Vanillic Acid → 2-(4-Hydroxy-3-methoxyphenyl)benzothiazole

Participants

Reaction Steps

A slurry of 2-aminothiophenol (357 mg, 2.85 mmol) in polyphosphoric acid (14.0 g) was heated to 110° C. and 4-hydroxy-3-methoxybenzoic acid (480 mg, 2.85 mmol) was added. After 2 h, the reaction mixture was cooled to rt. The mixture was poured carefully into ice cold water, and the solution was neutralized with KOH (3 M aqueous solution). The aqueous phase was extracted with EtOAc (2×). The combined organic layers were washed with Na2CO3 (1 M aqueous solution), HCl (1 M aqueous solution) and water, dried, and concentrated under reduced pressure. Purification by silica gel chromatography gave 22 mg (3%) of the title compound as an oil. 1H NMR (400 MHz, CDCl3): δ 8.02 (d, 1H), 7.88 (d, 1H), 7.72 (s, 1H), 7.55 (d, 1H), 7.48 (m, 1H), 7.36 (m, 1H), 7.00 (d, 1H), 5.92 (s, 1H), 4.03 (s, 3H).

Provenance & Evidence