Perchloric Acid → ethyl 2-[4-(3,4-dihydro-2H-1-benzopyran-6-yl)-2,5-dimethyl thiophen-3-yl]-tert-butoxy-acetate

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Reaction Steps

Under a nitrogen atmosphere, perchloric acid (70%, 1.5 mL) was added at −10° C. to a solution of ethyl 2-[4-(3,4-dihydro-2H-1-benzopyran-6-yl)-2,5-dimethyl thiophen-3-yl]-2-hydroxyacetate (17e) (88 mg, 0.25 mmol) in tert-butyl acetate (10 mL). After 1 hour, the reaction was quenched with a saturated aqueous solution of sodium carbonate and extracted with dichloromethane (2×30 mL). The organic layer was washed with brine (20 mL), dried over sodium sulfate, filtered and evaporated under reduced pressure. The residue was purified by flash chromatography on silica gel (dichloromethane)) to afford the desired product (17f) as a white solid (43 mg, 0.11 mmol, 43%).

Provenance & Evidence