Thermal Elimination of Diethyldithiocarbamates and Application in the Synthesis of (±)-Ferrugine

Dithiocarbamate-substituted lactams, prepared through group-transfer cyclization reactions of carbamoyl radicals, undergo a Chugaev-like thermal elimination of the dithiocarbamate group in refluxing diphenyl ether to form α,β- and/or β,γ-unsaturated amides, depending on the structure of the starting material. This reaction sequence was used to prepare an unsaturated [3.2.2] bridged bicyclic amide, which was converted in a one-pot procedure to the 8-azabicyclo[3.2.1]octane ring system of the tropane alkaloid ferrugine by treatment with phenyllithium followed by aqueous sodium hydroxide.