Absolute configurations of talaromycones A and B, α-diversonolic ester, and aspergillusone B from endophytic Talaromyces sp. ECN211

• Ken-ichi Nakashima,
• Junko Tomida,
• Takao Hirai,
• Yoshiaki Kawamura and
• Makoto Inoue

Beilstein J. Org. Chem. 2020, 16, 290–296, doi:10.3762/bjoc.16.28

• determination of the absolute configuration of 1–4 by single-crystal X-ray diffraction and ECD spectroscopy. In addition, we also updated the crystallographic data for glauconic acid (5), a known nonadride. Results and Discussion Talaromyces sp. ECN211 was isolated from healthy leaves of Selaginella tamariscana

• derivatives, α-diversonolic ester (3) and aspergillusone B (4), from the cultures of Talaromyces sp. ECN211. The absolute configurations of 3 and 4 had previously only been assigned tentatively and could now be confirmed by single-crystal X-ray diffractometry and ECD spectroscopy. We also revealed the

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

• extent of secondary chiral organization, thus also allowing a monitoring by ECD spectroscopy [16][17]. The non-degenerate coupled oscillator mechanism is also responsible for generating ECD signals in correspondence with electronic transitions of achiral chromophores surrounded by a chiral environment

• ligand as a function of concentration and/or mixing ratios [3][5][6][9][18]. However, ECD relies on the difference in absorption between left and right circularly polarized light which makes it at least two orders of magnitude less sensitive than absorption spectroscopy [1][9]. ECD spectroscopy can give

• binding geometry, as will be discussed below. ECD spectroscopy shows several advantages for investigating DNA, RNA and their complexes with ligands with respect to other spectroscopic techniques (non-polarized spectroscopies, NMR, X-ray single crystal diffraction) [6][9]: The experiments are technically

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• and comparison of the data with DFT calculations, while ECD spectroscopy was found to be inconclusive in this case. The enantiomeric purity of samples from test purchases and police seizures was assessed by a self-developed chiral HPLC method. Keywords: chiral HPLC; ECD spectroscopy; NPS; synthetic

• CO and/or a cyclohexyl radical or methylenecyclohexane. As MDMB-CHMCZCA bears a stereogenic center at C-1', the elucidation of the absolute configuration of the sample was attempted by ECD spectroscopy. While the UV spectra can be adequately predicted by TD-DFT calculations (time-dependent density

• ) by VCD spectroscopy and comparison with DFT calculations. Thus, the readily available (S)-tert-leucine would be a starting material for the synthesis of (S)-3. ECD spectroscopy was inferior to VCD in this case. The enantiomeric purity of material from five test purchases and three police seizures

cis–trans Isomerization of silybins A and B

• Michaela Novotná,
• Radek Gažák,
• David Biedermann,
• Florent Di Meo,
• Petr Marhol,
• Marek Kuzma,
• Lucie Bednárová,
• Kateřina Fuksová,
• Patrick Trouillas and
• Vladimír Křen

Beilstein J. Org. Chem. 2014, 10, 1047–1063, doi:10.3762/bjoc.10.105

• analogue that yielded suitable crystals, and hence an unequivocal determination of its absolute configuration, was 7-(4-bromobenzoyl)isosilybin A [15]. In this study the determination of the absolute configuration was based on NMR and ECD spectroscopy. Their relative configurations, i.e., the determination