5H-Cyclopenta[b]pyridine, 4-chloro-6,7-dihydro- synthesis

90685-58-8

54664-55-0

6,7-Dihydro-5H-cyclopenta[b]pyridine 1-oxide (2.5 g, 18 mmol) was mixed with phosphoryl chloride (20 mL, 200 mmol). The reaction mixture was stirred at 120 °C for 3 hours. Upon completion of the reaction, the excess POCl3 was removed by distillation under reduced pressure.The residue was diluted with 80 mL of EtOAc and neutralized to pH 7-8 with Na2CO3 solution.After filtration, the aqueous layer was extracted twice (40 mL each) with EtOAc. The organic extracts were combined, dried with anhydrous Na2SO4, filtered and concentrated under reduced pressure to give 4-chloro-6,7-dihydro-5H-cyclopenta[b]pyridine (2.6 g, 93% yield). LCMS analysis: calculated value of C8H9ClN(M + H)+: m/z = 154.2; measured value: 154.3.