Synthesis of 2,5-dihalothiazole-4-carboxylates

An efficient synthesis of 2,5-dihalothiazole-4-carboxylates has been described. Halogenation of aminothiazole carboxylate with NBS or NCS and subsequent diazotization with isoamyl nitrite and halogenation with CuBr2, CuCl2 or CH2I2 provided the corresponding diahalothiazole derivatives. The four-step process described is amenable to scale-up and requires no chromatographic purification in all the steps.