Toluene → 2-Methyl-5,6-dihydro-1,4-oxathiine-3-carboxylic acid

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Reaction Steps

Ethyl 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxylate was prepared by the method of U.S. Pat. No. 3,249,499 (col. 5, lines 36-55), with the following modifications: toluene was used as the solvent instead of benzene, sodium bicarbonate was used as the base instead of potassium hydroxide, and the azeotropic removal of water was carried out under reduced pressure at about 65° C. 5,6-Dihydro-2-methyl-1,4-oxathiin-3-carboxylic acid was prepared by hydrolysis of the ester as described in the same patent (col. 5, lines 56-68, where the acid is named 2,3-dihydro-5-carboxy-6-methyl-1,4-oxathiin).

Provenance & Evidence