Understanding 2-(Nitromethylene)hexahydropyrimidin-5-ol Reaction Processes and NMR Spectroscopy: A Theoretical and Experimental Investigation

Ketene dithioacetals have significant applications in various fields, including natural products, pharmaceuticals, agrochemicals, and corrosion inhibitors. These compounds are highly valued for their reactivity and ability to participate in a wide range of organic syntheses. In this context, the reaction between 1,3-diaminopropan-2-ol and 1,1-bismethylsulfanyl-2-nitroethylene has been studied experimentally and theoretically by using density functional theory (DFT) calculations. A theoretical mechanism of formation of two possible products, 2-(nitromethylene)hexahydropyrimidin-5-ol (with a six-membered heterocycle) and (2-(nitromethylene)oxazolidin-5-yl)methanamine (with a five-membered heterocycle), is for the first time predicted. The present DFT results indicate that both mechanisms are exothermic, with energy barriers approximately 20 kcal/mol higher than those of the reactants. Among the two, the formation of 2-(nitromethylene)hexahydropyrimidin-5-ol is energetically more favorable. This compound was synthesized and analyzed by different experimental techniques (IR, nuclear magnetic resonance (NMR), and high-resolution mass spectrometry). The 1H and 13C NMR chemical shifts of 2-(nitromethylene)hexahydropyrimidin-5-ol were calculated using the GIAO/B3LYP, showing good agreement with our experimental observations. These findings highlight an important match between experimental results and theoretical predictions, offering deeper insights into ketene dithioacetal reactions. The new data and contributions are expected to generate significant interest in future applications.

Structural and optical profile of a multifunctionalized 2-pyridone derivative in a crystal engineering perspective

The supramolecular structural features of organic molecules are very important with regard to their widespread properties in both solids and solutions. Herein, we describe the synthesis of a novel multifunctional 2-pyridone derivative, namely 6-(4-chlorophenyl)-5-formyl-4-methylsulfanyl-2-oxo-1,2-dihydropyridine-3-carbonitrile, C₁₄H₉ClN₂O₂S, denoted P1, and its structural features were established through X-ray crystallography. A Hirshfeld surface analysis followed by a two-dimensional fingerprint plot analysis was carried out. A frontier molecular orbital investigation and natural bond orbital (NBO) calculations explored the charge-transfer interactions associated with the molecular system. The optical properties of the 2-pyridone derivative were elucidated through UV-Vis absorption and emission spectroscopy, indicating a strong blue emissive nature with a colour purity of 82.5%, a short-lived lifetime and a large Stokes shift. Time-dependent density functional theory (TD-DFT) was used to gain some insight into the absorption behaviour and emissive characteristics of P1.