Toluene → Methyl 1-benzofuran-2-carboxylate

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Reaction Conditions

Reaction Steps

The crude product 2 was placed into a 5-liter 3-necked round-bottomed flask equipped with a mechanical stirrer and a water trap. Toluene (1,900 ml) was added and the solution heated at reflux temperature (111° C.) until all water had been removed. Diazabicyclounde-7-ene (DBU) (65 g) was then added and the mixture was stirred at 111° C., without the water trap, until the starting material was no longer present, i.e., was not detectable by TLC monitoring. Most of the solvent (90%) was then distilled off. The residue was cooled to 25° C., and ethyl acetate (1,000 ml) was added. The mixture was transferred to a separatory funnel and the organic solution washed with 2N HCl (2×1,000 ml), then with water (1,000 ml). Drying was done over magnesium sulfate. The crude product (326.56 g) was a dark oil and was used directly in the next step. A small sample was purified for the purpose of structure elucidation: the crude material (2 g) was dissolved in ethyl ether and washed with 1N KOH. Drying was done over magnesium sulfate, the material was filtered, and the solvent evaporated. The oily residue was crystallized from isopropanol. The melting range is 53.8°-54° C.

Provenance & Evidence