2-Nitrobenzoic acid → 3-formyl-5,8-dimethoxy-2H-chromene-2-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

(E)-4-oxo-but-2-enoic acid ethyl ester (7.30 mL, 60.37 mmol), 2-nitro benzoic acid (1.852 g, 10.98 mmol), and pyrrolidine (0.91 mL, 10.98 mmol) were added simultaneously to a solution of commercially available 2-hydroxy-3,6-dimethoxy-benzaldehyde (10.0 g, 54.89 mmol) in dimethysulfoxide (50 mL) at 25° C. and the solution was stirred for 78 hours at 25° C. The reaction was quenched by the addition of water. The reaction mixture was then partitioned between water and ethyl acetate. The combined organics were washed with a saturated brine solution, dried over anhydrous sodium sulfate, filtered, rinsed and concentrated in vacuo. The residue obtained was purified on a silica gel flash column chromatography using ethyl acetate-hexanes (1:1.2) as eluents, yielding 3-formyl-5,8-dimethoxy-2H-chromene-2-carboxylic acid ethyl ester (3.5 g, 62.3%).

Provenance & Evidence