Synthesis, Spectroscopic Properties and DFT Calculation of Novel Pyrrolo[1 ′ ,5 ′ -a]-1,8-naphthyridine Derivatives through a Facile One-pot Process

Novel pyrrolo[1 ′ ,5 ′ -a]-1,8-naphthyridine compounds ( L1 - L4) have been synthesized through a facile one-pot process by the reaction of the corresponding 1,8-naphthyridines with aliphatic anhydride. The structures were established by spectroscopic data. Further, X-ray crystal analysis of 7-diacetamino-2,4-dimethy-1,8-naphthyridine ( L1 ) identifies its molecular structure and reveals π - π stacking. The synthetic mechanisms for L2 , L3 were studied by density functional theory calculations. And a comprehensive study of spectroscopic properties involving experimental data and theoretical studies is presented. L1 exhibited electronic absorption spectrum with λ max at ∼320 nm. L2 - L4 exhibited similar electronic absorption spectra with λ max at ∼390 nm that is tentatively assigned to π → π * transition. The assignment was further supported by density functional theory (DFT) calculations. Graphical Abstract Novel pyrrolo[1′,5′-a]-1,8-naphthyridine compounds have been synthesized through a facile one-pot process. Further, X-ray crystal analysis and spectroscopic properties are presented.