Synthesis and physical-chemical properties of functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid

Abstract

Introduction. Synthetic research of new biologically active compounds occupies an important place in modern pharmaceutical science.Thus it is important to develop techniques for the biologically active substances functionalization. Esters and amides take special place among the variety of functional derivatives of organic acids,. These fragments are well-known pharmacophores and could be found in a wide range of drugs. Thus, the nootropic agent pyracetam is 2-oxo-1-pyrolidineacetamide, and is the selective antagonist of β-adrenoreceptores; atenolol is a derivative of benzeneacetamide. Substituted acetamide and ester fragments are also present in the structures of aprofen, spasmolitin, acetylidine and β-lactam cephalosporins and penicillins antibiotics.Aim of our research was the synthetic method development for functional derivatives of 3-benzyl-8-propylxanthinyl-7-acetic acid and the study of their physical-chemical properties.

Materials and methods. Melting points were determined using capillary method on DMP (M). ¹Н NMR-spectra were recorded by Varian Mercury VX-200 device (company «Varian» – USA) solvent – (DMSO-d6), internal standard – ТМS. Elemental analysis of obtained compounds was produced on device Elementar Vario L cube. Chemical shifts were reported in ppm (parts per million) values. Infrared (IR) spectra were measured on a Bruker Alpha instrument using a potassium bromide (KBr) disk, scanning from 400 to 4000 cm^-1.

Results and discussion. We selected 3-benzyl-8-propylxanthinyl-7-acetic acid as initial compound for our study. For synthesis of hexyl, heptyl, octyl, nonyl, decyl and benzyl esters of 3-benzyl-8-propylxanthinyl-7-acetic acid we used alternative method, that included alkylation of sodium salts of acids with alkyl halogens. Reaction was made at DMF medium by reflux of reagents. Next stage of our research was the synthesis of amides of 3-beznyl-8-propylxanthinyl-7-acetic acid by the reaction of ethyl or propyl esters with butylamine, benzylamine, p-methylbenzylamine or p-fluorobenzylamine. It should be noted that we conducted reaction without solvent in the medium of amine and reagents were not reflux but heated at 80 ^оС. The structures of all obtained compounds were proved by the elemental analysis, IR- and ¹H NMR-spectroscopy.

Conclusions. Obtained results of our work can be used for further search of biological active compounds among functional derivatives of xanthinyl-7-alkanyl acids