Potassium Carbonate → Niguldipine hydrochloride, (+/-)-

Participants

Reaction Steps

A mixture of 13 g of 3-methyl 5-(3-bromopropyl) (+)-1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-pyridine-3,5-dicarboxylate, 7.85 g of 4,4-diphenylpiperidine hydrochloride and 12 g of potassium carbonate in 120 ml of toluene and 25 ml of water is refluxed for 14 h under a nitrogen atmosphere and with vigorous stirring. After cooling, the phases are separated; the organic phase is washed twice with water, dried over sodium sulphate and evaporated in vacuo. The oily residue is dissolved in 140 ml of dioxane, after which 2.3 ml of concentrated hydrochloric acid solution (12.5 M, d=1.19) are added and 20-25 ml of the solvent mixture are then distilled off in vacuo. On standing at room temperature, the product crystallises spontaneously or after trituration and is filtered off under suction after 16 h, washed with dioxane and diisopropyl ether and dried in vacuo at 80° C. 16 g of the title compound of m.p. 158°-160° C. and [α]22D =+14.4° (c=1, methanol) are obtained.

Provenance & Evidence