Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

Recent advances in the Hauser annulation.

Enantiomerically pure tertiary thiols provide a major synthetic challenge, and despite the importance of chiral sulfur-containing compounds in biological and medicinal chemistry, surprisingly few effective methods are suitable for the asymmetric synthesis of tertiary thiols. This review details the most practical of the methods available.

https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-7-68.pdf

Asymmetric synthesis of tertiary thiols and thioethers

Pyranonaphthoquinones—isolation, biological activity and synthesis

Culture extracts from the cave-derived actinomycete Nonomuraea specus were investigated, resulting in the discovery of a new S-bridged pyronaphthoquinone dimer and its monomeric progenitors designated hypogeamicins A–D (1–4). The structures were elucidated using NMR spectroscopy, and the relative stereochemistries of the pyrans were inferred using NOE and comparison to previously reported compounds. Absolute stereochemistry was determined using quantum chemical calculations of specific rotation and vibrational and electronic circular dichroism spectra, after an extensive conformational search and including solute–solvent polarization effects, and comparing with the corresponding experimental data for the monomeric congeners. Interestingly, the dimeric hypogeamicin A (1) was found to be cytotoxic to the colon cancer derived cell line TCT-1 at low micromolar ranges, but not bacteria, whereas the monomeric precursors possessed antibiotic activity but no significant TCT-1 cytotoxicity.

Structure and Stereochemical Determination of Hypogeamicins from a Cave-Derived Actinomycete.

The first total synthesis and structural determination of (+)-BE-52440A

/pdf/the-first-total-synthesis-of-a-pyranonaphthoquinone-3uikeooj6b.pdf

The first total synthesis of a pyranonaphthoquinone antitumor, BE-54238B.

The first total synthesis and structural determination of (+)-BE-52440A have been achieved by enantiodivergent synthesis. S-Bridging dimerization including SN2 epoxy-opening reaction of tetrasubstituted epoxide 2 with sodium sulfide has been achieved in excellent yield with high regioselectivity. The structure of (+)-BE-52440A was determined to be the dimer of kalafungin type pyranonaphthoquinone.

Yoshikazu Suzuki

Papers

The first total synthesis and structural determination of (+)-BE-52440A

The first total synthesis of a pyranonaphthoquinone antitumor, BE-54238B.

The First Total Synthesis and Structural Determination of (+)-BE-52440A

The First Total Synthesis of a Pyranonaphthoquinone Antitumor, BE-54238B.