Efficient, asymmetric synthesis of (−)-isooncinotine

Asymmetric synthesis of (−)-isooncinotine, a 22-membered lactam of spermidine alkaloid, starting from resolution of 2-piperidineethanol with (S)-10-camphorsulfonic acid is reported. Michael addition, amidations, and aluminum hydride reduction were applied to form the moiety of spermidine. Retro-Michael addition was observed when β-amido- and β-amino-propionitriles were reduced by LAH. The effects of LAH versus AlH3 were discussed. The synthesis of the skeleton of this macrolide is achieved with ring-closing metathesis of the diene prepared from acylation of the spermidine.