Total synthesis of Palmarumycin BGs, C₁ and Guignardin E

The first total synthesis of Palmarumycin BG1-3, BG5-6, C₁ and Guignardin E (1-7) were achieved by the same intermediate Palmarumycin C₂ through a N-benzyl cinchoninium chloride-catalyzed epoxidation, an organoselenium-mediated reduction, and a cerium(iii) chloride hydrate-promoted regioselective ring-opening and elimination of cyclic α,β-epoxy ketone as the key steps via6-7 step routes using 1,8-dihydroxynaphthalene (DHN) and 5-methoxytetralone as the starting materials in overall yields of 1.0-17.4%, respectively. Their structures and absolute configurations were characterized and determined by ¹H, ¹³C NMR, IR, HR-ESI-MS and X-ray diffraction data. These compounds displayed significant inhibition activities against HCT116, U87-MG, HepG2, BGC823 and PC9 cell lines.