Dimethyl Sulfoxide → methyl 1-(2-oxoethyl)-1H-indazole-7-carboxylate

Participants

Reaction Conditions

Reaction Steps

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).

Provenance & Evidence