Search results for "Indole"

Site-specific halloysite functionalization by polydopamine: A new synthetic route for potential near infrared-activated delivery system

2022

Abstract Halloysite nanotubes (HNTs) represent a versatile core structure for the design of functional nanosystems of biomedical interest. However, the development of selective methodologies for the site-controlled functionalization of the nanotubes at specific sites is not an easy task. This study aims to accomplish a procedure for the site-selective/specific, “pin-point”, functionalization of HNTs with polydopamine (HNTs@PDA). This goal was achieved, at pH 6.5, by exploiting the basicity of ZnO nanoparticles anchored on the HNTs external surface (HNTs@ZnO) to induce a punctual polydopamine polymerization and coating. The morphology and the chemical composition of the nanomaterial was demo…

NUCLEOPHILIC SUBSTITUTIONS IN ISOINDOLE SERIES AS VALUABLE TOOL TO SYNTHESIZE DERIVATIVES WITH ANTITUMOR ACTIVITY

2009

ISOXAZOLO[5,4-E]ISOINDOLE: A NEW RING SYSTEM WITH POTETIAL PHOTOBIOLOGICAL PROPERTIES

2008

Convenient synthesis of pyrrolo[3,4-g]indazole

2013

Abstract The synthesis of a novel class of tetrahydropyrrolo[3,4-g]indazoles is reported, by annelation of the pyrazole ring on the isoindole moiety by means of 5-hydroxymethylene tetrahydroisoindole-4-ones key intermediates, with good regioselectivity. Dihydroderivatives were also obtained by oxidation with DDQ of the corresponding tetrahydropyrrolo[3,4-g]indazoles. The growth inhibitory effect was evaluated at the National Cancer Institute of Bethesda and some derivatives showed modest activity.

Structure and Synthesis of a New Indole Alkaloid, 19 (S)-Hydroxy-Nb-methylraumacline, Obtained by the Biotransformation of Ajmaline in Plant Cell Cul…

1992

Abstract From the plant cell suspension cultures of Tauwolfia serpentina Benth ., which were cultivated in the alkaloid-production medium after feeding of ajmaline (1) , a new indole alkaloid 19- ( S )-hydroxy- N b -methylraumacline ( 4 ) was isolated. The structure of 4 first elucidated by spectroscopic analysis was determined by the chemical synthesis from ajmaline ( 1 ).

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.