3939-23-9

92-84-2

3939-23-9

In a 250 mL round-bottomed flask equipped with a magnetic stirrer and rubber septum, 10H-phenothiazine (7.97 g, 40.0 mmol) was dissolved in anhydrous tetrahydrofuran (60 mL) under nitrogen atmosphere. The dark-colored reaction solution was cooled to 0 °C (ice-water bath) by continuous nitrogen passage and degassed with a syringe for 10 min. Under nitrogen protection, N-bromosuccinimide (7.12 g, 40.0 mmol) was slowly added, followed by stirring the reaction mixture for 16 h and gradually warming it up to room temperature. Upon completion of the reaction, saturated aqueous sodium sulfite solution (150 mL) was added and the aqueous phase was extracted with dichloromethane several times. The organic layers were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. The residue was loaded on diatomaceous earth and purified by silica gel column chromatography (eluent: n-hexane/ethyl acetate, 20:1) to afford 3-bromo-10H-phenothiazine (4.95 g, 45% yield) as a colorless solid with an Rf-value (n-hexane/acetone, 4:1) = 0.33.1H NMR (CDCl3, 300 MHz) data were in agreement with the literature reports: δ 5.89 (s , broad peak, 1H), 6.52 (m, 1H), 6.61 (m, 1H), 6.83-7.15 (m, 5H).