1-Acetylpiperidine → 2-(3,5-Dibromo-2-isopropoxyphenyl)-5-[1-(1-piperidinyl)-ethyl]-1H-pyrrole hydrochloride hemihydrate

Beteiligte Stoffe

Reaktionsschritte

To 1-acetylpiperidine (0.36 ml) under argon was added phosphorous oxychloride (0.26 ml) at room temperature. The mixture was stirred at room temperature for 50 minutes and 1,2-dichloroethane (5 ml) was added. The solution was cooled to 5° C. and 2-(3,5-dibromo-2-isopropoxyphenyl)-1H-pyrrole (D7) (0.52 g) in 1,2-dichloroethane (5 ml) was added in one portion. The mixture was stirred at 5°-10° C. for 20 minutes and was then stirred at room temperature for 22 hrs. The mixture was cooled in an ice bath and sodium borohydride (0.50 g) was added in one portion. After stirring for a further 2 hrs, water (7.2 ml) was added dropwise over 6 minutes. After a further 4 minutes, MeOH (6 ml) was added over 6 minutes. After stirring for a further 10 minutes, the mixture was partitioned between water (100 ml) and dichloromethane (50 ml). The aqueous layer was re-extracted with dichloromethane (2×40 ml) and the combined organic layers were dried over sodium sulphate. The residue was dissolved in MeOH (7 ml), dichloromethane (8 ml) and hydrochloric acid (35%; 2 ml) and was stirred at room temperature for 3 hrs. The mixture was partitioned between dichloromethane (100 ml) and water (60 ml). The aqueous layer was brought to pH 12 with 10% NaOH and was extracted with dichloromethane (2×40 ml). The combined organic layers were dried over sodium sulphate and the solvent was removed in vacuo. The residue was chromatographed on neutral alumina to give the free base of the title compound. This material was dissolved in diethyl ether (100 ml) and was washed with water and was extracted with 0.4M HCl (4×25ml). The combined HCl layers were extracted with dichloromethane (4×50 ml). The ether layer was then diluted with pentane and re-extracted with the HCl layer. The acid layer was extracted with dichloromethane and the combined dichloromethane extracts were dried over sodium sulphate and evaporated in vacuo to give the title compound (E20).

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