Vadimezan (CAS NO.: 117570-53-3), with its systematic name of 9H-Xanthene-4-acetic acid, 5,6-dimethyl-9-oxo-, could be produced through many synthetic methods.

Following is one of the synthesis routes:

Firstly, 2,3-Dimethylaniline (I) reacts with chloral hydrate (II) and hydroxylamine in hot aq. HCl to produce the isonitrosoacetanilide (III), which is cyclized in the presence of hot Ms-OH or H₂SO₄ to afford 6,7-dimethylisatin (IV). Next, the hydrolysis of (IV) by means of KOH and H2O2 in water affords 2-amino-3,4-dimethylbenzoic acid (V), which is diazotized with NaNO₂ and H₂SO₄ and treated with KI to provide 2-iodo-3,4-dimethylbenzoic acid (VI). Finally, the compound (VI) is condensed with the sodium salt of 2-(2-hydroxyphenyl)acetic acid (VII) in the presence of tris[2-(2-methoxyethoxy)ethyl]amine (TDA) and CuCl in DMSO to produce the precursor (VIII), which is finally cyclized by means of hot conc. aq. H₂SO₄ to furnish the target xanthene derivative.