Phosphine-promoted intramolecular Rauhut-Currier/Wittig reaction cascade to access (hetero)arene-fused diquinanes

We describe the first phosphine-promoted intramolecular Rauhut-Currier reaction that triggers an intramolecular Wittig process assembling new classes of diquinanes. The one-pot strategy provides ready access to simple diquinanes and various (hetero)arene-fused diquinanes incorporated with up to two contiguous all-carbon quaternary centers under metal-free and neutral conditions. We showcased the generality of the method on a broad range of substrates and demonstrated its synthetic utility in accessing various advanced intermediates relevant to natural product synthesis and material science.

Phosphine-Promoted Ring Opening/Recyclization of Cyclopropyl Ketones to Access Hydrofluorenones

The ring-reorganizing transformations of activated cyclopropanes are typically achieved under acidic conditions. This Letter describes the first acid-free and Lewis base-mediated cascade ring opening/recyclization of designed cyclopropyl ketones to access tetrahydrofluorenones. We rationally merged the nucleophilic features of phosphines with the electronically biased cyclopropanes to synthesize several new classes of hydrofluorenones. We have also demonstrated the synthetic utility of the products in accessing highly functionalized molecular scaffolds.

A review of lignans from genus Kadsura and their spectrum characteristics

Kadsura belongs to the Schisandroideae subfamily of Magnoliaceae. Plants from genus Kadsura are widely distributed in the South and Southwest of China. The plants of the genus are widely used as folk medicine for a long time in history, with the functions of relieving pain, promoting ‘qi’ circulation, activating blood resolve stasis, and applications in the treatment of rheumatoid arthritis and gastroenteric disorders. Lignans are the primary characteristic constituents with various biological activities of plants from genus Kadsura. This paper summarized 81 lignans isolated from the plants of genus Kadsura over the past eight years (from 2014 to 2021), which belong to five types: dibenzocyclooctadienes, spirobenzofuranoid dibenzocyclooctadienes, aryltetralins, diarylbutanes and tetrahydrofurans. Each type of these lignans possess typical characteristics in proton magnetic resonance (¹H NMR) and carbon-13 nuclear magnetic resonance (¹³C NMR) spectra, the NMR regularities of these types of lingans were summarized, which provided a useful reference for the structural analysis of lignans. The relationships between lignans and pharmacodynamics were also systematically analyzed, lignans were predicted to be the quality markers (Q-marker) of Kadsura genus.

Hepatoprotective lignans and triterpenoids from the roots of Kadsura longipedunculata

Two new tetrahydrobenzocyclooctabenzofuranone lignans (1-2), a new dibenzocyclooctadiene lignan (3) and three new schiartane-type triterpenoids (4-6), together with six known compounds (7-12), were isolated from the roots of Kadsura longipedunculata. Their structures were elucidated by extensive NMR and HRESIMS spectroscopic data analysis. The absolute configurations of these compounds were determined by comparison of the experimental and calculated ECD spectra. Compound 12 exhibited moderate hepatoprotective activity against N-acetyl-p-aminophenol (APAP)-induced toxicity in HepG2 cells with cell survival rates of 53.04%.

New Lignans from the Leaves and Stems of Kadsura philippinensis

Three novel C19 homolignans, taiwankadsurins D (1), E (2) and F (4), and two new C18 lignans kadsuphilins N (3) and O (5) were isolated from the aerial parts of Taiwanese medicinal plant Kadsura philippinensis. The structures of compounds 1–5 were determined by spectroscopic analyses, especially 2D NMR techniques. The structure of compound 5 was further confirmed by X-ray crystallographic analysis. Compounds 1 and 2 have a 3,4-{1'-[(Z)-2''-methoxy-2''-oxoethylidene]}-pentano(2,3-dihydrobenzo[b]furano)-3-(2'''-methoxycarbonyl-2'''-hydroxy-2''',3'-epoxide) skeleton.

Oxygenated lignans from the fruits of Schisandra arisanensis

An acetone extract of the fruits of the Taiwanese medicinal plant Schisandra arisanensis has yielded 11 new oxygenated lignans. Four of these, named arisantetralones A-D (1-4), possess the aryltetralone skeleton, while the other seven, named arisanschinins F-L (5-11), are polyoxygenated C(18)-dibenzocyclooctadiene lignans. Structures were determined on the basis of spectroscopic analyses, especially 2D-NMR techniques. The structure of compound 1 was confirmed by X-ray crystallographic analysis. Immunomodulatory activity of the isolated lignans was tested and evaluated.

Dibenzocyclooctadiene lignans from Kadsura philippinensis

Lignans with the dibenzocyclooctadiene skeleton, kadsuphilols I-L, and one C(19)-homolignan, kadsuphilol M, were isolated by chromatographic fractionation of an ethyl acetate extract of the aerial parts of Kadsura philippinensis. Their structures were elucidated through extensive spectroscopic methods, including HRESIMS and 2D NMR experiments (HMQC, COSY and HMBC). The stereochemistry at the chiral centers and the biphenyl moist, were determined using NOESY, as well as analysis of CD spectra, respectively. The relative configuration of heteroclitin J was confirmed by single crystal X-ray crystallographic analysis. The in vitro radical-scavenging activities of these compounds by using DPPH were evaluated.