Sulfuric Acid → Methyl 4-amino-5-chloro-2,3-dihydrobenzofuran-7-carboxylate

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Reaction Steps

Sulfuric acid (18 ml) was added dropwise to cooled methanol (90 ml). 4-Amino-5-chloro-2,3-dihydro-7-benzofurancarboxylic acid (20 g) was added to the mixture which was subsequently stirred and refluxed for 3 hours. The reaction mixture was cooled and alkalized with CH3OH/NH3. The solvent was evaporated and the residue stirred in water. The precipitate was filtered off and washed with water and DIPE. The remaining solid was dried, yielding 17.2 g (81%) of methyl 4-amino-5-chloro-2,3-di-hydro-7-benzofurancarboxylate (intermediate 1; mp. 135.4° C.).

Provenance & Evidence