Search results for "Indole"

Synthesis of pyrrolo[3′,4′:2,3]azepino[4,5,6-cd]indole-8,10-diones

2000

3-Amino-4-(3-indolyl)pyrrolin-2,5-diones are condensed with various aldehydes and ketones to the cor responding imines. Under Pictet-Spengler conditions, the latter do not cyclize to pyrrolo-β-carbolines, but readily yield pyrrolo[3′,4′:2,3]azepino[4,5,6-cd]indole-8,10-diones.

2H -[1,3]Oxazino[3,2-α]indolin-4(3H )-ones: A Class Of Polyheterocyclic Indole-Based Compounds

2018

Palladium-catalyzed dehydrogenative β'-functionalization of β-keto esters with indoles at room temperature.

2012

The dehydrogenative β′-functionalization of α-substituted β-keto esters with indoles proceeds with high regioselectivities (C3-selective for the indole partner and β′-selective for the β-keto ester) and good yields under mild palladium catalysis at room temperature with a variety of oxidants. Two possible mechanisms involving either late or early involvement of indole are presented.

The Halide Binding Behavior of 2-Carbamoyl-7-ureido-1H-indoles: Conformational Aspects

2009

Indole-based anion receptors with an carboxamide unit in 2- and an urea in 7-position were prepared and found to bind halides (as well as acetate and nitrate) in chloroform solutions at room temperature. Investigations of the binding behaviour show that the receptor is selective for chloride. Surprisingly, the truncated receptor 3 without the 2-carbamoyl substituent shows the highest affinity for Cl–. Thorough 1H, 13C and 15N NMR investigations indicate different binding modes for acetate, nitrate and halides to the receptor 2. The observation of a major conformational change of this receptor during the binding of the halide ions leads to an understanding of the relative binding affinities …

Zur Regiochemie von [4 + 2]-Cycloadditionen mit Methylpyrano[3,4-b]indol-3-onen und unsymmetrischen Dienophilen

1989

Die methylierten Pyrano[3,4-b]indol-3-one 1a, 1b reagieren mit acyclischen, unsymmetrischen CC-Dienophilen nach einer Diels-Alder-Reaktion/CO2-Extrusion zu selektiv funktionalisierten Carbazolen 2. In Abhangigkeit von der Struktur der Reaktionspartner wird keine oder geringe bis hohe Regioselektivitat festgestellt. Diethylmesoxalat reagiert mit 1a, 1b regioselektiv zu neuen 2,3-difunktionalisierten Indolen 4a, 4b, die aus einer regiokontrollierten [4 + 2]-Cycloaddition und Cycloreversion resultieren, wobei Pyrano[3,4-b]indoldicarbonsaure-diethylester 3a, 3b als Intermediate auftreten durften. Regiochemistry of [4 + 2] Cycloadditions with Methylpyrano[3,4–b]indol-3-ones and Unsymmetric Dieno…

Zur Reaktion vonE/Z-N-Benzolsulfonyl-3(2-methoxyvinyl)-indol mit Carbo- und Heterodienophilen: NeueDiels-Alder-Addukte aus der Indol- bzw. Carbazol-R…

1987

E/Z-Benzenesulfonyl-3(2-methoxyvinyl)-indole1 reacts viaDiels-Alder type mechanism with dimethyl acetylendicarboxylate, N-phenyltriazolindione and diethyl mesoxalate to give new cycloadducts2–5 with [b]annellated indole structures.

The reactivity of 2-vinylindoles with dimethyl acetylenedicarboxylate

1984

Abstract The overall rates of reaction of 1-substltuted-1- (1-methyl-2-indolyl)ethenes with dimethyl acetylenedicarboxylate are considerably lower than those of the corresponding 2-vinyl- pyrroles. Steric interaction between the N-methyl group on the indole ring and the 1-substituent on the ethenyl group prevents the diene system adopting a coplanar cisoid configuration and, thereby, inhibits the π4 + π2 cycloaddition reaction of the system with dimethyl acetylenedicarboxylate. Under such conditions, the indolylethene preferentially undergoes a Michael addition reaction at the 3-position. The π4 + π2 cycloaddition reaction is promoted at elevated temperatures. No evidence was found for a Co…

ChemInform Abstract: Cross-Dehydrogenative Couplings Between Indoles and β-Keto Esters: Ligand-Assisted Ligand Tautomerization and Dehydrogenation vi…

2014

Cross-dehydrogenative coupling reactions between β-ketoesters and electron-rich arenes, such as indoles, proceed with high regiochemical fidelity with a range of β-ketoesters and indoles. The mechanism of the reaction between a prototypical β-ketoester, ethyl 2-oxocyclopentanonecarboxylate, and N-methylindole has been studied experimentally by monitoring the temporal course of the reaction by (1)H NMR, kinetic isotope effect studies, and control experiments. DFT calculations have been carried out using a dispersion-corrected range-separated hybrid functional (ωB97X-D) to explore the basic elementary steps of the catalytic cycle. The experimental results indicate that the reaction proceeds v…

Capillary zone electrophoresis of alkaloids

1998

Abstract A comprehensive discussion of important aspects for the analysis of alkaloids by capillary zone electrophoresis (CZE) is given. The influence of structure on the electrophoretic mobility (EM) of indole alkaloids was investigated using a running buffer which is generally applicable to the CZE analysis of alkaloids. The EM, which at the applied conditions was mostly dependent on the size and shape of the solvated analyte ions, was additionally affected by the presence of hydrogen bonds or ion–dipole interactions between protonated and unprotonated alkaloids of the same species. This could be derived from the existence of alkaloidal dimer cluster ions [2M+H]+ when mass spectrometry wa…

General approach for the analysis of various alkaloid classes using capillary electrophoresis and capillary electrophoresis-mass spectrometry

1997

Abstract The analysis of various alkaloid classes employing capillary electrophoresis (CE) and on-line combined CE-mass spectrometry (CE-MS) is described. A CE method is presented for the analysis of alkaloids without derivatisation or purification. The separation of four different groups of alkaloids consisting of monoterpenoid indole alkaloids, protoberberines/benzophenanthridines, β-carboline alkaloids, and isoquinolines from poppy by free zone capillary electrophoresis has been obtained using a 1:1 mixture of 100 mmol 1 −1 ammonium acetate (pH 3.1) and acetonitrile. The influence of alkaloid structure on the electrophoretic mobility is discussed. The CE-MS reconstructed total ion curren…