A practical three-step protocol for the assembly of triazolobenzodiazepine-fused diketopiperazines and hydantoins has been developed. The synthesis of these tetracyclic ring systems was initiated by an Ugi reaction, which brought together all necessary functionalities for further transformations. The Ugi adducts were then subjected to a base-induced ring closing and an intramolecular azide-alky...

DESCRIPTION Celexa (citalopram HBr) is an orally administered selective serotonin reuptake inhibitor (SSRI) TM with a chemical structure unrelated to that of other SSRI’s or of tricyclic, tetracyclic, or other available antidepressant agents. Citalopram HBr is a racemic bicyclic phthalane derivative designated (±)-1-(3-dimethylaminopropyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitr...

mean labelings are a type of additive vertex labeling. this labeling assigns non-negative integers to the vertices of a graph in such a way that all edge-weights are different, where the weight of an edge is defined as the mean of the end-vertex labels rounded up to the nearest integer. in this paper we focus on mean labelings of some graphs that are the result of the corona operation. in parti...

A series of novel benzosuberone derivatives were synthesized and evaluated as antimicrobial agents by using substituted benzosuberone derivatives 1a,b as starting materials. Treatment of 1a,b with phenyl isothiocyanate in dimethylformamide was followed by treatment with cold HCl solution to afford the thioamides 4a,b, which was reacted with methyl iodide to obtain methylated products 5a,b. Cycl...

Chromomycin A3 is an antitumor drug produced by Streptomyces griseus subsp. griseus. It consists of a tricyclic aglycone with two aliphatic side chains and two O-glycosidically linked saccharide chains, a disaccharide of 4-O-acetyl-D-oliose (sugar A) and 4-O-methyl-D-oliose (sugar B), and a trisaccharide of D-olivose (sugar C), D-olivose (sugar D), and 4-O-acetyl-L-chromose B (sugar E). The chr...

the edge tenacity te(g) of a graph g is dened as:te(g) = min {[|x|+τ(g-x)]/[ω(g-x)-1]|x ⊆ e(g) and ω(g-x) > 1} where the minimum is taken over every edge-cutset x that separates g into ω(g - x) components, and by τ(g - x) we denote the order of a largest component of g. the objective of this paper is to determine this quantity for split graphs. let g = (z; i; e) be a noncomplete connected spli...

the energy of a graph is equal to the sum of the absolute values of its eigenvalues. two graphs of the same order are said to be equienergetic if their energies are equal. we point out the following two open problems for equienergetic graphs. (1) although it is known that there are numerous pairs of equienergetic, non-cospectral trees, it is not known how to systematically construct any such pa...

let $g=(v, e)$ be a graph. by emph{directional labeling (ord-labeling)} of an edge $x=uv$ of $g$ by an ordered $n$-tuple$(a_1,a_2,...,a_n)$, we mean a labeling of the edge $x$ such thatwe consider the label on $uv$ as $(a_1,a_2,...,a_n)$ in thedirection from $u$ to $v$, and the label on $x$ as$(a_{n},a_{n-1},...,a_1)$ in the direction from $v$ to $u$. inthis paper, we study graphs, called emph{...

In the present work, we report a convenient synthesis of 5- and 7-substituted-4-phenyl coumarins. contrast to previous results obtained with 4-alkylcoumarins, nicotinoylation 5,7-dihydroxy-4-phenylcoumarin nicotinoyl benzotriazole or azide selectively provides 5-O protected ester. The combination reaction followed by tosylation-denicotinoylation yields 5-hydroxy-7-tosyloxy-coumarin derivative, ...

The roots of Euphorbia kansui are considered an important traditional folk medicine. In this study the ethanol extracts of E. kansui were investigated. A new tetracyclic triterpenoid, euphane-3b,20-dihydroxy-24-ene, in addition to five known triterpenoids with euphane skeletons were isolated. Their structures were elucidated on the basis of physical and spectral techniques (1D-, 2D-NMR and MS, ...