Access to novel substituted diazaadamantanes via semi-natural tetrahydrocytisine

Novel 1,3-diazaadamantane structures 3 and 6 were prepared from tetrahydro(−)-cytisine 1 using intermolecular conversions within the bispidine moiety. 2-Oxo derivative 6 was synthesized using a microwave-assisted procedure, which reduces the reaction time and increases the purity of the crude reaction mixture. Alternative possibilities of intermolecular cyclizations were also explored. Though less successful, they provided interesting insights into the chemistry of bispidine systems.