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Total synthesis of the immunosuppresant pironetin has been achieved by a sy
nthetic route in which the connections between starting materials and the d
esired structure are readily discerned, Key steps include a diastereoselect
ive Lewis acid mediated crotylstannane aldehyde addition, a highly selectiv
e Lewis acid promoted Mukaiyama aldol reaction, an anti-selective Sml(2) re
duction of a beta -hydroxyketone, and finally a lactone annulation reaction
.