Organic xanthone

Not all the red pigments from the organisms were anthraquinones. A xanthone, rubrofusarin (7.12), has been obtained from several organisms. Many members... 

Palladium migration is a mechanistically interesting and synthetically useful process, because it provides an indirect approach to introduce palladium to a specific location in an organic molecule. It also allows C-H activation to occur on a remote site whose direct functionalization may not be easily achieved. Through the years, palladium migration processes have been applied to the construction of a variety of important heterocycles, such as carbazoles [25, 26], indoles [26], xanthones [27], and fluoren-9-ones [27, 28], They have also received special attention from computational chemists, who have conducted theoretical studies on the mechanism and transition state [29-31],... 

Xanthones have been identified in different species, such as H. perforatum [9,10,22], II. inodorum, H. calycinum and H. roeperanum [72], mainly in the underground organs. 

Several xanthones have also been isolated from the aerial organs of H. ascyron [73], a Chinese natural drug used in the treatment of headache, nausea and abscesses. 

Clusiaceae (Guttiferae) is a family almost exclusively tropical in distribution and comprises about 40 genera and 1200 species most of which are woody [1], Extensive phytochemical studies have shown Clusiaceae to be a rich source of secondary metabolites including xanthones, triterpenoids, flavonoids, lactones and organic acids. In addition plants of this family produce a series of oxidized and polyisoprenylated benzophenones (PBDs), some of which are structurally complex and biologically active. 

Frequently, co-solvents are added to aqueous cyclodextrin solutions in most cases, these co-solvents are employed to solubilize the probes. In Section IV.C, the decrease of the exit rate constant of triplet xanthone from CDs with the addition of alcohols was described. This effect was also apparent when studying the dynamics of 1-halonaphthalenes with P-CD in the presence of acetonitrile [141]. When the nitrite ion was used as quencher, the association rate constants decreased in the presence of the organic solvent while the dissociation rate constant increased (Table 21). The main rationalization to explain the change in mobility properties was that acetonitrile was small enough to coinclude inside the cavity a small amount of acetonitrile could preferentially solvate the entrances of the CD thereby leading to a different environment for the probe. 

Phytochemistry The total flavonoids isolated from this species are nearly identical to those of Hypericum perforatum. Xanthones, vitamin C, carotene, anthocyanins, essential oil, sugars, mucilage, resins, organic acids, and saponins and others have also been isolated from the plant (Plant Resources of the USSR 1986 Matsuhisa et al. 2002 Tanaka et al. 2004). 

Organic synthesis of C-prenylated phenoHc compounds, flavonoids, and xanthones 13COC1067. 

Maleimide. Maleimide and maleic anhydride are simple olefins and very useful molecules in organic syntheses for introducing various substituents. Addition reactions, cyclodimerization, Diels-Alder reactions and polymerization reactions are as well-known as their photochemical reactions. They are also known as electron acceptors in photoinduced electron-transfer reactions. The photosensitized reaction of maleimide with xanthone in 2-propanol has been investigated by TR EPR. The emissive CIDEP spectrum observed in 2-propanol is predominantly assigned to two kinds of maleimide alkyl-type radicals. On the other hand, the absorptive spectrum of the maleimide radical-anion was observed in 2-propanol in the presence of hydrochloric acid. The hydrochloric acid addition effect on the CIDEP patterns indicates the existence of two mechanisms for the photosensitization of maleimide by xanthone. One is a T-T energy transfer to maleimide followed by hydrogen abstraction by maleimide... 

Position of infrared band in xanthone complex Basis for ranking Heat evolved on association with oxygenated organic compounds Acylation rates Friedel-Crafts catalysis ... 

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