Synthesis and Crystal Structure of Thiazolopyrimidine Derivatives: Insights into Weak Interactions

Thiazolo[3,2-a]pyrimidines namely ethyl 2-acetyl-5-(2-fluorophenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 3a, ethyl 2-acetyl-5-(3-fluorophenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 3b, and ethyl 2-acetyl-5-(4-fluorophenyl)-3,7-dimethyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylate 3c were obtained by one pot synthesis using substituted 3,4 dihydropyrimidine2-thione (1a–1c) and 3-chloro-2,4-pentanedione in ethanol and characterized by single-crystal X-ray diffraction. The variation in the position of fluorine atom on pyrimidine nucleus and insight into the self-assembly of compounds with varied types of non-covalent interactions has great influence on crystal packing.