow movement of a borinane ring along the carbon backbone. This boracycle rearrangement traverses up to eight carbon atoms, allowing for precise control over both regio- and diastereoselectivity at two migrating positions. Moreover, the boracyclic products serve as versatile synthons for divergent synthesis of (hetero)cycles and epsilon-difunctionalization (one introduced functional group is four carbons away from the other), significantly expanding the chemical space of (hetero)cycle construction and multi-site modification, especially at the central regions of carbon chains.