From mannose to morphan analogues: methyl α-d-mannoside as chiral building block for the synthesis of mono- and bicyclic σ receptor ligands

► Synthesis of mannose derived σ1 ligands. ► Axial amines are considerably less potent than equatorial amines. ► Synthesis of oxa-morphan analogues by acid catalyzed cyclization of an azide. ► Unexpected σ1 affinity of oxa-morphan despite the absence of a basic amino group.