Total synthesis of thapsigargin, a potent SERCA pump inhibitor

The enantioselective total synthesis of thapsigargin, a potent, selective inhibitor of the Ca2+ pump SERCA, is described. Starting from ketoalcohol 8, key steps involve regioselective introduction of the internal olefin at C4-C5, judicious protecting group choice to allow chelation-controlled reduction at C3, and chemoselective introduction of the angelate ester function at C3-O. A selective esterification approach completes the total synthesis in a total of 42 steps and 0.61% overall yield (88.6% average yield per step). [reaction: see text].