Synthesis of (±)-6-oxa-3-azabicyclo[3.1.1]heptan-2-thione: a potential synthon for the preparation of novel heteroaryl-annulated bicyclic morpholines

The novel bridged bicyclic morpholinethione (±)-6-oxa-3-azabicyclo[3.1.1]heptan-2-thione (9) has been prepared in six steps. This conformationally restricted morpholinethione was prepared stereoselectively using straightforward chemistry and inexpensive starting materials. The key oxetane ring was formed via an intramolecular alkylation reaction.