Hydrochloric Acid → Ethyl 3-methyl-2,4-dioxo-1-propyl-1,2,3,4-tetrahydrothieno[2,3-d]pyrimidine-5-carboxylate

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Reaction Steps

The product of step b) (6.95 g) in dry dimethylformamide (100 ml) was added potassium carbonate (2.4 g) and stirred for 10 min. Ethyl bromopyruvate (5 ml) was added and was stirred under nitrogen at room temperature for 2 h. The reaction was poured into water (1 L), acidified (2M HCl) and extracted with ethyl acetate. The organic extracts were washed with brine (100 ml). Drying and evaporation afforded an oil. The oil was dissolved in dichloromethane (100 ml) and cooled in ice whilst stirring. Titanium tetrachloride (7.58 ml) was added and stirring continued under nitrogen for 2 h. The reaction was poured into water (1 L) and extracted with dichloromethane. The organics were dried and evaporated in vacuo. The residue was purified by chromatography (SiO2/ethyl acetate-dichloromethane 0-8%) to afford the subtitle compound as an orange oil, 4.64 g. δ 1HCDCl3 1.02 (3H, t), 1.83 (2H, sextet), 3.42 (3H, s), 3.95 (2H, t), 4.41 (2H, q), 7.30 (1H, s). MS (APCI) 297.1 (M++H)

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