Trifluoromethanesulfonic anhydride → 3-Bromo-5-(morpholin-4-yl)-7H-thieno[3,2-b]pyran-7-one

Participants

Reaction Steps

An oven-dried 100 mL round-bottom flask was charged with a magnetic stirring bar, 1-(4-bromo-3-hydroxythiophen-2-yl)-3-morpholinopropane-1,3-dione (1.95 g, 5.83 mmol) and dissolved in dichloromethane (30 mL) under magnetic stirring. Trifluoromethanesulfonic anhydride (2.45 mL, 14.6 mmol) was added portionwise over 2 minutes, and the reaction was stirred at room temperature. After stirring overnight, the reaction was concentrated in vacuo and redissolved in methanol (10 mL). After stirring for 4 hours, the reaction was concentrated in vacuo and diluted with aqueous 5% sodium bicarbonate solution (100 mL). The reaction was transferred to a separatory funnel and extracted three times with dichloromethane (100 mL). The organic layers were combined, dried over magnesium sulfate, filtered, and concentrated in vacuo to give 3-bromo-5-morpholino-7H-thieno[3,2-b]pyran-7-one (103) (1.52 g, 4.81 mmol, 82%) as a brown solid.

Provenance & Evidence