Unequivocal determination of caulamidines A and B: application and validation of new tools in the structure elucidation tool box

Abstract

Newly described NMR experimental approaches can provide valuable structural details and a complementary means of structure verification.

Observation of untoward 3Jcc correlations in 1,1‐ADEQUATE spectra of pyrimidine analogs: Avoiding potential interpretation pitfalls

“…Over the past few years, our group has been involved in several internal projects and external collaborations that necessitated the acquisition of 1,1‐ADEQUATE spectra on different classes of small molecules ranging from natural products to synthetic molecular structures . The present study is a follow‐up to previous studies in which we have observed multiple‐bond correlations “leaking” into 1,1‐ADEQUATE spectra due to unusually large 2 J CC and 3 J CC couplings for particular structural motifs that can be nearly as large as some 1 J CC couplings .…”

Determination of Complex Small‐Molecule Structures Using Molecular Alignment Simulation

“…Subsequently, the PBLG structure was energyminimized and equilibrated in a chloroform box using the molecular simulation software GROMACS. [13] P3D was evaluated on the basis of RDCs measured for six small molecules dissolved in chloroform and weakly aligned by PBLG: the fungicidal cyclopentenone 4,6-diacetylhygrophorone A (DAHPA), [14] isopinocampheol (IPC), [12a] the alkaloids strychnine and caulamidine, [15] [16] and the lactone parthenolide. [12b] The six small molecules have different numbers of (relative) stereoisomers, ranging from 4 for DAHPA to 16 for parthenolide (see Figures S1-S6 in the Supporting Information).…”

Chemical shift assignment of mono‐ and di‐bromo triimidazo[1,2‐a:1′,2′‐c:1″,2″‐e][1,3,5]triazine derivatives by DFT/NMR integrated approach

“…In the last few years, the application of quantum mechanical (QM) predictions has been gaining a considerable attention by the scientific community for high accuracy in the reproduction of the experimental NMR properties even at low levels of theory and thanks to the increasing computational power. This hybrid approach has been demonstrated as a valuable method for the structural studies of organic compounds, spanning from configurational and conformational assignments to structure elucidation of natural products. The use of QM‐NMR integrated strategy is not limited to stereostructural studies but could support the total synthesis of natural compounds and also the analysis of ligand–macromolecule interactions.…”