4-Hydroxybenzaldehyde → 1-(4-Hydroxybenzyl)-1,2,3,6-tetrahydropyridine

Participants

Reaction Steps

A mixture of 4-hydroxybenzaldehyde (6.1 g.) and 1,2,3,6-tetrahydropyridine (8.3 g.) in methanol (70 ml.) was adjusted to pH7 by addition of ethereal hydrogen chloride. Sodium cyanoborohydride (3.15 g.) was then added in portions to the stirred solution at 25° C. The mixture was stirred at 20°-25° C. for four days, evaporated, and water (100 ml.) added to the resultant residue. The mixture obtained was adjusted to pH2 with dilute hydrochloric acid and extracted with ether (2×50 ml.). The extracts were discarded. The aqueous phase was separated and adjusted to pH9 with 10% w/v sodium carbonate solution, to give crude 1-(4-hydroxybenzyl)-1,2,3,6-tetrahydropyridine as a solid. This solid was dissolved in acetone (100 ml.) and the solution acidified to pH2 with ethereal hydrogen chloride to give 1-(4-hydroxybenzyl)-1,2,3,6-tetrahydropyridine hydrochloride (6.7 g.), m.p. 234°-236° C. (after recrystallisation from methanol/ethyl acetate.)

Provenance & Evidence