Cesium carbonate → [6-(5-Carbamoyl-pyrazin-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

A suspension of (1,6-dihydroxy-4-methoxymethyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid ethyl ester (150 mg, 0.600 mmol) and Cs2CO3 (430 mg, 1.32 mmol) in DMF (4 mL) was treated with 5-bromo-pyrazine-2-carboxylic acid amide (158 mg, 0.780 mmol) at room temperature and the reaction was heated to 80° C. for 2 h. The reaction mixture was concentrated to dryness. The residue was diluted with water and adjusted to pH 2 with 1N HCl. The aqueous phase was extracted with ethyl acetate. The organic phase was separated, dried (Na2SO4), and concentrated. The residue was purified by the flash column chromatography (silica, hexanes/ethyl acetate=1:2 to DCM/MeOH=10:1) to afford the title compound as a white solid (110 mg). 1H NMR (300 MHz, CD3OD) δ 8.90 (s, 1H), 8.34 (s, 1H), 7.48 (s, 1H), 7.35 (s, 1H), 7.08 (s, 1H), 5.70 (s, 1H), 5.69-5.66 (m, 1H), 4.21 (q, 2H), 3.14-3.12 (m, 1H), 2.49-2.41 (m, 1H), 2.37 (s, 3H), 1.26 (t, 1H). MS found: (M+H)+: 372.2.

Provenance & Evidence