an efficient synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles by one-step condensation of  an aldehyde, benzil, ammonium acetate and primary amine in the presence of nanocrystalline magnesium aluminate under microwave irradiation is described. the advantages of this catalyst are including simple work-up, low cost and reusability. compared with conventional methods, the ...

On the basis of spectroscopic investigations (1H-NMR, 13C-NMR, UV, IR and MS spectroscopy), elemental analysis and degradation reactions the structure of a new alkaloid discarine G from the bark extract of Discaria febrifuga Mart. is elucidated.

1H and 13C NMR spectra of eleven 2-phenacylbenzoxazoles (ketimine form) show that their CDCl(3)-solutions contains also (Z)-2-(benzo[d]oxazol-2-yl)-1-phenylethenols (enolimine form). Intramolecular hydrogen bonding in the latter tautomer was found to be significantly weaker than that one in respective (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines. Integrals of the 1H NMR signals were used to evaluat...

We demonstrate the use of Lee-Goldburg cross-polarization (LG-CP) NMR under fast magic-angle spinning (MAS) to investigate the amplitude and geometry of segmental motions in biomolecular and polymeric solids. Motional geometry information was previously available only from 2H NMR, which, however, has limited site resolution and requires site-specific isotopic labeling. Using a 2D LG-CP techniqu...

Understanding the molecular interactions between inorganic phases such as silica and organic material is fundamental for chromatographic applications, for tailoring silica-enzyme interactions, and for elucidating the mechanisms of biomineralization. The formation, structure, and properties of the organic/inorganic interface is crucial in this context. Here, we investigate the interaction of sel...

Indirect detection of 13C and 15N nuclear magnetic resonance (NMR) spectra through 1H NMR signals offers large sensitivity advantages in studies of organic and biological molecules in solution and is almost universally employed.1-3 Although sensitivity enhancement by indirect detection was first demonstrated in NMR4-6 and nuclear quadrupole resonance7,8 of solids, direct detection has generally...

From methanolic extract of aerial parts of Peucedanum ruthenicum M. Bieb (Apiaceae) collected from Mazandaran province of Iran, four flavonoids namely Isorhamnetin 3-0-rutinoside 1, rutin 2, quercetin 3, morin 4 and two phenolic acids namely caffeic acid 5 and p-coumaric acid 6 have been isolated by Paper Chromatography (PC) and crystallization. Their structures were elucidated by MS, 1H, 13C N...

Introduction: Cannabidiol (CBD) has become a promising bioactive for the next decades after recent recognition of medical potential Cannabis derivatives by United Nations member countries, as it no psychotropic your isomer ∆9-tetrahydrocannabinol (∆9-THC). The differentiation these isomers been studied decades. Recent studies demonstrate that even with more subtle chemical characteristics, such...