Naphthalic anhydride → 8-(6-Ethylamino-3-ethylimino-2,7-dimethyl-3H-xanthen-9-yl)naphthalene-carboxylic acid

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Reaction Steps

3-Ethylamino-4-methyl-phenol (0.3 g, 2 mmol) and benzo[de]isochromene-1,3-dione (0.2 g, 1 mmol) in sulfuric acid (3 ml) was heated to 150° C. over a period of 6 h. The reaction mixture was pouring into crushed ice, allowed to stand over a period of 1 h and the precipitate was filtered. The filtrate was neutralized with concentrated ammonium hydroxide and concentrated to give a dark purple residue. Purification via preparatory layer chromatography (PLC, 1 mm silica gel, 9/1 DCM: MeOH, 2% AcOH) gave the title compound (50 mg). ABS λmax=527 nm (EtOH).

Provenance & Evidence