Diastereoselective Construction of the 6-Oxa-2-azabicyclo[3.2.1]octane Scaffold from Chiral α-Hydroxyaldehyde Derivatives by the Aza-Prins Reaction.

(R)-2,3-Di-O-benzylglyceraldehyde and N-tosyl homoallylamine undergo aza-Prins cyclization to afford (1R,5S,7S)-7-[(benzyloxy)methyl]-2-tosyl-6-oxa-2-azabicyclo[3.2.1]octane in a highly diastereoselective manner through an unexpected intramolecular nucleophilic attack. Our work has opened a new route toward the asymmetric synthesis of 7-(alkyl or aryl)-6-oxa-2-azabicyclo[3.2.1]octane derivatives from chiral α-hydroxyaldehyde derivatives in one step.