反应详情

温度

70 °C

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).

1. customexcess bromine was quenched with a saturated solution of Na2S2O3
2. extractionThe organic layer was extracted with CH2Cl2
3. dry with materialdried over Na2SO4 and volatiles
4. customwere removed in vacuo
5. customto obtain
6. customSpectroscopically pure compound was isolated by column chromatography