H and C nuclear magnetic resonance (NMR) spectra were recorded at 400 MHz on a Bruker ARX-400 NMR spectrometer (Germany) with tetramethylsilane as internal standard. Column chromatography was performed using Merck (Germany) silica gel (230-400 mesh). Thin layer chromatography (TLC) was performed using Merck silica gel GF254, 0.25 mm thickness. For visualization, TLC plates were placed under aci...

[structure: see text]Derivatization with (+)- and (-)-chloromenthoxydiphenylsilane was used to determine the absolute configuration of the insect defensive agent pinoresinol (1). Although the (1)H NMR chemical shift differences of the resulting two diastereomers are small, (1)H NMR spectroscopy provided for the unambiguous assignment of the natural product's configuration. For this purpose, a n...

In this work, SO3H-functionalizedphthalimide (SFP) as a SO3H-containing solid acid is prepared by the reaction of phthalimide with chlorosulfonic acid, and characterized by FT-IR, 1H and 13C NMR, Mass, TG, DTG, XRD and SEM. Then, it is utilized as a highly efficient, heterogeneous and green catalyst for the one-pot multi-component condensation of dime...

Phytochemical constituents of Asparagus adscendens and Asparagus racemosus are being reported in the present communication. Two new sarsasapogenin glycosides have been isolated, one from each of the species. Structure elucidation of 1 and 10 has been accomplished through the extensive use of 1Dand 2D-NMR experiments including H-H (DQFCOSY), H-C (HMQC, HMBC) spectroscopy along with mass spectros...

A green and convenient protocol is described for the preparation of E-1-(alkylamino)-3- (1,3-dioxoisoindolin-2-yl)-2-methyl-1-oxopropan-2-yl viaone-pot three-component reaction between 2-(2-oxopropyl)isoindoline-1,3-dione, an alkyl isocyanide and an E-cinnamic acid in water at room temperature. The methods used to follow the reactions are TLC and NMR, which indicated that there is no side produ...

Background and objectives: The plants belonging to the genus Heliotropium L. (Boraginaceae) are the main sources of toxic pyrrolizidine alkaloids (PAs). In the present study, we have investigated the PAs of the aerial parts of Heliotropium transoxanum Bunge, a perennial species native to Iran. Methods: Silica gel column chromatography and silica gel PTLC were applied ...

Using a fast-injection system for dissolution dynamic nuclear polarisation, 1 H– H 2D NMR spectra tailored the analysis of mixtures are obtained in single-scan with enhanced sensitivity.

The reaction was carried out in dry EtOH under an argon atmosphere and at room temperature. NMR spectrum was recorded with a Bruker Avance 300 spectrometer and all chemical shifts are reported relative to the solvent signal [CDCl3: 7.26 ppm ( H)]. The assignments of the NMR signals were carried out under using 2D-NMR experiments H-HCOSY. IR spectra were recorded with a Thermo Nicolet NEXUS FTIR...

The H, C and H, C COSY NMR spectra of salicylohydroxamic acid (sha) were measured in DMSO-d6 solution. The B3LYP GIAO method with the 6-311þþG(d,p) basis set was chosen to reproduce the experimental spectra. All possible zusammen and entgegen conformers of monomeric sha were computed. After geometry optimisation (B3LYP/6311þþG(d,p)) only nine independent models of the molecule were shown to be ...

Semiochemicals are often produced in infinitesimally small quantities, so their isolation requires large amounts of starting material, not only requiring significant effort in sample preparation, but also resulting in a complex mixture of compounds from which the bioactive compound needs to be purified and identified. Often, compounds cannot be unambiguously identified by their mass spectra alo...