反应详情

温度

-78 °C

To a stirred solution of DMSO (0.4 mL, 5.2 mmol) and methylene chloride (2 mL) at −78° C. was added oxalyl chloride (0.3 mL, 3.1 mmol) dropwise. After 20 min, a solution of methyl 1-(2-hydroxyethyl)-1H-indazole-7-carboxylate (0.6 g, 2.6 mmol) from Step D above in methylene chloride (17 mL) was added and the mixture was stirred at −78° C. for 1.5 h. After N,N-diisopropylethylamine was added, the reaction was cooled to 0° C. and quenched with saturated aqueous ammonium chloride. The aqueous layer was extracted with methylene chloride and the organic extracts were dried (Na2SO4), filtered, concentrated under reduced pressure and purified by preparatory thin layer chromatography (30% ethyl acetate in hexanes) to give methyl 1-(2-oxoethyl)-1H-indazole-7-carboxylate (0.3 g, 53%): 1H NMR (500 MHz, CDCl3) δ 9.79 (s, 1H), 8.16 (s, 1H), 8.10-8.09 (m, 1H), 7.99-7.97 (m, 1H), 7.25-7.21 (m, 1H), 5.61 (s, 2H), 3.92 (s, 3H).

1. temperaturethe reaction was cooled to 0° C.
2. customquenched with saturated aqueous ammonium chloride
3. extractionThe aqueous layer was extracted with methylene chloride
4. dry with materialthe organic extracts were dried (Na2SO4)
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure
7. custompurified by preparatory thin layer chromatography (30% ethyl acetate in hexanes)