Synthesis of (±)-8-Oxa-3-azabicyclo[3.2.1]octan-2-thione and (±)-2-Oxa-5-azabicyclo[2.2.1]heptan-6-thione: Potential Synthons for the Preparation of Novel Heteroaryl-Annulated Bicyclic Morpholines

The bridged bicyclic morpholinethiones (±)-8-oxa-3-azabicyclo[3.2.1]octane-2-thione and (±)-2-oxa-5-azabicyclo[2.2.1]heptane-6-thione have been prepared in five and eight steps, respectively. Both compounds were derived from a respective requisite cis-disubstituted tetrahydrofuran, which was stereoselectively prepared via hydrogenation of the corresponding disubstituted furan derivatives.