Publication details
Amlodipine Benzenesulfonate: A Mechanistic Investigation of Its Industrial Preparation via Detritylation of N-tritylamlodipine and Related NMR Studies
| Authors | |
|---|---|
| Year of publication | 2009 |
| Type | Article in Periodical |
| Magazine / Source | CROATICA CHEMICA ACTA |
| MU Faculty or unit | |
| Citation | |
| web | https://hrcak.srce.hr/38639 |
| Keywords | kinetics; detritylation; mechanism; acid-catalysed deaminations |
| Description | Kinetics and product analysis of detritylation of N-tritylamlodipine by benzenesulfonic acid in methanol, methanol-chloroform (volume ratio 9:1), ethanol, 2-propanol, and methanol/2-propanol (mole ratio 1:1) have been investigated by HPLC; amongst these reaction conditions are ones closely similar to those of one method of manufacturing amlodipine benzenesulfonate. Kinetics of detritylation of N-tritylamlodipine have also been investigated in methanol-d(4) by (1)H NMR spectroscopy and the agreement with the results by HPLC is good. The rate of detritylation increases with increasing concentrations of benzenesulfonic acid, and p-methoxy-substituents in the trityl group have been shown to lead to faster reactions. In methanol, the rate is hardly affected by 10 % (vol. fraction) chloroform. These studies relate to mechanistic investigations of acid-catalysed deaminations of methoxy-substituted tritylalkylamines, and Arrhenius activation parameters (E(a) and A) are similar indicating a common generic mechanism. Acid-catalysed traps-esterification has been shown by HPLC to accompany detritylation in methanol, and attendant protium-deuterium exchange in the methyl at C6 by reversible acid-catalysed iminium ion formation in the 4-aryl-1,4-dihydropyridine moiety of both N-tritylamlodipine and amlodipine has been investigated in deuteriated methanol by (1)H, (13)C, and (15)N NMR spectroscopy. |