Synthesis and crystal structure analysis of two thiazolo[3,2-a]pyrimidine derivatives

Abstract

UDC 548.737Synthesis of 5R*-(3-methoxy-phenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarboxylic acid diethyl ester (2a) and 3,7-dimethyl-5S*-thiophen-2-yl-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarboxylic acid diethyl ester (2b) are achieved by the cyclocondensation of 3,4-dihydropyrimidine-2-thione derivative with α-haloester. Preliminary analysis was done spectroscopically by means of 1 H NMR spectra, mass spectra and elemental analyses. Further the structures were confirmed by X-ray crystal structure analysis. The two molecules are not identical in configuration. In both the compounds the central pyrimidine ring adopts a conformation which is best described as an intermediate between a boat and screw boat form. The crystal structure is stabilized by intermolecular C-H…O and C-H…π weak interactions.