A Cascade Aza-Cope/Aza-Prins Cyclization Leading to Piperidine Derivatives

The cascade aza-Cope/aza-Prins cyclization of homoallylamines to give substituted piperidines has been explored. The use of glyoxalic acid as the carbonyl component afforded bicyclic structures as a result of the internal carboxylate anion trapping the intermediate cation. The unimolecular bis-, tris-, and tetrakis(homoallylamine)s efficiently delivered the appended bis-, tris- and tetrakis(piperidine-4-ol)s (tripod and crucifix shape, respectively) as new entities. The latter compound served as an excellent ligand in the Suzuki-Miyaura cross-coupling reaction to synthesize incrustoporin