Hydrogen Bromide → KOJIC ACID, 2-BROMOMETHYL ANALOG

Participants

Reaction Conditions

Reaction Steps

In a 250 mL round-bottomed flask 5-hydroxy-2-(hydroxymethyl)-4H-pyran-4-one (10.0 g, 70.36 mmol) was added to concentrated H2SO4 (30 mL). The solution was cooled to 4° C. and bromohydric acid (40 mL) was added dropwise for 1.5 h. HBr vapors were trapped using a NaOH 0.5 N solution. The reaction was stirred at 70° C. for 18.5 h. After cooling ice (220 g) was added with continuous stirring for for 1.5 h to obtain a white precipitate. The solid was filtered off and dissolved in ethyl acetate and the solution was dried with MgSO4, filtered and evaporated. 2-(Bromomethyl)-5-hydroxy-4H-pyran-4-one 21 was obtained as a pale yellow solid (9.1 g, 63% yield).

Provenance & Evidence