Dimethylformamide → 2-(4-chloro-phenyl)-3-formyl-1H-indole-4-carboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

Phosphorous oxychloride (0.42 g, 2.71 mmol) was added to DMF (0.99 g, 13.57 mmol) at 0° C. The resulting colorless solution was added dropwise to a solution of 2-(4-chloro-phenyl)-1H-indole-4-carboxylic acid methyl ester (0.52 g, 1.81 mmol) in 10 mL dry CH2Cl2 at 0° C. The reaction was stirred at 0° C. for 10 min then quenched by addition of 5 mL 2 M NaOAc(aq). The layers were separated and the aqueous layer extracted once with CH2Cl2. The combined organic layers were dried (MgSO4) then concentrated in vacuo leaving anorange oil which crystallized on standing. The crystals were rinsed with CH2Cl2 then dried in vacuo to yield 2-(4-chloro-phenyl)-3-formyl-1H-indole-4-carboxylic acid methyl ester, 231 mg (41%) as an off-white solid: m.p. 221-222° C.; 1H NMR (300 MHz, d6-DMSO) δ 3.93 (s, 3H), 7.49 (app t, J=7.5 Hz, 1H), 7.71 (m, 4H), 7.94 (d, J=7.8 Hz, 2H), 9.71 (s, 1H), 13.67 (br s, 1H). MS (electrospray, [M−H]) 312.

Provenance & Evidence