Hydrochloric Acid → 6,7-Dihydroxy-4-thiaoctanoic acid methyl ester

To a solution of 3,4-epoxy-2-butanol as obtained in Reference Example 43 (1.13 g) in methylene chloride (4 ml), methyl 3-mercaptopropionate (2.00 ml) and sodium methylate (260 μl) were added under ice cooling conditions, followed by stirring at room temperature for 1 day. To the reaction mixture, 1N hydrochloric acid was added, and the mixture was extracted with ethyl acetate; the solvent was distilled off under reduced pressure. The resulting residue was purified by silica gel column chromatography (ethyl acetate:hexane=2:1) to yield the title compound (1.47 g, yield 55%) as a colorless oily substance.