Tetrabutylammonium Fluoride → 4-Ethynyl-3-methyl-benzofuran-2-carboxylic acid ethyl ester

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Reaction Steps

To the product of Example 33, Step 1, 3-methyl-4-trimethylsilanylethynyl-benzofuran-2-carboxylic acid ethyl ester (1.5 g, 4.99 mmol, 1 eq), in THF (10 mL) under argon, was added tetrabutylammonium fluoride (1.0 M in THF, 6 mL, 5.99 mmol, 1.2 eq.) and the reaction was stirred at ambient temperature for 45 minutes. After work-up and flash column chromatography, 4-ethynyl-3-methyl-benzofuran-2-carboxylic acid ethyl ester was obtained in 35% yield. 1H NMR (400 MHz, DMSO-d6) δ ppm 1.4 (t, J=7.1 Hz, 3 H) 2.8 (s, 3 H) 4.4 (m, J=7.1, 7.1, 7.1 Hz, 2 H) 4.6 (s, 1 H) 7.5 (m, 2 H) 7.7 (dd, J=7.7, 1.4 Hz, 1 H).

Provenance & Evidence