7250-67-1

white to off-white crystals or crystalline powder

1-(2-Chloroethyl)pyrrolidine is a haloalkyl substituted pyrrolidine used in the preparation of various pharmaceutical compound such as the estrogen receptor antagonist Nafoxidine (N212800) and its ana logues.

The general procedure for the synthesis of N-(2-chloroethyl)pyrrolidine hydrochloride from tetrandrine and 2-chloroethanol was as follows: 165 mL (2 mol) of tetrandrine, 67 mL (1 mol) of 2-chloroethanol, and 200 mL of toluene were added sequentially to a reaction flask. The mixture was heated to reflux temperature and kept reacting for 3 hours. Upon completion of the reaction, the mixture was cooled to room temperature and the solid product was isolated. The solid was collected by diafiltration and the filter cake was washed with 20 mL of toluene. The temperature of the filtrate was controlled at about 75 °C and 200 mL of thionyl chloride was slowly added dropwise. After the dropwise addition was completed, the reaction was continued at reflux for 2 hours. At the end of the reaction, the mixture was cooled to room temperature and subsequently concentrated to dryness under reduced pressure. The resulting residue was recrystallized from anhydrous ethanol to give 105 g of white solid product in 62.3% yield. The melting point of the product was 198-203 °C.

Purify the hydrochloride by recrystallisation from isopropanol/di-isopropyl ether (charcoal) and recrystallise it twice more. The free base, b 55-56o/11mm, 60-63o/23mm and 90o/56mm, is relatively unstable and should be converted to the hydrochloride immediately, by dissolving in isopropanol and bubbling dry HCl through the solution at 0o, filtering off the hydrochloride and recrystallising it. The picrate has m 107.3-107.8o (from EtOH) [Cason J Org Chem 24 247 1959, Wright et al. J Am Chem Soc 70 3098 1948]. [Beilstein 20 III/IV 66.]

[1] Patent: US2013/85140, 2013, A1. Location in patent: Paragraph 0068; 0069
[2] Patent: CN104710394, 2017, B. Location in patent: Paragraph 0033-0035