Microwave Irradiation Syntheses and Crystal Structures of Two Series of Novel Fivemembered Heterocyclic Mono-Imine Compounds

• Published in: Current organic synthesis Vol. 16; no. 3; p. 444
• Main Authors: Su, Biyun, Li, Yaning, Pan, Dandan, Faida, Paison, Yan, Tingyu, Qu, Zhan
• Format: Journal Article
• Language: English
• Published: United Arab Emirates 2019
• Subjects: Schiff base condensation; heterocyclic ligands; Mono-imine compounds; microwave irradiation; aromatic amines; crystal structures
• ISSN: 1570-1794
• DOI: 10.2174/1570179416666181207125604

The late transition metal complexes with five-membered heterocyclic mono-imine ligands have attracted much attention because of their potential application in olefin polymerization catalysis. In order to increase the coordination ability of heteroatom N and S to center metals, CH3 group was introduced into the side arm of pyrrole imine and thiophene imine respectively, to get two series of novel five-membered heterocyclic imine compounds, mono(imino)pyrroles and mono(imino)thiophenes. Two series of novel five-membered heterocyclic compounds with the mono-imine group were synthesized from the p-toluene sulfonic acid catalyzed Schiff base condensation of aromatic amines and 2-acetylpyrrole/ 2-acetylthiophene respectively, using CH3 group to substitute the common H atom on the side arm of pyrrole imine/ thiophene imine. All the heterocyclic mono-imine compounds were characterized adequately by means of 1H NMR, 13C NMR, FT-IR, elementary analysis, as well as X-ray crystallographic diffraction. The reactivity differences between two precursor 2-acetylpyrrole and 2-acetylthiophene with aromatic amines were compared and discussed in detail. Compared to traditional heating methods, the solvent-free microwave irradiation seemed more efficient to prepare these series of five-membered heterocyclic mono-imine compounds, which resulted in a higher yield and cleaner product.