Carbon Dioxide → 2,3-Dihydro-5-phenyl-4-benzofurancarboxylic acid

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Reaction Steps

A magnetically stirred solution of 2,3-dihydro-4-iodo-5-phenylbenzofuran (1.60 g, 4.97 mmol) in anhydrous THF (40 mL) under nitrogen at -78° C. was treated with tert-butyllithium (1.73 M in pentane, 6.10 mL, 10.6 mmol), keeping the temperature less than -65° C., throughout. The solution was stirred for 0.5 h and treated with anhydrous carbon dioxide over 1 h at such a rate as to keep the temperature below -60° C. during addition. The solution was stirred for 2 h, allowed to warm to room temperature, and treated with Et2O, ice (100 g), and 1 N NaOH (200 mL). The layers were separated and the organic portion was further extracted with fresh 1 N NaOH (2×200 mL). The combined organic extracts were acidified with concentrated HCl, extracted with CH2Cl2 (3×150 mL), and the extracts washed with brine (200 mL), dried (MgSO4), filtered, and concentrated in vacuo to give 0.795 g (67%) of the title compound: 1H NMR (300 MHz, CDCl3)δ 3.45 (t, J=8.5 Hz, 2H), 4.65 (t, J=8.5 Hz, 2H), 6.93 (d, J=8 Hz, 1H), 7.14 (d, J=8 Hz, 1H), 7.29-7.42 (m, 5H), 11.2 (br s, 1H).

Provenance & Evidence