Elucidating the Sugar Tailoring Steps in the Cytorhodin Biosynthetic Pathway

Anthracycline antitumor cytorhodins X and Y feature a rare 9α-glycoside and 7-dexoy-aglycone. Characterization of the cytorhodin gene cluster from <i>Streptomyces</i> sp. SCSIO 1666 through gene inactivations and metabolite analyses reveals three glycosyltransferases (GTs) involved in the sugar tailoring steps. The duo of CytG1 and CytL effects C-7 glycosylation with l-rhodosamine whereas the iterative GT CytG3 and CytW similarly modifies both C-9 and C-10 positions. CytG2 also acts iteratively by incorporating the second and third sugar moiety into the trisaccharide chains at the C-7 or C-10 position

A Trifluoromethylcarbene Source

The trifluoromethylcarbene (:CHCF₃) was found to be conveniently generated from (2,2,2-trifluoro­ethyl)­diphenyl-sulfonium triflate (Ph₂S⁺CH₂CF₃ ^–OTf), which was successfully applied in Fe-catalyzed cyclopropanation of olefins, giving the corresponding trifluoromethylated cyclopropanes in high yields

Cytotoxic and Anti-inflammatory Triterpenoids from <i>Toona ciliata</i>

Toonaciliatavarins A–H (<b>1</b>–<b>8</b>), including three new protolimonoids (<b>1</b>–<b>3</b>), two new tirucallane-type triterpenoids (<b>4</b> and <b>5</b>), and three new tetranortriterpenoids (<b>6</b>–<b>8</b>), and 10 known compounds were isolated from the stem barks of <i>Toona ciliata Roem.</i> var. <i>henryi</i>. Their structures were identified on the basis of spectroscopic analysis. The absolute configurations of <b>2</b> and <b>8</b> were determined by ECD calculation. The new isolates were evaluated for their cytotoxicities using six human cancer cell lines and also for their inhibitory effects on lipopolysaccharide-induced nitric oxide production in RAW264.7 cells. Compounds <b>4</b> and <b>5</b> showed moderate cytotoxicities, and the protolimonoids (<b>1</b>–<b>3</b>) exhibited marked inhibitory effects on LPS-stimulated NO production

Penimethavone A, a flavone from a gorgonian-derived fungus <i>Penicillium chrysogenum</i>

<p>A novel flavone, penimethavone A (<b>1</b>), possessing a rare unique methyl group at ring-B, was isolated from the fungus <i>Penicillium chrysogenum</i> cultured from a gorgonian <i>Carijoa</i> sp. collected from the South China Sea. The structure was elucidated by extensive spectroscopic analysis and by comparison with related known compound. Compound <b>1</b> showed selective and moderate cytotoxicity against cervical cancer (HeLa) and rhabdomyosarcoma cell lines with IC₅₀ values of 8.41 and 8.18 μM, respectively.</p

Organocatalyzed Michael–Michael Cascade Reaction: Asymmetric Synthesis of Polysubstituted Chromans

An enantioselective cascade Michael–Michael reaction between chalcones enolates and nitromethane catalyzed by a bifunctional thiourea is developed. This reaction provides a mild but efficient approach to chiral benzopyrans bearing three consecutive stereocenters in high yields with excellent stereoselectivities, and the benzopyrans can be easily transformed to the corresponding tricyclic product

Organocatalyzed Michael–Michael Cascade Reaction: Asymmetric Synthesis of Polysubstituted Chromans

An enantioselective cascade Michael–Michael reaction between chalcones enolates and nitromethane catalyzed by a bifunctional thiourea is developed. This reaction provides a mild but efficient approach to chiral benzopyrans bearing three consecutive stereocenters in high yields with excellent stereoselectivities, and the benzopyrans can be easily transformed to the corresponding tricyclic product

Organocatalytic, Enantioselective Friedel–Crafts Reaction of Indoles in the Carbocyclic Ring and Electron-Rich Phenols

An efficient method has been successfully developed to achieve the asymmetric C–H functionalization of indoles in the carbocyclic ring via organocatalysis, and a variety of tetrahydropyranoindoles were synthesized in good yields with excellent stereoselectivities. Further study on thermodynamic calculations indicated that the process was promoted by generating more thermodynamically stable products. This strategy, together with traditional C-3 functionalization of hydroxyindoles, could realize the switchable, regiodivergent asymmetric modification of indoles

Cu-Catalyzed C–H Trifluoromethylation of 3‑Arylprop-1-ynes for the Selective Construction of Allenic Csp²–CF₃ and Propargyl Csp³–CF₃ Bonds

A new method has been developed for the Cu-catalyzed C–H trifluoromethylation of 3-arylprop-1-ynes for the selective construction of allenic Csp²–CF₃ and propargyl Csp³–CF₃ bonds. The selective formation of allenic Csp²–CF₃ and propargyl Csp³–CF₃ bonds can be controlled by modifying the reaction conditions

Bioactive Terpenoids from the Fruits of <i>Aphanamixis grandifolia</i>

From the fruits of the tropical tree <i>Aphanamixis grandifolia</i>, five new evodulone-type limonoids, aphanalides I–M (<b>1</b>–<b>5</b>), one new <i>apo</i>-tirucallane-type triterpenoid, polystanin E (<b>6</b>), and three new chain-like diterpenoids, nemoralisins A–C (<b>7</b>–<b>9</b>), along with 12 known compounds were identified. The absolute configurations were determined by a combination of single-crystal X-ray diffraction studies, Mo₂(OAc)₄-induced electronic circular dichroism (ECD) data, the Mosher ester method, and calculated ECD data. The cytotoxicities of all the isolates and the insecticidal activities of the limonoids were evaluated

Bioactive Terpenoids from the Fruits of <i>Aphanamixis grandifolia</i>

From the fruits of the tropical tree <i>Aphanamixis grandifolia</i>, five new evodulone-type limonoids, aphanalides I–M (<b>1</b>–<b>5</b>), one new <i>apo</i>-tirucallane-type triterpenoid, polystanin E (<b>6</b>), and three new chain-like diterpenoids, nemoralisins A–C (<b>7</b>–<b>9</b>), along with 12 known compounds were identified. The absolute configurations were determined by a combination of single-crystal X-ray diffraction studies, Mo₂(OAc)₄-induced electronic circular dichroism (ECD) data, the Mosher ester method, and calculated ECD data. The cytotoxicities of all the isolates and the insecticidal activities of the limonoids were evaluated