Sulfuric Acid → 5,8-Dimethyl-6-bromothiochroman-4-one

Participants

Reaction Conditions

Reaction Steps

19.50 g (67.4 mmol) of the title compound of Step A was dissolved in 156 mL of dichloromethan and cooled to 5° C. 78 mL of concentrated sulfuric acid was added dropwise over 45 minutes with vigorous stirring and the reaction was then allowed to stir at 5° C. for 1.5 hours. The reaction was poured into 500 mL of ice water, the layers were separated and the aqueous phase extracted twice with 300 mL of dichloromethane. The combined organic layers were washed twice with 1.0 N NaOH, once with water. dried over magnesium sulfate and concentrated under reduced pressure to yield 16.04 g of the title compound of Step B as a yellow solid melting at 86-87° C. 1H NMR (CDCl3): δ2.26 (s, 3H), 2.59 (s, 3H), 3.00 (t, 2H), 3.19 (t, 2H), 7.45 (s, 1H).

Provenance & Evidence