反应详情

温度

-20 °C

To a solution of (1,6-dihydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl)-acetic acid ethyl ester (1.5 g, 6.0 mmol) and 2-bromo-5-nitro-[1,3,4]thiadiazole (2.52 g, 12.0 mmol) at −20° C. was added K2CO3 (1.65 g, 12.0 mmol). The reaction mixture was stirred for 10 hours at −20° C. then concentrated in vacuo. The residue was dissolved in EtOAc (20 mL), washed with water (2×10 mL), dried and concentrated. The residue was purified by silica gel flash column chromatography to give a mixture of products (5:2 nitro:bromide, 1.6 g). This was further purified by preparative HPLC to give [6-(5-bromo-[1,3,4]thiadiazol-2-yloxy)-1-hydroxy-4-methyl-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester (0.34 g, 14%) and [1-hydroxy-4-methyl-6-(5-nitro-[1,3,4]thiadiazol-2-yloxy)-1,3-dihydro-benzo[c][1,2]oxaborol-3-yl]-acetic acid ethyl ester (0.6 g, 26%).

1. concentrationthen concentrated in vacuo
2. dissolutionThe residue was dissolved in EtOAc (20 mL)
3. washwashed with water (2×10 mL)
4. customdried
5. concentrationconcentrated
6. customThe residue was purified by silica gel flash column chromatography
7. customto give
8. customThis was further purified by preparative HPLC