2-Amino-5-methoxy-7-phenylbenzothiazol (45 mg, 0.18 mmol) is dissolved in dichloromethane (2 ml) and subsequently treated with triethylamine (0.073 ml, 0.53 mmol) and 5-methyl-thiophene-2-carbonyl chloride (56 mg, 0.35 mmol). After 6 h, further 0.073 ml, 0.53 mmol) and 5-methyl-thiophene-2-carbonyl chloride (56 mg, 0.35 mmol) are added and the mixture is stirred for additional 18 h at ambient. After addition of 0.1 M aqueous sodium hydroxide, the mixture is stirred for additional 16 h. The organic layer is separated, dried and evaporated to dryness. Flash chromatography (silica, eluent ethyl acetate/cyclohexane 1:1, containing 0.5% of 25% aqueous ammonia) affords (10 mg, 5%) of the product as white solid. MS: m/e=380 (M+).
