107818-55-3

22288-78-4

107818-55-3

The general procedure for the synthesis of methyl 3-amino-5-bromothiophene-2-carboxylate from methyl 3-amino-2-thiophenecarboxylate is as follows: Example 1: Synthesis of N-(3-aminopropyl)-N-[1-(3-benzyl-6-bromo-4-oxo-3,4-dihydrothieno[3,2-d]pyrimidin-2-yl)-2-(dimethylamino)-2-oxoethyl]-4-methylbenzamide (Compound 5 in Table 1) Step 1. Synthesis of methyl 3-amino-5-bromothiophene-2-carboxylate Methyl 3-amino-2-thiophenecarboxylate (1 eq., 25 g) was dissolved in a mixed solvent of 250 ml of dichloromethane and 250 ml of methanol, phenyltrimethylammonium tribromide (3 eq., 180 g) was added followed by calcium carbonate (in appropriate amount). The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the calcium carbonate was removed by filtration and the filtrate was concentrated under reduced pressure. To the concentrated filtrate was added water (750 ml) and then extracted with ethyl acetate (1 L). The ethyl acetate layer was washed sequentially with water, sodium thiosulfate solution, saturated sodium bicarbonate solution and saturated sodium chloride solution. The organic layer was dried with magnesium sulfate, filtered and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by fast chromatography to afford 21.46 g (57% yield) of methyl 3-amino-5-bromothiophene-2-carboxylate as a light brown oil, the mass spectrum showed MH+ = 238.1.