Synthesis of 6-isomer of 5,8-O-dimethyl ether of shikonin (13), a promising anticancer scaffold, always remains a huge challenge. Herein a key intermediate for 13, 2-(1-hydroxyl-4-methyl-3-pentenyl)-1,4,5,8-tetramethoxynaphthalene (10), was obtained on the large-scale synthesis. A ring-closing/ring-opening strategy was applied to avoid the undesired reactivity posed by the side chain and racemization of the chiral centre. Incorporation of bulky substituent 4-((tertbutoxycarbonyl)amino)phenyl to hydroxyl group in the side chain redistributed ele...
