Search results for "cyclic"
showing 10 items of 2439 documents
Electrochemical oxidation of substituted pyrroles.III.Anodic oxidation of 2,5-diphenyl-3-acetylpyrrole
1991
The electrochemical oxidation of 2,5-diphenyl-3-acetylpyrrole (I) is described. The cyclic derivative 1,6a-dihydro-2,5,6a-triphenyl-3,4-diacetylbenzo[g]pyrrolo[3,2-e]indole (II) was obtained in very good yield. However, when water was present in the reaction medium, a different derivative, 4-acetyl-2-hydroxy-2,5-diphenyl-3-(4′-acetyl-2′,5′-diphenyl-3′-yl)-2H-pyrrole (III), was obtained as the main product. 2,2′,5,5′-Tetraphenyl-4,4′-diacetyl-3,3′-dipyrryl (IV), a potentially useful intermediate for the synthesis of condensed pyrroles, was synthesized by zinc reduction of III.
Polycondensed nitrogen heterocycles. Part13. Pyrrolo[3,2-b]indole by intramolecular nucleophilic substitution reaction in the pyrrole series
1984
An intramolecular nucleophilic substitution in the pyrrole series has been generalized. The behaviour of nitro, chlorine, bromine and iodine as leaving groups towards the nucleophilic amino group was observed. An acid catalyzed mechanism has been proposed.
The Reactions of Electron-Rich Heterocycles with Derivatives of Orthocarboxylic Acids; VIII. Proton Acid-Catalyzed Acylation of Indoles by 2-Alkoxy-1…
1987
In acid-catalyzed reactions with 3-unsubstituted indoles 1, 2-alkoxy-1,3-dioxolanes 2a-c behave as acyl equivalents. Depending on the substitution patterns of the reaction partners, the 1,3-dioxolanium ions 3a-c, generated in situ from the cyclic ortho esters by the action of sulfosalicylic acid, react to form tris-(3-indolyl)alkanes 6 and 9, bis-(3-indolyl)ethenes 7, or 3-benzoylindoles 8. Analogous reactivity was observed with related acyclic ortho esters. Reaktionen elektronenreicher Heterocyclen mit Orthocarbonsaure-Derivaten; VIII. Protonsaurekatalysierte Acylierung von Indolen mit 2-Alkoxy-1,3-dioxolanen 2-Alkoxy-1,3-dioxolane 2a-c reagieren als Acylaquivalente mit 3-unsubstituierten …
Investigations on the content indole-3-acetic spruce needles of healthy and damaged trees of various sites
1993
Summary Surveys were made on the concentration of indole-3-acetic acid (IAA) in spruce trees of various sites. The concentrations of the hormone were specified with a radioimmunoassay after the needle extract had been purified in several steps. The content of IAA in needles of damaged trees was distinctly lower than the content in needles of healthy trees. Another feature was the annual rythm of the IAA content with the maximum of concentration in June. A distinct diurnal course with highest level of concentration during the early afternoon hours was also observed. The diurnal rhythm of the damaged trees was clearly lower. The supposition is that the lower IAA content is responsible for a p…
Regioselective proton-catalyzed diarylmethylation of indoles with 9H-xanthydrol, dibenzosuberenol, and bis[4-dimethylaminophenyl]methanol
1988
3-Isopropylindole (4) is xanthenylated both at N-1 (stereocontrolled major reaction), C-2, and on the phenyl nucleus of the indole skeleton by xanthydrol (1). Other carbinols such as dibenzosuberenol (2) and bis[4-dimethylaminophenyl]methanol (3) with lower electrophilic SN1 activities than 1 do not react with 4 but do react very selectively with simple methylindoles to form diarylmethylated derivatives.
Induction of alkaloid diversity in hybrid plant cell cultures
1999
The treatment of Rauwolfia serpentina x Rhazya stricta somatic hybrid cell suspension culture with 100 μM of methyl jasmonate led to a general increase in indole alkaloid content and to qualitative changes in the alkaloid pattern. The content of Six alkaloids were investigated with respect to their content in both the cell biomass and nutrition medium. Intracellular 17-O-acetyl-norajmaline content on the 5th day after treatment had increased about 40-fold compared with the control culture. The respective concentrations of the other alkaloids increased by a factor of two to five. In total 26 indole alkaloids were identified in extracts of the methyl jasmonate-treated culture by TLC, UV, MS a…
Geldanamycin and its derivatives as Hsp90 inhibitors
2012
The Hsp90 molecule, one of the most abundant heat shock proteins in mammalian cells, maintains homeostasis and prevents stress-induced cellular damage. Hsp90 is expressed under normal conditions at a level of about 1-2 Percent of total proteins, while its expression increases 2-10 fold in cancer cells. The two main constitutively expressed isoforms of Hsp90 are known as Hsp90-alpha and Hsp90-beta, and their upregulation is associated with tumor progression, invasion and formation of metastases, as well as development of drug resistance. The Hsp90 is a key target for many newly established, potent anticancer agents containing Hsp90 N-terminal ATP binding inhibitors, such as geldanamycin, and…
Synthesis and evaluation of microtubule assembly inhibition and cytotoxicity of prenylated derivatives of cyclo-l-Trp-l-Pro
2000
The synthesis of three isoprenylated derivatives of cyclo-L-Trp-L-Pro is described. These substances have been evaluated for cytotoxic activity in rat normal fibroblast 3Y1 cells and have also been evaluated in vitro for the inhibition of microtubule assembly.
Hydantoin-substituted 4,6-dichloroindole-2-carboxylic acids as ligands with high affinity for the glycine binding site of the NMDA receptor.
2002
A novel series of C-3 substituted 4,6-dichloroindole-2-carboxylic acids was synthesized to investigate the influence of different hydrogen-bond donor and acceptor groups at this specific position on the affinity to the glycine site of the NMDA receptor. These novel 3-indolylmethyl derivatives with ring-open (amines, sulfonamides, amides, ureas) and cyclic substituents (imidazolidin-2-ones, (thio)hydantoins) led to the discovery that compounds bearing a hydantoin substituent at the C-3 position of the indole nucleus are the most promising ones. In this series the hydantoins, ureas, and imidazolidin-2-ones were identified as very potent inhibitors of the binding of the glycine site specific l…
Production of cyclopiazonic acid by molds isolated from Taleggio cheese
1999
Twenty-seven strains of Penicillium were isolated from the rind of Taleggio, a typical Italian cheese, so that we could test their capacity to produce cyclopiazonic acid (CPA); all strains produced CPA. The production was strongly influenced by the strain variety and growth conditions. Strains incubated at 25 degrees C for 7 days always produced CPA in mannitol broth, with concentrations ranging from 0.02 to 1 microg/ml, whereas only 33% of strains grown in yeast-extract broth produced CPA, with a maximum value of 0.1 microg/ml. In milk, maximum production (1.6 microg/ml) was observed after 14 days of incubation at 25 degrees C. In order to evaluate the presence of the toxin and its capacit…