Synthesis, crystal structure and DFT calculations of novel 2-substituted-1H-perimidines

Perimidines or 1H-perimidines represent an important class of heterocyclic compounds built up of a dihydropyrimidine ring peri-fused to a naphthalene moiety. In the past decades efficient synthetic methods for the preparation of perimidines are in focus of research [1, 2] as well as their targeted functionalizations to give rise to new multicomponent systems with interesting pharmaceutical properties: antifungal, antiulcer, antitumor or antimicrobial [3, 4]. Here we report synthesis of four 2-substituted perimidine derivatives. IR and NMR spectroscopic results, single-crystal X-ray structure analysis ((1H-perimidine-2-yl)-methanol) and powder X-ray structure analysis (2-cyanomethyl-perimidine) as well as DFT calculations are also reported. Perimidines exhibit 1, 3-annular tautomerism due to two possible hydrogen positions at one or the other endocyclic nitrogen atoms or both resulting in the imine or enamine forms.