Sulfuric Acid → ethyl 10,11-dihydro-5-oxo-5H-dibenzo[a,d]cycloheptene-2-carboxylate

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Reaction Steps

[step 1] 5-Oxo-10,11-dihydro-5H-dibenzo[a,d]cycloheptene-2-carboxylic acid (JP-B-2526005, 19.9 g, 79 mmol) and triethyl orthoformate (17.0 mL, 102 mmol) were dissolved in ethanol (130 mL), followed by adding concentrated sulfuric acid (1.68 mL, 32 mmol) and the mixture was stirred under reflux for 12 hr. The mixture was diluted with ethyl acetate, and the organic layer was washed with saturated aqueous sodium hydrogen carbonate solution, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=90/10) to give ethyl 5-oxo-10,11-dihydro-5H-dibenzo[a,d]cycloheptene-2-carboxylate (20.8 g, 94%).

Provenance & Evidence