Supramolecular interactions in X-ray structures of oxalamides: Green synthesis and characterization

• Published in: Journal of molecular structure 2022-09, Vol.1263, p.133144, Article 133144
• Main Authors: Molina-Paredes, Areli A., Lara-Cerón, Jesús A., Ibarra-Rodríguez, Marisol, del Angel-Mosqueda, Casiano, Dias, H.V. Rasika, Jiménez-Pérez, Víctor M., Muñoz-Flores, Blanca M.
• Format: Article
• Language: English
• Subjects: Green synthesis; Oxalamides; Supramolecular interactions; X-ray diffraction
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2022.133144

•Solvent-free synthesis of five symmetric oxalamides.•The molecular structure of oxalamide 1 reveals that amide hydrogen presents a trifurcated character.•The crystal structure of lithium complex 7 shows CH/π stacking between the aromatic rings and THF molecules. Nowadays one of the biggest challenges of chemists all over the world is to design eco-friendly synthesis with a high atom economy and low E-factor. Solvent-free reactions are one of the best ways to avoid waste. Here we report a short series of solvent-free synthesis of five oxalamides which were carried out between oxalyl chloride and the corresponding primary amines (2-fluoroaniline (1), 2,6-diisopropylaniline (2), 2,6-dimethylaniline (3), (1R)-1-phenylethanamine (4), and cis-myrtanylamine (5) in ice bath; the release of HCl was neutralized by a saturated NaOH solution. All oxalamides 1-5 were afforded in good yields with high purity. NMR and single-crystal X-ray diffraction results revealed the characteristic intermolecular and intramolecular interactions of N,N'-oxalamides across the amide core. Notably, the X-ray structure of 1 reveals that amide hydrogen presents a trifurcated character due to the intra and intermolecular hydrogen interactions. Additionally, the crystal structure of lithium complex 7 shows CH/π stacking between the aromatic rings and tetrahydrofuran molecules. [Display omitted]