Asymmetric total syntheses of passifetilactones A, C, E and 4-<i>epi</i>-passifetilactone B

This paper describes the efficient asymmetric total syntheses of passifetilactones A, C, E and 4-<i>epi</i>-passifetilactone B. Keck allylation and ring-closing metathesis (RCM) have been employed as the key steps in the synthesis of passifetilactones A and C, while Sharpless kinetic resolution (SKR) and RCM have been utilized in the syntheses of passifetilactone E and 4-<i>epi</i>-passifetilactone B. The total syntheses of passifetilactones A, C, E and 4-<i>epi</i>-passifetilactone B required 8, 4, 8 and 10 steps with good overall yields of 37.4%, 60%, 10.2% and 3.5%, respectively. The synthesis efforts also established the absolute structures of these molecules.