Saponaceolides: Differential Cytotoxicity and Enantioselective Synthesis of the Right-hand Lactone Moiety

The enantioselective synthesis of the right-hand lactone moiety 5 of saponaceolide B, 2, is described. The mean graph profiles of 5 do not match the characteristic patterns of differential cytotoxicity of saponaceolides A, 1, and B, 2, in the NCI human disease-oriented tumor screening panel, pointing out the need of the entire saponaceolide structure for maintaining the specificity and potency of the antitumor activity. En route to 5 several useful chiral building blocks, such as compounds 6, 10, 19, 27, and 28 were prepared.