Dimethyl oxalate → (1,5-dimethyl-1H-indol-7-yl)-oxo-acetic acid methyl ester

Participants

Reaction Steps

A solution of 1,5-dimethyl-7-bromoindole (4.27 g, 19.05 mmol) in THF (130 mL) was cooled to −78° C. and a solution of tert-butyl lithium in pentanes (1.7 M, 24.6 mL, 41.8 mmol) added dropwise over 30 min. After 30 min at −78° C., the mixture was treated with dimethyl oxalate (5.62 g, 47.6 mmol) in one portion. After 15 min, the mixture was allowed to warm to room temperature and stirred 4 h. The reaction mixture was quenched with water, extracted with ethyl acetate, and the extracts washed with brine, dried (Na2SO4) and concentrated. Flash chromatography (EtOAc/hexanes) afforded the title compound (4.2 g, 95%) as bright yellow oil. 1H NMR (400 MHz, CDCl3) δ 2.46 (s, 3H), 3.85 (s, 3H), 4.01 (s, 3H), 6.51 (dd, J1=1.17 Hz, J2=3.13 Hz, 1 H), 7.06 (d, J=3.13 Hz, 1H), 7.36 (s, 1H), 7.69 (s, 1H); MS (ES, m/z): C13H13NO3: 232.19 (M++1).

Provenance & Evidence