Total synthesis of the immunosupressant (-)-pironetin (PA48153C).

[reaction: see text]. Total synthesis of the immunosuppresant pironetin has been achieved by a synthetic route in which the connections between starting materials and the desired structure are readily discerned. Key steps include a diastereoselective Lewis acid mediated crotylstannane aldehyde addition, a highly selective Lewis acid promoted Mukaiyama aldol reaction, an anti-selective SmI2 reduction of a beta-hydroxyketone, and finally a lactone annulation reaction.