5,7-Dimethoxy-4-methylphthalide and 5,7-dihydroxy-4-methylphthalide, two key intermediates in the synthesis of mycophenolic acid, were prepared from 3,5-dimethoxybenzyl alcohol in a five-step sequence with yields of 80% and 72%, respectively. The key process involved a transformation of 6-chloromethyl-2,4-dimethoxybenzaldehyde to 5,7-dimethoxyphthalide by an oxidation with sodium chlo-rite and a concomitant lactonization in one pot.

Key words: 5,7-dihydroxy-4-methylphthalide, mycophenolic acid, synthesis, 5,7-dimethoxy-4-methylphthalide