Uncommon intramolecular palladium-catalyzed cyclization of indole derivatives

A novel synthetic strategy based on the intramolecular palladium-catalyzed oxidative cyclization reaction, allows the formation of C-C bond and the synthesis of β-carbolinones. The reaction has been performed in the presence of catalytic amount of PdCl₂(CH₃CN)₂ and benzoquinone as a reoxidant.     

p-TsOH promoted Fischer indole synthesis of multi-substituted 2-trifluoromethyl indole derivatives

A p-TsOH promoted one-pot synthesis of multi-substituted 2-trifluoromethyl indole derivatives, for instance, 2-trifluoromethyl-3-phenylindoles, 2-trifluoromethyl-indole-3-propanoates, and 2-trifluoromethyl-indole-3-butanoates from reactions of 1,1,1-trifluoro-3-phenylacetone and simply prepared ω-trifluoromethyl substituted δ and ?-ketoesters with arylhydrazines via Fischer indole synthesis has been developed.     

Ring-closing metathesis: novel routes to aromatic heterocycles

Olefin metathesis has been established as an important and general reaction in synthetic organic chemistry. Recently, it has attracted interest as a powerful tool for the construction of aromatic heterocycles. The importance of heteroaromatic motifs in medicinal chemistry and biology, as well as the efficiency and wealth of metathesis transformations, have resulted in significant success in this rapidly developing area.     

A new approach to the synthesis of pentacyclic indole derivatives related to Aspidosperma alkaloids

N-Indolylethyl-2-pyridones bearing appropriate β-dicarbonyl substituents in the 3-position have been cyclised to pentacyclic indoles via spirocyclic indolenines by catalysis with trifluoroacetic anhydride.     

Copper-catalyzed domino intramolecular cyclization: a facile and efficient approach to polycyclic indole derivatives

A mild and efficient Cu(2)O-catalyzed domino intramolecular C-N coupling/C-Y (Y = O, S, N) bond formation was successfully achieved. Thus oxazino[3,2-a]indole, thiazino[3,2-a]indole and indolo[2,1-b]quinazoline derivatives were facilely assembled from readily accessible gem-dibromovinyl systems. The protocol is general and practical, affording a variety of the indole-incorporated products in good to excellent yields even under air atmosphere.     

A new approach to the synthesis of pyrrolo[1,2-a]indole derivatives

Reactions of 2-(3,3-diamino-2-cyanoprop-2-enylidene)indolin-3-ones with amide acetals afforded derivatives of 3-aminomethyleneamino-2-cyano-9-oxo-9H-pyrrolo[1,2-a]indole and 3-amino-2-cyano-9-oxo-9H-pyrrolo[1,2-a]indole. The rate and pathway of the reaction depend on the reagents and solvents. The formation schemes for the compounds obtained were proposed. Their structures were proven by IR and ¹H NMR spectroscopy and mass spectrometry and confirmed by independent syntheses. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2186–2192, December, 2006.     

Gold-catalyzed heteroannulation and allyl migration: synthesis of highly functionalized indole derivatives

Highly substituted indole derivatives have been prepared in good to excellent yields by a novel gold-catalyzed cyclization accompanied by [3,3]-migration of the allyl strategy. We have been able to introduce an allyl group at the C1 position of pyrano[3,2-e]indol-6(7H)-one and pyrrolo[3,2-f]quinolin-7(6H)-one moieties that provide a scope for further transformation.     

Synthesis,characterization, and biological evaluation of indole aldehydes containing N-benzyl moiety

Abstract

The present study describes the synthesis, characterization and biological evaluation of N-benzyl indole aldehydes. The biological activities of the newly synthesized compounds were examined by investigating their antioxidant and anti-inflammatory activities. The potential of these compounds as an antioxidant was determined by 2,2-diphenylpicrylhydrazyl, Nitric oxide, Superoxide, peroxide radical scavenging methods. We found that aldehydes 4a, 4b, 4c, and 4e and shows promising in vitro DPPH scavenging antioxidant activity while aldehyde 4b and 4e show good in vitro anti-inflammatory activity.     

Photoaddition of N-substituted piperazines to C60: an efficient approach to the synthesis of water-soluble fullerene derivatives

An oxidative radical photoaddition of mono N-substituted piperazines to [60]fullerene was systematically investigated. Reactions of C60 with piperazines bearing bulky electron-withdrawing groups (2-pyridyl, 2-pyrimidinyl) were found to be the most selective and yielded C60(amine)4O as major products along with small amounts of C60(amine)2. In contrast, interactions of fullerene with N-methylpiperazine and N-(tert-butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions. Tetraaminofullerene derivative C60(N-(2-pyridyl)piperazine)4O was found to react readily with organic and inorganic acids to yield highly water-soluble salts (solubility approximately 150 mg mL(-1)). In contrast, C60(N-(2-pyrimidinyl)piperazine)4O undergoes hydrolysis under the same conditions and results in a complex mixture of compounds with an average composition of C60(N-(2-pyrimidinyl)piperazine)2(OH)2O. Radical photoaddition of N-(2-pyridyl)piperazine to fullerene derivatives can be used as a facile route for their transformation into water-soluble compounds. Two model fullerene cycloadducts (a methanofullerene and a pyrrolidinofullerene) were easily converted into mixtures of regioisomers of A=C60(N-(2-pyridyl)piperazine)4O (A=cyclic addend) that give highly water-soluble salts under acid treatment.     

The Photochemistry of Acetone: The Primary Decomposition of Acetone and Biacetyl Yields

In the photolysis of acetone at 265nm at 27°C the quantum yield of biacetyl has been determined to be 0.34 and the primary decomposition yield is evaluated to be about 0.68. The fraction of triplet acetone decomposed into methyl and acetyl radicals is estimated to be 0.14 at 313nm. The acetyl radicals undergo reaction to form biacetyl 50 times faster than decomposition to methyl radicals and carbon monoxide.     

Synthesis of novel tricyclic isoindole derivatives

Novel 3-methylene-2,5-dioxo-3H,9bH-oxazolo[2,3-a]isoindoles were prepared from the thermolysis of (3R,9bS)-5-oxo-2,3,5,9b-tetrahydrothiazolo[2,3-a]isoindole-3-carboxylic acids in acetic anhydride. The structure of 3-methylene-2,5-dioxo-3H,9bH-oxazolo[2,3-a]isoindole 6a was determined by X-ray crystallography.     

F-Tag Induced Acyl Shift in the Photochemical Cyclization of o-Alkynylated N-Alkyl-N-acylamides to Indoles**

A photochemical cyclization of F-tagged, o-alkynylated N-alkylamides to indoles catalyzed by [Ir(dF(CF₃)ppy)₂(dtbpy)]PF₆ is presented. This straightforward and efficient reaction involves an intramolecular rearrangement due to the presence of an electron withdrawing group in the acyl moiety and is the first example of photochemically induced 1,3-acyl shift in the cyclization towards 3-acylindoles. A four-step reaction sequence including the photoreaction as a key step to the desired indoles has been developed and optimized. The compatibility of differently substituted F-tagged precursors with the photocyclization step was investigated and the robustness of this step towards modifications could be shown. In total, 16 so far unknown derivatives with diverse modifications in positions N1 and C2, bearing a pentadecafluorooctanoyl moiety as F-tag, were synthesized in very good yields and fully characterized.     

Synthesis and Photochemistry of Diphenylchlorin and Diphenylbacteriochlorin

5, 15-Diphenylporphyrin (DPP), a novel porphyrin model compound, was always inaccessible in quantities suitable for study1 because the difficulty of synthesis. So that the characteristic of this molecule had not been explored until a novel method developed for the preparation of DPP recently2. Therefore it will be possible for the synthesis of DPP-based photosensitizers, and investigation of their photodynamic properties. Here we reported the synthesis of novel photosensitizers 5, 15-diphe…     

Dimeric indole alkaloids of a new type a synthetic approach to the ervafoline series

A synthetic approach towards the dimeric ervafoline indole alkaloids has been achieved $\text{via}$ a route inspired from a biogenetic hypothesis.