title: Design of leaving groups in radical C-C fragmentations: through-bond 2c-3e interactions in self-terminating radical cascades.
abstract: Radical cascades terminated by β-scission of exocyclic CC bonds allow for the formation of aromatic products. Whereas β-scission is common for weaker bonds, achieving this reactivity for carbon-carbon bonds requires careful design of radical leaving groups. It has now been found that the energetic penalty for breaking a strong σ-bond can be compensated by the gain of aromaticity in the product and by the stabilizing two-center, three-electron "half-bond" present in the radical fragment. Furthermore, through-bond communication of a radical and a lone pair accelerates the fragmentation by selectively stabilizing the transition state. The stereoelectronic design of radical leaving groups leads to a new, convenient route to Sn-functionalized aromatics.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390 (USA).
authors.forename: Sayantan
authors.initials: S
authors.lastname: Mondal
authors.forename: Brian
authors.initials: B
authors.lastname: Gold
authors.forename: Rana K
authors.initials: RK
authors.lastname: Mohamed
authors.forename: Igor V
authors.initials: IV
authors.lastname: Alabugin
keywords: alkynes; cyclization; domino reactions; radical reactions; through-bond interactions