Triethylamine → 4-Cyclopropylethynyl-3-methyl-benzofuran-2-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To the product of Example 20, Step 1, 3-methyl-4-trifluoromethanesulfonyloxy-benzofuran-2-carboxylic acid ethyl ester (1.8 g, 5.1 mmol, 1 eq), in 2 mL of DMF under nitrogen was added 200 mg of PdCl2(PPh3)2 (0.28 mmol, 0.05 eq), Et3N (2.85 mL, 20.4 mmol, 4 eq), cyclopropylethynyl-trimethylsilane (1 g, 7.2 mmol, 1.4 eq), and tetrabutylammonium fluoride (5.1 mL, 1.0 M in THF, 5.1 mmol, 1 eq). The reaction mixture was sealed and heated to 80° C. for 12 h. After workup and column chromatography (2% ethyl acetate/hexane), 4-cyclopropylethynyl-3-methyl-benzofuran-2-carboxylic acid ethyl ester was obtained in 15% yield (202.6 mg). 1H NMR (400 MHz, CD3OD) δ ppm 0.7 (m, 2 H) 0.9 (m, 2 H) 1.3 (t, J=7.1 Hz, 3 H) 1.5 (m, 1 H) 2.7 (s, 3 H) 4.3 (q, J=7.2 Hz, 2 H) 7.2 (m, 1 H) 7.3 (dd, J=8.3, 7.3 Hz, 1 H) 7.4 (m, 1 H).

Provenance & Evidence