Seminar Abstract:

Amines are among the most prevalent functional group encountered in biologically active molecules and synthetic chemistry. Traditionally treated as synthetic end points, amines have recently emerged as valuable alkyl radical precursors. Central to these transformations is activation of the nitrogen center to reduce the Csp3–N bond dissociation energy. One activation strategy involves the in situ formation of amine-borane adducts. These complexes undergo facile hydrogen atom abstraction at the boron center and subsequent β-scission across the C–N bond, forming a nucleophilic alkyl radical. However, the capacity of these amine-boranes to undergo conventionally difficult C–N β-scission remains largely unexplored. Employing cyclic amines under this regime would provide access to ring-opened alkyl radical species. Subsequent reduction and reaction with diiodomethane would afford a one-carbon ring-expansion of saturated nitrogen heterocycles. This transformation would deliver homologated analogs of structurally complex cyclic amines in a single step. Additionally, a direct and general method for deaminative fluorination could be realized by employing N-fluorosulfonamides as a modular fluorine source with amine-boranes via copper-catalysis.