Dabco → Methyl 4-bromo-3-[(dimethylamino)thioxomethoxy]-5-methyl-2-thiophenecarboxylate

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Reaction Steps

Methyl 4-bromo-3-hydroxy-5-methyl-2-thiophenecarboxylate (2.5 g, 10 mmoles) is stirred under argon in DMF (20 mL). Dimethylthiocarbamyl chloride (2.65 g, 21 mmoles) and 1,4-diazabicyclo[2.2.2]octane (2.4 g, 21 mmoles) are added. The mixture is stirred at room temperature for 2 hours, then at 50° C. for 20 hours, then poured into ice water (200 mL) and extracted twice with toluene. The combined extracts are washed successively with 2N HCl, water, 0.5 M NaHCO3, and water, then dried over MgSO4. Removal of the solvent under reduced pressure, followed by recrystallization from ethyl acetate affords the product (2.7 g); mp 152°-154° C.

Provenance & Evidence