Carbon Dioxide → spiro[2H-1-benzopyran-2,1'-cyclopropane]-6-carboxylic acid

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Reaction Steps

Following general procedure R and using 6-bromo-8-cyclopropyl-3,4-dihydro-4,4-dimethylspiro[2H-1-benzopyran-2,1′-cyclopropane] (Intermediate 42, 0.45 g, 1.48 mmol), anhydrous tetrahydrofuran (5 mL), 1.7M solution of tert-butyl lithium solution in pentane (1.74 mL, 2.96 mmol) and carbon dioxide generated from dry ice, followed by flash column chromatography over silica gel (230-400 mesh) using 50% ethyl acetate in hexane as the eluent, the title compound was obtained as a white solid (0.34 g, 85%).

Provenance & Evidence