Synthesis of 1,4-dihydropyridines having an N-alkylpyridinium substituent at the 4-position and their affinity towards liposomal membranes

Effect of the solvent nature on the course of quaternization of 3,5-diethoxycarbonyl-2,6-dimethyl-4-(3-pyridyl)-1,4-dihydropyridine

“…When using acetonitrile, the solvent was evaporated after cooling, the residue was recrystallized from acetone, and dried. [22]). The UV spectrum and the 1 H NMR spectrum corresponded completely with those published previously in [22].…”

“…However, as a result of the effect of solubility of pyridinium bromides 2a-d and the starting material 1 in acetone, 2-butanone, and acetonitrile, the yield of the obtained products may vary insignificantly. The nature of the alkylating agent affects the quaternization reaction rate and the yield of products [22]. Investigation of this factor is not the purpose of this work, since changes in the nature of the alkylating agents were inadequate for clarification of this dependence.…”

“…This is indicated by the reduction in reaction time, higher yield (Table 1), and purity of the corresponding products 2a-d. Compounds 2c,d were synthesized previously [22] by boiling a mixture of compound 1 with the appropriate alkyl halide, but taken in excess, in acetone (yields were 60-63%). However, as a result of the effect of solubility of pyridinium bromides 2a-d and the starting material 1 in acetone, 2-butanone, and acetonitrile, the yield of the obtained products may vary insignificantly.…”

“…An excess of alkyl halide was used in [22] to reduce the reaction time, but this hinders the isolation and purification of products.…”

“…derivatives [23], that lengthening the carbon chain of the alkyl halide increases the quaternization reaction time [22]. An excess of alkyl halide was used in [22] to reduce the reaction time, but this hinders the isolation and purification of products.…”