Carbon Dioxide → 2,3-Dihydro-1-benzofuran-7-carboxylic acid

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Reaction Conditions

Reaction Steps

N,N,N′,N′-Tetramethylethylenediamine (38 ml) was dissolved in hexane (300 ml), cooled in an ice-bath and n-butyllithium (100 ml of a 2.5M solution in hexane) added. The mixture was stirred at 0°C. for 15 minutes before adding 2,3-dihydrobenzo[b]furan (30 g) dropwise over 30 minutes. The mixture was allowed to warm to room temperature over 30 minutes, stirred at room temperature for a further 4 hours, poured onto an excess of solid carbon dioxide and left to stand for 3 days by which time the solvent had evaporated off. The residue was partitioned between ethyl acetate (1L) and 4N aqueous hydrochloric acid solution (240 ml), the layers separated and the aqueous layer extracted with ethyl acetate (500 ml). The organic extracts were combined, dried over anhydrous sodium sulphate and the solvent removed under reduced pressure. The residue was then triturated with diethyl ether to give 2,3-dihydrobenzo[b]furan-7-oic acid as a white solid (21 g).

Provenance & Evidence