Dimethylformamide → 5-Chloro-1-(4-fluorophenyl)indol-3-carbaldehyde

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Reaction Steps

Phosphorus oxychloride (12.5 g, 0.081 mol) was added to N,N-dimethylformamide (29.5 g, 0.19 mol) at 0°-5° C. After stirring for 10 minutes a solution of 5-chloro-1-(4-fluorophenyl)indole (20 g, 0.081 mol) in N,N-dimethylformamide (50 mL) was added at 0°-5° C. The reaction mixture was stirred for 0.5 h and subsequently poured into ice. The resulting mixture was made alkaline with concentrated NaOH and after stirring for 1 h at room temperature the mixture was extracted with diethyl ether (2×250 mL). The combined organic phases were dried (Na2SO4),the solvents evaporated and the remaining oil was purified by column chromatography (eluted with ethyl acetate/heptane 1:1) affording pure title compound 20.1 g (90%) which crystalized from heptane: mp 152°-154° C.; 1H NMR (CDCl3) δ 7.20-7.35 (m, 4 H), 7.50 (dd, 2 H), 7.85 (s, 1 H), 8.35 (s, 1 H), 10.05 (s, 1 H). Anal. (C15H9NO) C, H, N.

Provenance & Evidence