4-Hydroxybenzaldehyde → Methyl 1-(4-hydroxybenzyl)-1,2,5,6-tetrahydropyridine-3-carboxylate hydrochloride

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Reaction Conditions

Reaction Steps

4-Hydroxybenzaldehyde (1.34 g.) and sodium cyanoborohydride (0.7 g.) were added to a solution of methyl 1,2,5,6-tetrahydropyridine-3-carboxylate hydrochloride (3.1 g.) in methanol (30 ml.). The mixture was stirred for 3 days at 25° C., evaporated and water (30 ml.) added to the residue followed by concentrated hydrochloric acid to pH 1. This mixture was extracted with ether (2×20 ml.) and the extracts discarded. The aqueous phase was basified to pH 9 with 10% w/v sodium carbonate solution and then extracted with ether (2×30 ml.). The combined extracts were dried (MgSO4) and evaporated. The oil obtained was dissolved in acetone and treated with a slight excess of ethereal hydrogen chloride. The solid which was precipitated was collected by filtration to give methyl 1-(4-hydroxybenzyl)-1,2,5,6-tetrahydropyridine-3-carboxylate hydrochloride (2.05 g.). A portion was recrystallised from methanol and acetone to give pure material of m.p. 212°-214° C. (dec.).

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