Acetic Acid → Dimethyl indole-2,3-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of aniline (3.91 ml, 43.0 mmol) and dimethyl but-2-ynedioate (5.28 ml, 43.0 mmol) in N,N-dimethylacetamide (DMA) (194 ml)/acetic acid (64.8 ml) was degassed with O2 for 5 min and treated with Pd(OAc)2 (0.964 g, 4.30 mmol). The reaction mixture was heated to 115° C. and placed under and atmosphere of O2. After 18 h, the reaction was cooled to ambient temperature, filtered through a pad of Celite™, diluted with EtOAc and washed with H2O. The organic was washed with brine, dried (MgSO4), filtered and concentrated. The residue was purified by ISCO (0-50% EtOAc-hexanes: 220 g SiO2) to afford dimethyl 1H-indole-2,3-dicarboxylate (5.5 g, 23.58 mmol, 54.9% yield) as a yellow solid: 1H NMR (400 MHz, CHLOROFORM-d) δ=9.32 (br. s., 1 H), 8.08 (d, J=8.2 Hz, 1 H), 7.48-7.44 (m, 1 H), 7.42-7.37 (m, 1 H), 7.29 (s, 1 H), 4.01 (d, J=2.0 Hz, 6 H); LCMS (m/z) ES+=234 (M+1).

Provenance & Evidence