Entangled dual-site migration through boracycle rearrangement.

Migration is a fundamental chemical transformation. Beyond scientific curiosity and mechanistic intrigue, migration reactions offer approaches to remote or otherwise challenging reaction sites, complementary to traditional synthetic methodologies1. 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 unexplored2,3. This is primarily due to the exponentially raised complexity in controlling chemoselectivity, regioselectivity and diastereoselectivity at two migrating centres. Here we present a proof-of-concept strategy of entangled dual-site migration, enabled by a process that 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 regioselectivity 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), substantially expanding the chemical space of (hetero)cycle construction and multi-site modification, especially at the central regions of carbon chains.