Hydrochloric Acid → HCID 10469837, compound

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Reaction Steps

To dimethyl carbonate (87 g) is added sodium methoxide (10.5 g), to the mixture is added 7,8-dimethoxy-3,4-dihydro-1-benzothiepin-5(2H)-one(11.0 g) obtained in Reference Example 7. The mixture is heated for two hours under reflux. The reaction mixture is poured into ice-water and acidified (pH 3) with 2N hydrochloric acid, followed by extraction with ethyl acetate. The organic layer is washed with a saturated aqueous saline solution, dried, and concentrated under reduced pressure. The residue is recrystallized from hexane - methylene chloride to afford methyl 7,8-dimethoxy5-oxo-2,3,4,5-tetrahydro-1-benzothiepin-4-carboxylate as colorless needles (10.8 g), m.p. 132°-133° C.

Provenance & Evidence