Showing papers on "Xanthone published in 1985"

Mutagenicities of xanthone derivatives in Salmonella typhimurium TA100, TA98, TA97, and TA2637.

Abstract: The mutagenicities of naturally occurring xanthones were tested in Salmonella typhimurium TA100, TA98, TA97, and TA2637 by the preincubation method. Xanthydrol, gentisein, gentisin, isogentisin, 1-hydroxy-3,7-dimethoxyxanthone, 1,3,7-trimethoxyxanthone, desmethylbellidifolin, bellidifolin and dimethylbellidifolin were mutagenic, but unsubstituted xanthone was not mutagenic to TA100, TA98, TA97 and TA2637 with or without a metabolic activation system. The beta-O-glucosides, norswertianolin and swertianolin, were only mutagenic when a metabolic activation system containing beta-glucosidase was used, and the C-glucoside mangiferin was not mutagenic even with this system.

Formation of pigments by the tissue culture of Cassia occidentalis

Abstract: From the callus of Cassia occidentalis LINN., six anthraquinones [islandicin, chrysophanol, physcion, emodin, questin, and 7-methylphyscion (1)], a bianthrone (chrysophanol-10, 10'-bianthrone), three tetrahydroanthracenes [germichrysone, methylgermitorosone, and 7-methyltorosachrysone (2)], and a xanthone (pinselin) were isolated. The structures of the two new compounds, 1 and 2, were established on the basis of spectral and chemical evidence.

Aromatic nucleophilic substitution. Part 2. Preparation of novel 3‐substituted xanthone and thioxanthone derivatives

Abstract: The novel 3-nitro-9-oxo-9H-xanthene- and 3-nitro-9-oxo-9H-thioxanthene-l-carboxylic acids 2a–d were prepared by intramolecular acylation of 3-aryloxy- and 3-arylthio-5-nitrophthalic anhydrides 1 (Scheme). The 3-nitro group was readily substituted by O- and S-nucleophiles and halide and azide ions to give a range of 3-substituted thioxanthone derivatives 3 with varied λmax.

Method for producing xanthone and thioxanthone compounds useful as photoinitiators

Abstract: A method for preparing a compound of formula I ##STR1## in which X is O or S; both groups R together with the two carbon atoms to which they are attached form a fused aromatic group; R 1 is an organic radical; and n is 0, 1, 2 or 3 comprising reacting a compound of formula II ##STR2## where R, R 1 and n are defined above and where each R 3 , independently, is C 1-12 alkoxy or one R 3 is C 1-12 alkoxy and the other R 3 is halogen, with elemental sulphur in an alkaline medium, a metal sulphide or a metal hydrosulphide. Compounds of formula I and formula II are useful as photoinitiators.

Synthesis of xanthone O‐glycosides. Part III. Synthesis of 1‐ and 8‐O‐β‐D‐glycosides of 5‐O‐methyl‐ and de‐O‐methylbellidifolin

Abstract: The unambiguous synthesis of three naturally occurring and biologically active xanthone 1-O and 8-O-β-D-glucosides of 5-O-methyl- and de-O-methylbellidifolin (2–4) was accomplished. The protected xanthone aglycones having only a single reactive OH group were prepared by selective benzylation, methylation, and debenzoylation reactions. An unexpected stability of the 1-MeO group towards demethylation was observed.

Quenching of excited-state xanthone and thioxanthone by inorganic anions

Abstract: The quenching rates of both singlet and triplet states of thioxanthone by a group of inorganic anions have been determined, enabling a comparison of their reactivities. The quenching rates of triplet xanthone were also measured. All determinations were made in MeCN–H2O (3 : 2 v/v). The various rates are correlated with the free-energy change for electron-transfer, ΔG23°, according to the treatments of Rehm and Weller and of Polanyi; an unexpectedly good fit is given by the latter.

Xanthone analogue of geiparvarin.

Abstract: The synthesis and the pharmacological properties of the xanthone analogue of geiparvarin, a naturally occurring antitumor coumarin, are described. Xanthon-Analogon des Geiparvarins Die Synthese und die pharmakologischen Eigenschaften des Xanthon-Analogon, eines in der Natur vorkommenden antitumoralen Cumarins, Geiparvarin, werden beschrieben.

Production of aromatic polyketone

Abstract: PURPOSE: To obtain a high-quality polyketone at low temperatures in a short time, by using, as a polymerization solvent, specific (thio)xanthone compound to homogeneously dissolve the polymer formed in said solvent to prevent gelation due to local heating. CONSTITUTION: Using, as a solvent, a xanthone or thioxanthone compound of formula I (R and R' are each H, 1W3C alkyl or phenyl; Y is O or S), (A) 4-hydroxythiophenol and (B) 4,4'-dihaloterephthalophenone or 4,4'- dihalobenzophenone are brought to polycondensation to obtain the objective crystalline poly-(etherthioether aromatic ketone) with an intrinsic viscosity ≥0.4 having linear polymer structure in which structural unit of formula II or III and that of formula IV are alternately linked with each other. COPYRIGHT: (C)1987,JPO&Japio

Aromatic nucleophilic substitution. part 2. preparation of novel 3-substituted xanthone and thioxanthone derivatives

Abstract: The novel 3-nitro-9-oxo-9H-xanthene- and 3-nitro-9-oxo-9H-thioxanthene-l-carboxylic acids 2a–d were prepared by intramolecular acylation of 3-aryloxy- and 3-arylthio-5-nitrophthalic anhydrides 1 (Scheme). The 3-nitro group was readily substituted by O- and S-nucleophiles and halide and azide ions to give a range of 3-substituted thioxanthone derivatives 3 with varied λmax.