Rearrangements of norbornenyl radicals: further evidence as to the mechanism of borohydride reduction of organomercurials
Abstract
Reductions of 3-acetoxy-5-norbornen-2-yl mercuric chloride, 5-acetoxy-3-nortricyclyl mercuric chloride, and 7-anti-acetoxy-2-exo-bromonorborn-5-ene with tributyltin hydride, triphenyltin hydride, or photochemically in methanol give similar isomeric mixtures of 2-exo-acetoxynorbornene, 7-anti-acetoxynorbornene, and 3-acetoxynortricyclene, as does reduction of the mercurials with sodium borohydride in aqueous tetrahydrofuran, indicating that a radical mechanism operates in the latter reaction.