Methyl 7-chloro-2,3-dihydro-8-methoxy-1,4-benzodioxin-5-carboxylate → 7-Chloro-2,3-dihydro-8-methoxy-1,4-benzodioxin-5-carboxylic acid

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Reaction Steps

A mixture of intermediate (2) (0.138 mol) in a 2N NaOH solution (500 ml) was stirred and refluxed for 1 hour, then cooled and washed with DCM. The mixture was separated into its layers. The aqueous layer was acidified with a concentrated HCl solution until pH=2. The solid was filtered off, washed with water and dried in vacuo. A part (2.5 g) of this fraction was crystallized from methanol. The precipitate was filtered off and dried, yielding 0.88 g of 7-chloro-2,3-dihydro-8-methoxy-1,4-benzodioxin-5-carboxylic acid (intermediate 3, mp. 172° C.).

Provenance & Evidence