Double-Mannich Annulation of Cyclic Ketones Using <i>N</i>,<i>N</i>-Bis(ethoxymethyl)alkylamine Reagents

N,N-Bis(ethoxymethyl)alkylamines function as effective reagents in the double-Mannich annulation of cyclic ketone substrates, providing efficient access to a series of azabicyclic ketones. These ring systems are a useful scaffold for the four-step synthesis of novel constrained homocholine analogues.