Two-Stage Synthesis of 3-(4-Hydroxyphenyl)-1′,3′,6-trimethyl-2′H,3H,4H-spiro[furo[3,2-c]pyran-2,5′-pyrimidine]-2′,4,4′,6′(1′H,3′H)-tetraone

Spirocyclic compounds are experiencing a research surge due to their unique 3D structure, offering enhanced pharmacological, industrial, and material applications. They are increasingly used in medicinal chemistry to improve drug-like properties, such as solubility and target binding, and are also being utilized for advanced material applications, including electronics and photonics. In this communication, 3-(4-hydroxyphenyl)-1′,3′,6-trimethyl-2′H,3H,4H-spiro[furo[3,2-c]pyran-2,5′-pyrimidine]-2′,4,4′,6′(1′H,3′H)-tetraone was prepared via a two-stage transformation including a tandem Knoevenagel–Michael reaction and NBS-induced cyclization. At the first stage, a previously unknown ionic scaffold, morpholin-4-ium 5-((4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)(4-hydroxyphenyl)methyl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate was also isolated. Structures of the newly synthesized compounds were established by 1H and 13C NMR, IR spectroscopy, high-resolution mass spectrometry, and elemental analysis.