Functional biosynthetic stereodivergence in a gene cluster via a dihydrosydnone N-oxide.

Chirality plays a critical role in the biochemistry of life and often only one enantiomeric series is observed (homochirality). Only a few natural products have been obtained as racemates, e.g.

Total Synthesis of (-)-Bipolarolide D.

(-)-Bipolarolide D is an ophiobolin-derived sesteterpenoid with a unique tetraquinane (5/5/5/5) tetracyclic skeleton decorated with a diverse set of functionalities. Herein we report a robust, scalable, and efficient total synthesis of this natural product in 1.8% overall yield.

Switching Residues: A Platform for the Synthesis of Fidaxomicin Antibiotics.

Peripheral modification is often the main approach to optimize natural products for improved biological activity or desired physicochemical properties. This procedure inevitably increases molecular weight, often accompanied by undesired increased lipophilicity. Removing structural elements from natural products is not always tolerated.

UV-vis absorbance spectra, molar extinction coefficients and circular dichroism spectra for the two cyanobacterial metabolites anabaenopeptin A and anabaenopeptin B.

The UV-vis absorbance spectra, molar extinction coefficients and circular dichroism spectra, as well as NMR and high resolution tandem mass spectrometry spectra were determined for two prominent secondary metabolites from cyanobacteria, namely anabaenopeptin A and anabaenopeptin B. The compounds were extracted from the cyanobacterium CBT929 and purified by flash chromatography and HPLC. Exact amounts of isolated compounds were assessed by quantitative H-NMR with internal calibrant ethyl 4-(dimethylamino)benzoate in DMSO‑ at 298 K with a recycle delay (d1) of 120 s.

Formal Single Atom Editing of the Glycosylated Natural Product Fidaxomicin Improves Acid Stability and Retains Antibiotic Activity.

Fidaxomicin (Fdx) constitutes a glycosylated natural product with excellent antibacterial activity against various Gram-positive bacteria but is approved only for infections. Poor water solubility and acid lability preclude its use for other infections. Herein, we describe our strategy to overcome the acid lability by introducing acid-stable S-linked glycosides.