Mankind has been searching for anticancer drugs from nature and artificial compounds. Since the discovery of englerin A, a guaiane sesquiterpene possessing the characteristic tricyclic 5-6-5 fused ring framework with contiguous seven stereogenic centers and isolated from Phyllanthus engleri, many synthetic groups have enthusiastically launched and accomplished its the chemical synthesis. All the synthetic groups focused on how to efficiently construct the tricyclic framework containing oxygen bridge with various approaches. In this review, the total and formal syntheses of englerin A reported to date are summarized. . Theodrakis' formal synthesis of (À )-englerin A (1) via [4 + 3] cycloaddition.Scheme 6. Chain's total synthesis of (À )-englerin A (1) via Michael addition and reductive carbonyl-enone cyclization. . Parker's formal synthesis of (À )-englerin A (1) via relay RCM.Scheme 8. Cook's formal synthesis of (�)-englerin A (1) via reductive Mizoroki-Heck cyclization.

Englerin A, a guaiane sesquiterpene isolated from Phyllanthus engleri, showed highly potent and selective growth inhibitory activities against renal cancer cell lines. We synthesized the key tricyclic intermediate from commercially available 2,2-dimethyl-1,3-dioxan-5-one via regio- and diastereoselective [4+3] cycloaddition between the formyl enol silyl ether and the disubstituted furan, in 4.8% total yield over 10 steps.