title: Electron-transfer photoredox catalysis: development of a tin-free reductive dehalogenation reaction.
abstract: We report an operationally simple, tin-free reductive dehalogenation system utilizing the well-known visible-light-activated photoredox catalyst Ru(bpy)(3)Cl(2) in combination with (i)Pr(2)NEt and HCO(2)H or Hantzsch ester as the hydrogen atom donor. Activated C-X bonds may be reduced in good yields with excellent functional-group tolerance and chemoselectivity over aryl and vinyl C-X bonds. The proposed mechanism involves visible-light excitation of the catalyst, which is reduced by the tertiary amine to produce the single-electron reducing agent Ru(bpy)(3)(+). A subsequent single-electron transfer generates the alkyl radical, which is quenched by abstraction of a hydrogen atom. Reductions can be accomplished on a preparative scale with as little as 0.05 mol % Ru catalyst.
authors: Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA.
authors: Jagan M R
authors: JM
authors: Narayanam
authors: Joseph W
authors: JW
authors: Tucker
authors: Corey R J
authors: CR
authors: Stephenson