Intramolecular Schmidt reactions of azides with carbocations: synthesis of bridged-bicyclic and fused-bicyclic tertiary amines

Aliphatic azides were captured intramolecularlyby carbocations, producing aminodiazonium ion intermediates. Carbon-to-nitrogen rearrangement then occurred, generating bridged- or fused-bicyclic a-amino carbocations or iminium ions, depending on the geometry about the C(+)-N bond. In the bridged systems, rapid elimination of the α-amino carbocations produced twisted enamines with 1-azabicyclo[3.2.2]nonene, 1-azabicyclo[2.2.2]octene, and 1-azabicyclo[3.2.1]octeneskeletons. In the fused systems, the iminium ions were reduced with sodium borohydridetogive 1-azabicyclo [n.3.0]alkanes, where n=4 or 5. The carbocations for these intramolecular Schmidt reactions were generated by treatment of alkenes or alcohols with trifluoromethanesulfonic acid