Ethanol → Methyl 7-hydroxy-2-methyl-2,3-dihydro-1,4-benzodioxine-2-carboxylate

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Reaction Steps

The product from Step 5 (0.6 g, 2.9 mmol) was treated with 2 N KOH in ethanol under reflux for 4 h. Removal of ethanol and acidification of the residue with 2 N HCl gave the crude acid, which was dissolved in dichloromethane (mL) and treated with boron tribromide (1 M in hexane, mL, mmol) at 0 C for 1 h. The reaction was quenched with water and extracted with dichloromethane. The combined extracts were washed with brine and dried over MgSO4. Removal of solvents gave a residue which was taken up in 7:1 benzene/methanol and treated with excess trimethylsilyldiazo methane (1 m in hexane). Removal of solvents and purification of the residue by chromatography on silica gel afforded 0.48 (75% yield) of the title compound as an oil.

Provenance & Evidence