Use of NMR Spectroscopy for Studying 2,4-Dioxo- and 4-Imino-2-oxo-3-phenyl-5-R-6-R′-thieno[2,3-d]pyrimidines

The study aims to investigate the structural features of 2,4-dioxo- and 4-imino-2-oxo-3-phenyl-5-R-6-R’-thieno[2,3-d]pyrimidines using nuclear magnetic resonance (NMR) spectroscopy. The compounds were synthesized by cyclization reactions under controlled conditions. NMR spectroscopy was employed to confirm molecular structures and analyze substitution effects on chemical shifts. The results demonstrated significant correlations between structural variations and spectral characteristics. These findings contribute to a deeper understanding of thienopyrimidine derivatives and their potential applications in medicinal chemistry. The research also highlights the reliability of NMR as a key method for structural elucidation of novel heterocyclic compounds.