A biochemical, structural and mechanistic perspective on the pathways of sulfoglycolysis for catabolism of the sulfosugar sulfoquinovose.

The total synthesis of nyingchinoids Aa nd Bh as been achieved through successive rearrangements of a1 ,2dioxane intermediate that was assembled using av isible-light photoredox-catalysed aerobic [2+ +2+ +2] cycloaddition. Nyingchinoid Dw as synthesised with ac ompeting [2+ +2] cycloaddition. Based on NMR data and biosynthetic speculation, we proposed as tructure revision of the related natural product rasumatranin D, which was confirmed through total synthesis. Under photoredoxc onditions,w eo bserved the conversion of ac yclobutane into a1 ,2-dioxane through retro-[2+ +2] cycloaddition followed by aerobic [2+ +2+ +2] cycloaddition. Scheme 1. Proposed biosynthesis of nyingchinoidsA,

The structure of furoerioaustralasine, a unique Australian alkaloid, has been revised based on a concise, biomimetic synthesis. The key step is a stereospecific, intramolecular ring opening of an epoxide to form a central dihydrofuran fused to a quinoline ring system.

Chiral hydroxy- and aminohydroxysulfonic acids are widespread in the marine and terrestrial environment. Here we report simple methods for the synthesis of d- and l-cysteinolic acid (from (Boc-d-Cys-OH)2 and (Boc-l-Cys-OH)2, respectively), R- and S-3-amino-2-hydroxypropane­sulfonate (from S- and R-epichlorohydrin, respectively), and R- and S-2,3-dihydroxy­propane­sulfonate (from S- and R-epichlorohydrin, respectively). d-Cysteinolate bile salts were generated by coupling with cholic and chenodeoxycholic acids. A series of single-crystal 3D X-ray structures confirmed the absolute configurations of the aminosulfonates. By comparison of optical rotation, we assign naturally occurring 3-amino-2-hydroxypropanesulfonate from Gateloupia livida as possessing the R-configuration. This simple synthetic approach will support future studies of the occurrence, chemotaxonomic distribution, and metabolism of these alkylsulfonates.

Singlet oxygen is a versatile reagent for the selective oxidation of organic compounds under mild reaction conditions. It is frequently invoked in biosynthetic pathways, so it is especially suitable for application in the biomimetic synthesis of natural products. Herein, we show that use of the singlet oxygen ene reaction, combined with [2 + 2] cycloadditions, leads to concise, divergent, and redox-economic total syntheses of several polycyclic members of the rhodonoid family of meroterpenoids.