Synthesis of diazaadamantanes from 1,5-dimethylbispidinone and some natural ketones

1,5-Dimethylbispidinone (1,5-dimethyl-3,7-diazabicyclo[3.3.1]nonan-9-one) reacts with natural ketones, including optically active ones, to give new aminal-type compounds combining diazaadamantane and aliphatic fragments.