Benzyl isocyanate → 4-(3-Benzyl-ureido)-5-methyl-thiophene-2-carboxylic acid benzyl ester

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Reaction Steps

Benzyl isocyanate (0.29 g, 2.2 mmol) was added to a stirred solution of 5-methyl-4-amino-thiophene-2-carboxylic acid benzyl ester from Example 9, Step 2 (0.5 g, 2.0 mmol) in toluene (10-15 mL) at room temperature under an inert atmosphere. After 20 minutes, the mixture was heated to reflux for 10 minutes, allowed to cool, then diluted with an equal volume of diethyl ether. After 10 minutes, the precipitate was filtered off, rinsed with ether, and dried to afford 0.5 g of 4-(3-benzyl-ureido)-5-methyl-thiophene-2-carboxylic acid benzyl ester; mp 208-209° C.

Provenance & Evidence