Two sequential Suzuki coupling reactions have been developed for efficient synthesis of synthetically and biologically important 3,6-disubstituted 2,5-dioxybenzoquinone architectures in a highly chemoselective controlled manner. The method serves as a key step in the total synthesis of leucomelone in three steps and in 61% overall yield.

Extracts of Toona sinensis shoots were studied to identify the precursors of volatile sulfur-containing flavor molecules. T. sinensis was found to contain new compounds (S,S)-γ-glutamyl-(cis-S-1-propenyl)thioglycine, 1, (S,S)-γ-glutamyl-(trans-S-1-propenyl)thioglycine, 2, and γ-glutamyl-(cis-S-1-propenyl)-cysteine, 3. The structures of these compounds were determined by interpretation of multistage mass spectrometric (MS(n)), 1D, and 2D NMR data. The absolute configuration of 1 was established by comparison of experimental with computed infrared and vibrational circular dichroism spectra. Because of the flexibility of the molecule and the novelty of the structure, the configuration was further confirmed by X-ray crystallography. Compounds 1 and 2 are the first examples of norcysteine-containing metabolites reported from nature. They may release thiols via cleavage of the amide bond by proteases, followed by spontaneous decomposition of the resulting unstable alk(en)yl norcysteine moiety.

A novel withanolide, withaphysalin P (1) with a nine‐membered ring, and six other new withaphysalins, 2–7, together with the three known withaphysalins 8–10 were isolated from Physalis minima L. The structures were deduced by means of spectroscopic analyses, and that of withaphysalin P (1) was confirmed by a single‐crystal X‐ray diffraction analysis. Plausible biosynthetic pathways were postulated (Scheme 1). All compounds were tested for their antiproliferative activities toward the human colorectal‐carcinoma HCT‐116 cells and human nonsmall‐cell lung‐cancer NCI‐H460 cells (Table 4). Compounds 1–3, 7–10, 7a, and 7b displayed moderate cytotoxic activity against the two human cancer cell lines.