Dichloromethane → 5-Bromothiophene-2,3-dicarbaldehyde

Participants

Reaction Conditions

Reaction Steps

Bromine (1.2 mL, 7.5 mmol) was added drop wise to a solution of 2,3-thiophenedicarboxaldehyde (1.0 g, 7.1 mmol) in 20 mL of glacial acetic acid. The reaction mixture was stirred overnight at 70° C. and then excess bromine was quenched with a saturated solution of Na2S2O3. The organic layer was extracted with CH2Cl2, dried over Na2SO4 and volatiles were removed in vacuo to obtain a mixture of 1 and 4,5-dibromo-2,3-thiophenedicarboxaldehyde 2 as a brown solid (30:65 by 1H NMR spectroscopy). Spectroscopically pure compound was isolated by column chromatography using silica gel as stationary phase and a 4:1 mixture of CH2Cl2:hexanes. 1H NMR (500 MHz, CDCl3): δ 10.37 (s, 1H), 10.26 (s, 1H), 7.59 (s, 1H). 1H NMR data for 4,5-dibromo-2,3-thiophenedicarboxaldehyde (500 MHz, CDCl3): δ 9.81 (s, 1H), 7.36 (s, 1H).

Provenance & Evidence