Diisopropylethylamine → 1-(Chroman-3-ylmethyl)-1,2,5,6-tetrahydropyridine-3-carboxylic acid methyl ester

Participants

Reaction Steps

First 5.55 g (25 mmol) of 1,2,5,6-tetrahydropyridine-3-carboxylic acid methyl ester hydrobromide (guvacoline hydrobromide) and then 11.31 g (87.5 mmol) of N-ethyl-N,N-diisopropylamine are added to a solution of 7.96 g (25 mmol) of 3-(p-toluenesulphonyloxymethyl)chroman in 100 ml of dimethylformamide. The mixture is stirred for 15 hours at 50° and then concentrated by evaporation under a high vacuum. Water is added to the residue and extraction is carried out with diethyl ether. The organic phases are washed with water and extracted with 2N hydrochloric acid. The hydrochloric acid extracts are combined, rendered alkaline, while cold, with sodium hydroxide solution (30% strength) and extracted with dichloromethane. The combined organic phases are dried over sodium sulphate and concentrated by evaporation in vacuo. 5.92 g (83%) of 1-(chroman-3-ylmethyl)-1,2,5,6-tetrahydropyridine-3-carboxylic acid methyl ester are obtained in the form of a pale yellow oil. The 1-(chroman-3-ylmethyl)-1,2,5,6-tetrahydropyridine-3-carboxylic acid methyl ester hydrochloride produced therefrom using hydrochloric acid in diethyl ether melts at 158°-159° after crystallisation from methanol/diethyl ether.

Provenance & Evidence