Search results for "Indole test"

Hydroxy-Directed Enantioselective Hydroxyalkylation in the Carbocyclic Ring of Indoles

2017

[EN] A Cinchona-derived squaramide catalyzes the reaction between hydroxyindoles and isatins leading to enantioenriched indoles substituted in the carbocyclic ring. The reaction proceeds efficiently with differently substituted isatins, yielding the desired products with excellent regioselectivity, good yields, and high enantiocontroi. Moreover, every position of the carbocyclic ring of the indole can be functionalized by using the appropriate starting hydroxyindole. The OH group was removed smoothly upon hydrogenolysis of the corresponding triflate.

Enantioselective Synthesis of 2-Amino-1,1-diarylalkanes Bearing a Carbocyclic Ring Substituted Indole through Asymmetric Catalytic Reaction of Hydrox…

2018

[EN] An asymmetric catalytic reaction of hydroxyindoles with nitroalkenes leading to the Friedel-Crafts alkylation in the carbocyclic ring of indole is presented. The method is based on the activating/directing effects of the hydroxy group situated in the carbocyclic ring of the indole providing nitroalkylated indoles functionalizated at the C-4, C-5, and C-7 positions with high yield, regio-, and enantioselectivity. The optically enriched nitroalkanes were transformed efficiently in optically enriched 2-amino-1,1-diarylalkanes bearing a carbocyclic ring substituted indole.

From Benzofurans to Indoles: Palladium-Catalyzed Reductive Ring-Opening and Closure via β-Phenoxide Elimination

2018

International audience; Benzofurans can undergo ring-opening by a palladium-catalyzed process resulting in C−O bond breaking. Benzofuran-tethered 2-iodoanilines give synthetically interesting 2-(3-indolylmethyl)phenols in an overall reductive process. Mechanistic studies suggest that this unusual reaction proceeds by carbopalladation of benzofuran giving a 3-palladated 2,3-dihydrobenzofuran intermediate, which then fragments by an uncommon trans-elimination of the phenoxide group β to the metal. In this transformation, N,N-diisopropylethylamine (DIPEA) acts as a base and as a reducing agent: it regenerates palladium(0) from palladium(II), thus allowing catalytic turnover.

Straight Access to Indoles from Anilines and Ethylene Glycol by Heterogeneous Acceptorless Dehydrogenative Condensation.

2017

The development of original strategies for the preparation of indole derivatives is a major goal in drug design. Herein, we report the first straight access to indoles from anilines and ethylene glycol by heterogeneous catalysis, based on an acceptorless dehydrogenative condensation, under noninert conditions. In order to achieve high selectivity, a combination of Pt/Al2O3 and ZnO have been found to slowly dehydrogenate ethylene glycol generating, after condensation with the amine and tautomeric equilibrium, the corresponding pyrrole-ring unsubstituted indoles.

Addition reactions of heterocycles—IV

1973

Abstract The reactivity of indole derivatives towards nitrilimines has been studied. Substituents at positions 1, 2 and 3 of the indole ring greatly affect the course of the reaction. 1,3-Dipolar cycloaddition products (3a,8a,dihydropyrazole-[3,4-b]-indole derivatives) and non-cyclic addition products (3-indolyl derivatives) were obtained depending on these substituents. The structures reported were assigned on the basis of satisfactory analytical, spectroscopic and chemical data.

Selektive Synthesen zu 1?-aryl-, 1?-hetaryl-und 1?-alkylsubstituierten 3-Vinylindolen

1987

Selective methods for deriving 1′-aryl-, 1′-indolyl-, 1′-pyrrolyl- and 1′-methyl-substituted 3-vinylindoles2 are described. In all cases the precursors were 3-acylindoles. The new compounds are synthetically useful synthons for annelation of the indole skeleton.

Synthesis of the New Ring System 2-Oxo-[1,4]oxazino[3,2-e]indole, Heteroanalogue of Angelicin

2009

A convenient synthesis of the 2-oxo-[1,4]oxazino[3,2-e]indole ring system, an heteroanalogue of Angelicin, is reported. Our synthetic approach consisted of the annelation of the oxazine ring on the indole moiety using 4-amino-5-hydroxy indoles as building blocks. The antiproliferative activity of the new compounds either in the dark or under UVA irradiation was investigated.

Functionalized 2-azabicyclo[3.3.1]nonanes. IV. synthesis of the indolo[3,2-f]morphan system.

1982

Abstract A short route to the 2-azabicyclo[3.3.1]nonan-7-one system is described. Condensation of 4-piperidones with diethyl 2-oxopropylphosphonate, followed by catalytic hydrogenation furnished the corresponding piperidylpropanones 6 which were cyclized with mercuric acetate in acetic acid to the target target bicyclic ketones 1 . The Fischer indole synthesis from 1 a afforded regioselectively the indole [3,2-f]morphan 2 , a new heteromorphan type.

Zur Reaktion von Indolen mit 1,3-Dithiolenium-Ionen: ein einfacher Zugang zu 3-(1,3-Dithiolan-2-yl)indolen

1986

Reaction of Indoles with 1,3-Dithiolenium Ions: a Simple Access to 3-(1,3-Dithiolan-2-yl)indoles 3-Unsubstituted indoles 1 react regioselectively with 2-methyl- and 2-phenyl-1,3-dithiolenium ions 2 under mild conditions to give the 3-(1,3-dithiolan-2-yl)indoles 4 as protected 3-acylindoles.

2015

Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed.