Total Synthesis of the Proposed Structure for Aromin and Its Structural Revision

Azaphilones from the Fungus Penicillium multicolor LZUC-S2 and Their Antibacterial Activity

Two new azaphilones, penimultiones A and B, together with seven known analogs were isolated from the culture of Penicillium multicolor LZUC-S2. Their structures were elucidated by detailed spectroscopic data analysis and chemical transformation. Penimultiones A and B belong to a rare class of azaphilones possessing a 1,3-dioxolane moiety. In addition, all compounds were evaluated for their antibacterial activity against five clinically bacterial strains in vitro, and three compounds showed potent antibacterial activity with minimum inhibitory concentration (MIC) values ranging from 12.5 to 50.0 μg/mL.

Total synthesis: the structural confirmation of natural products

This feature article highlights total synthesis as one of the reliable tools for the structural confirmation of natural products.

Total synthesis and complete configurational assignment of amphirionin-2

Amphirionin-2 is a linear polyketide metabolite that exhibits potent and selective cytotoxic activity against certain human cancer cell lines. We disclose herein the first total synthesis of amphirionin-2 and determination of its absolute configuration. Our synthesis featured an extensive use of cobalt-catalyzed Mukaiyama-type cyclization of γ-hydroxy olefins for stereoselective formation of all the tetrahydrofuran rings found in the natural product, and a late-stage Stille-type coupling for convergent assembly of the entire carbon backbone. Four candidate diastereomers of amphirionin-2 were synthesized in a unified, convergent manner, and their spectroscopic/chromatographic properties were compared with those of the authentic material. The present study culminated in the reassignment of the C5/C7 relative configuration, assignment of the C12/C18 relative configuration, and determination of the absolute configuration of amphirionin-2.

Rapid Construction of the Scaffold of Quorumolide A Enabled by a Tandem ROM/RCM Strategy and a Tandem Oxidative Cyclization Strategy

A synthetically challenging framework in the plant-derived cembranoid quorumolide A was established in a seven-step sequence featuring a ring-opening/-closing metathesis cascade reaction to construct the fused butenolide ring and the 14-membered macroring in a single step. The utilization of a tandem oxidative cyclization strategy is the key to build the tetrahydro-2H-pyran moiety.

The value of universally available raw NMR data for transparency, reproducibility, and integrity in natural product research

Covering: up to 2018With contributions from the global natural product (NP) research community, and continuing the Raw Data Initiative, this review collects a comprehensive demonstration of the immense scientific value of disseminating raw nuclear magnetic resonance (NMR) data, independently of, and in parallel with, classical publishing outlets. A comprehensive compilation of historic to present-day cases as well as contemporary and future applications show that addressing the urgent need for a repository of publicly accessible raw NMR data has the potential to transform natural products (NPs) and associated fields of chemical and biomedical research. The call for advancing open sharing mechanisms for raw data is intended to enhance the transparency of experimental protocols, augment the reproducibility of reported outcomes, including biological studies, become a regular component of responsible research, and thereby enrich the integrity of NP research and related fields.