Kadsuphilols A−H, Oxygenated Lignans from Kadsura philippinensis

Abstract

Eight new oxygenated lignans, kadsuphilols A-H (1-8), were isolated from the leaves and stems of Kadsura philippinensis. Four of the isolated lignans (1-4) possess the normal C18-dibenzocyclooctadiene skeleton, while the other four lignans (5-8) are C19-homolignans possessing a substituted cyclohexadienone ring with a spiro-benzofuranoid moiety. The structures of the isolated metabolites were elucidated through spectroscopic analyses, including 2D NMR experiments. Compounds 1 and 4 are the first report of an R-biphenyl configuration with a beta-oxygenated substituent at the C-9 position. The in vitro radical-scavenging activities of these compounds using DPPH were tested and evaluated. Compound 3 exhibited more potent activity than vitamins C and E.

Lignans from Schisandra sphenathera Rehd. et Wils. and semisynthetic schisantherin A analogues: Absolute configuration, and their estrogenic and anti-proliferative activity

“…The lignans from this family are commonly classified into five classes, i.e., dibenzocyclooctadiene, spirobenzofuranoid dibenzocyclooctadiene, 1,4-diarylbutane, 4-aryltetralin, and diaryltetrahydrofuran [1]. Recent pharmacological studies have revealed that these compounds accounted for anti-oxidant [2,3], anti-HIV [4,5], antihepatitis B virus [6], and anti-proliferative multiple bio-effects [7]. In addition, schisantherin A (2) has been reported to exhibit anti-inflammatory properties by down-regulating NF-kappaB and MAPK signaling pathways in lipopolysaccharide-treated RAW 264.7 cells [8].…”

Ring Expansion via Cleavage of Benzylic C−C Bonds Enabling Direct Synthesis of Medium Ring‐Fused Benzocarbocycles

“…Medium ring‐fused benzocarbocycles are important structural motifs that are ubiquitously distributed in a wide range of natural products, bioactive molecules, and even chiral ligands, such as sinensigenin C, heteroclitin I, (−)‐α‐viniferin, and cyclotriveratrylene (Figure ). Despite their importance, the creation of these appealing frameworks still remains a long‐standing challenge in the synthetic community .…”

“…This reaction provides as traightforward, transition-metal-free avenue to preparem edium ring-fused benzocarbocycles by creating "noble"s even-, eight-, and nine-membered rings. Applications of this method in the creation of medium-sized exocyclic and inner benzocyclic olefins, nine-membered lactones,a nd lactams are described.Mediumr ing-fused benzocarbocycles are important structural motifs that are ubiquitously distributed in aw ide range of natural products, bioactive molecules, and even chiral ligands, such as sinensigenin C, [1] heteroclitin I, [2] (À)-a-viniferin, [3] and cyclotriveratrylene [4] (Figure 1). Despite their importance,t he Supportinginformation for this article can be found under http:// dx.…”

Total synthesis of heliespirone B

“…1 However, oxa-Michael addition to quinone is underestimated and just stimulates few studies, 2 in spite of its potential in the total synthesis of the related natural products including kadsuphilol H, 3 gephyromycin, 4 and isopinnatal. 5 (see Fig.…”