Four new iridoids structurally related to gelsemide (5) were isolated from two Loganiaceous plants, Gelsemium elegans and G. rankinii. Among them, GEIR-1 (1) has a novel tetracyclic caged structure.

Many existing degree based topological indices can be clasified as bond incident degree (BID) indices, whose general form is BID(G) = ∑ uv∈E(G) Ψ(du, dv), where uv is the edge connecting the vertices u, v of the graph G, E(G) is the edge set of G, du is the degree of the vertex u and Ψ is a non-negative real valued (symmetric) function of du and dv. Here, it has been proven that if the extensio...

The MeOH extract from dried aerial parts of Oxypetalum caeruleum (Apocynaceae) plants yielded seventeen compounds, including four new tetracyclic triterpenoids, one pregnane glycoside, two lignane glycosides, and ten known compounds. structures the compounds were established using NMR, MS spectroscopic analysis chemical evidence.

Five novel chromones (1,4-benzopyran-4-ones), among which three are tetracyclic and one contains a sulfonyl group, have been isolated from an Ascomycete, Chaetomium quadrangulatum, as monoamine oxidase inhibitory features, and named chaetoquadrins A (1)-E (5).

An arene-terminated epoxy olefin cyclization was promoted by a water-tolerant Lewis acid to give tri- and tetracyclic 3beta-hydroxy terpenoids and steroid derivatives in 57 and 37% yields, respectively, per new formed ring up to 75%.

The enantioselective synthesis of advanced tetracyclic precursors of madangamine D, bearing rings ABCD of this alkaloid, is reported. The saturated 14-membered ring is assembled from functionalized diazatricyclic intermediates following either ring-closing metathesis or macrolactamization strategies.

The limits of a recently proposed computer method for finding all distinct substructures of a chemical structure are systematically explored within comprehensive graph samples which serve as supersets of the graphs corresponding to saturated hydrocarbons, both acyclic (up to n = 20) and (poly)cyclic (up to n = 10). Several pairs of smallest graphs and compounds are identified that cannot be dis...

An efficient access to the tetracyclic-fused quinoline systems, 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives 4a-l, is described, involving the intramolecular Friedel-Crafts acylation reaction of 2-(phenoxymethyl)-4-phenylquinoline-3-carboxylic acid derivatives 3a-l aided by the treatment with PPA (polyphosphoric acid) or Eaton's reagent. The required starting compound (2) wa...

Cholesterol is a major and essential constituent in higher eukaryotic cellular membranes and is crucial in membrane organization, dynamics, function, and sorting (Liscum and Underwood 1995 ; Simons and Ikonen 2000 ; Mouritsen and Zuckermann 2004 ) . Cholesterol is a predominantly hydrophobic molecule comprising a near planar tetracyclic fused steroid ring and a fl exible isooctyl hydrocarbon ta...

Asymmetric Conjugate Addition of ortho-Quinone Methides as a Pathway to the Core of Nomofungin Introduction: Tetracyclic structures are found at the core of many biologically active molecules. One class of compounds with a tetracyclic core is the family of communesin products. 1 These products have shown cytotoxicity against several leukemia cell lines as well as insecticidal activity against s...