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

Beteiligte Stoffe

Reaktionsschritte

N,N,N',N'-Tetramethylethylenediamine (231.4 g) was added at ambient temperature to a solution of n-butyl lithium (2.5M, 800 ml) in hexane (2.5 l) followed by a solution of 2,3-dihydrobenzo[b]furan (102 g) in hexane (25 ml). The mixture was stirred under nitrogen at ambient temperature for 5 hours. The resulting suspension was added slowly to dry ice (300 g) and hexane (500 ml) under nitrogen. After stirring at ambient temperature for 16 hours, the mixture was diluted with water (2 l), and the layers separated. The aqueous layer was washed with hexane, acidified to pH 1 with concentrated hydrochloric acid, cooled and the precipitate collected by filtration. This was washed with water and dichloromethane and dried at 80° C. in vacuo to give 2,3-dihydrobenzo[b]furan-7-carboxylic acid (39.6 g), m.p. 164°-165° C. The hexane layer was filtered, dried over sodium sulphate and concentrated. On cooling, further product was obtained (32.7 g), m.p. 170° C.

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