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

Participants

Reaction Steps

530 mL of concentrated sulfuric acid was added to 24.91 g (0.119 mol) of the title compound of Step A while being cooled with an acetone/ice bath. The ice bath was removed, the mixture stirred for 1 hr and was then poured over crushed ice. The aqueous layer was extracted with a 1:9 mixture of diethyl ether:hexane (6×500 mL), dried (MgSO4), filtered, and evaporated to dryness to yield 11.75 g of the title compound of Step B as an oil. 1H NMR (CDCl3): δ2.3 (s,3H), 2.6 (s,3H), 2.97 (m,2H), 3.2 (m,2H), 6.9-7.1 (m,2H).

Provenance & Evidence