Synthesis of macrosphelides H and G

A compound with furyl and vinyl groups was designed as an intermediate for synthesis of macrosphelide H. The furyl group was oxidatively transformed into the key C(5)–O(10) part by a two-step conversion of (1) NBS, H2O; (2) NaClO2 without affecting the free hydroxyl group at C(3), thus furnishing the seco acid, while the Wacker oxidation at the final step was used to convert the vinyl group into acetyl group to afford macrosphelide H. This strategy was applied successfully to synthesis of macrosphelide G as well.