Synthesis and crystal structure of two nitro-regioisomers of cis-4(4- methoxyphenyl)-3-methyl-2-phenyl-1,2,3,4-tetrahydroquinoline

Abstract

Here we synthesized two nitro regioisomers of cis-4-(4-methoxyphenyl)-3-methyl-2-phenyl-l,2,3,4-tetrahydroquinoline via the "one pot" three-component imino Diels-Alder reaction catalyzed by BF3.OEt2 and completed its structural characterization using the single crystal X-ray diffraction technique and other spectroscopic methods. To monitor the purity of the products and the composition of the reaction mixtures we used thin layer chromatography, and isolated and purified the products by column chromatography. Then using nuclear magnetic resonance (NMR) and mass spectrometry (MS) identified the substances. We collected X-ray diffraction data for crystal characterization by using a Bruker AFC7S Mercury diffractometer with Mo-Ka radiation (λ = 0.71073Â) at room temperature. The structures of these regioisomers were confirmed by 1H NMR and 13C NMR studies and studied their crystal structure using single crystal X-ray diffraction technique. The spectroscopy analyses (NMR, GC-MS and X-ray diffraction) provided a complete characterization and enabled the correct stereochemistry for the tetrahydroquinoline ring. We determined the molecular packing for the 5-nitro regioisomer 4 is the product of the combination of intermolecular hydrogen bonds and van der Waals interactions, while for 7-nitro regioisomer 3 is mainly due to weak intermolecular van der Waals interactions and N-H φ.