3-(2,5-Dimethyl-phenylsulfanyl)-propionic acid → 5,8-Dimethyl-3,4-dihydro-2H-1-benzothiopyran-4-one

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Reaction Steps

At −10° C., 100 g (0.48 mol) of 3-[(2,5-dimethylphenyl)thio]propanoic acid were dissolved in 2200 ml of conc. sulfuric acid. The reaction solution was stirred at room temperature for 1 h and then poured onto crushed ice. The aqueous solution was extracted with a diethyl ether/hexane mixture (1:9) (6×500 ml). The combined organic phases were dried over MgSO4 and concentrated completely using a rotary evaporator.

Provenance & Evidence