2-chloro-6,7-dihydro-5H-cyclopenta[b]pyridine

115122-63-9

117890-55-8

The general procedure for the synthesis of 2-chloro-6,7-dihydro-5H-2,3-cyclopentenopyridine from 2-hydroxy-6,7-dihydro-5H-cyclopenta[b]pyridine-3-carboxylic acid is as follows: 20 kg of 2-hydroxy-6,7-dihydro-5H-cyclopenta[b]pyridine-3-carboxylic acid and 200 kg of a 20% hydrochloric acid solution were added to a reactor and the reaction was carried out at reflux. Upon completion of the reaction, the reaction solution was concentrated to 2250 kg to remove excess hydrochloric acid and subsequently crystallized naturally. During the crystallization process, it was necessary to ensure that no hydrogen chloride gas escaped, resulting in 14 kg of 2-chloro-6,7-dihydro-5H-2,3-cyclopentenopyridine.