3-Chlorothieno[3,2-b]pyridine-5,6-dicarboxylic acid → 3-Chlorothieno[3,2-b]pyridine-5,6-dicarboxylic acid anhydride

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Reaction Steps

3-Chlorothieno[3,2-b]pyridine-5,6-dicarboxylic acid (1.45 g) is heated at 85° to 90° C. for 30 minutes then 90° to 102° C. for 30 minutes in acetic anhydride (7 mL). The reaction is cooled, the solids filtered off and washed with ether to give 1.2 g of 3-chlorothieno[3,2-b]pyridine-5,6-dicarboxylic acid anhydride. The proton magnetic resonance spectrum is consistant with the structure.

Provenance & Evidence