2-Amino-5-methoxy-7-phenyl-benzothiazol (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 0.1M 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+).
