Synthesis of isoquinuclidinones via a tandem amination/imination sequence: application to the synthesis of (−)-mearsine

The facile synthesis of a range of novel isoquinuclidinones from 6-acyl-cyclohex-2-enones is described, employing aqueous ammonia in a one-pot procedure involving initial conjugate addition of ammonia followed by cyclisation via intramolecular imine formation. The scope and limitations of the methodology are described as is an efficient synthesis of the Elaeocarpus alkaloid (−)-mearsine.