Non-imidazole heterocyclic histamine H3 receptor antagonists

Metal-Free Construction of Multisubstituted Indolizines via Intramolecular Amination of Allylic Alcohols

An intramolecular amination of allylic alcohols is developed as an efficient and general access to biologically important multisubstituted indolizines and their variants. Two metal-free synthetic platforms including using aqueous hydrochloric acid solution as the solvent and p-toluenesulfonic acid as the catalyst have been established, enabling the divergent synthesis of these valuable compounds in high yields.

Electro-Oxidative sp3 C-H Bond Functionalization and Annulation Cascade: Synthesis of Novel Heterocyclic Substituted Indolizines

Indolizine derivatives are prevalent in many synthetic intermediates, pharmaceuticals, and organic materials. Herein, we report a novel electro-oxidative cascade cyclization reaction that uses electricity as the primary energy input to promote the reaction, leading to a series of heterocyclic substituted indolizine derivatives under exogenous-oxidant-free conditions. It is noteworthy that this electrochemical method provides a novel strategy for generating heterocyclic diversity of quinazolinones and quinolines on indolizines. In addition, the sole byproduct in the reaction was molecular hydrogen.

Efficient synthesis of novel indolizine C-nucleoside analogues via coupling of sugar alkynes, pyridines and α-bromo carbonyl compounds in one pot

The synthesis of novel indolizine C-nucleoside analogues has been achieved by the three-component coupling reaction of sugar alkynes, pyridines and α-bromo carbonyl compounds in one pot. The corresponding products are obtained in good to excellent yields. 49 examples have been given. The synthetic method is convenient, practical and efficient. It is suitable for various substrates including structurally diversified sugar alkynes with sensitive groups. The sugar alkynes include pyranosides, furanosides, and acyclic sugars. A plausible mechanism for the formation of indolizine C-nucleoside analogues has been elucidated.

Synthesis of Novel bis-spirooxindoles Catalyzed by Magnetic Cobalt Ferrite Encapsulated MCM-41@MgO as a Solid Base

AIMS AND OBJECTIVE

Synthesis of novel bis-spirooxindoles was carried out from isatins, two equivalents of malononitrile, and various derivatives of cyclohexanones.

BACKGROUND

A facile one-pot and four-component reaction was investigated for the synthesis of novel bisspirooxindoles from different derivatives of isatins, two equivalents of malononitrile and various derivatives of cyclohexanone in the presence of magnetic CoFe2O4@MCM-41@MgO NPS catalyst under mild conditions.

MATERIALS AND METHODS

Firstly, the magnetic CoFe2O4@MCM-41@MgO was prepared in three steps. Afterwards, the CoFe2O4@MCM-41@MgO was used as a base catalyst for the one-pot synthesis of bisspirooxindoles.

RESULTS AND DISCUSSION

The procedure exhibited several benefits, an excellent yield of products, short reaction times, reusability, and recyclability of the nanocatalyst.

CONCLUSION

The structure of nanocatalyst was recognized by FT-IR, XRD, VSM, SEM, BET, and EDX techniques, and the structure of the organic products was determined by melting point, FT-IR, 1H NMR, 13C NMR, Mass spectra, and C.H.N analyses.

Brønsted-acid-catalyzed selective Friedel-Crafts monoalkylation of isatins with indolizines in water

The controlled mono-addition of indolizines to isatins under very mild conditions is described. The reaction occurs in water using diphenylphosphate as the catalyst, which is dramatically accelerated by surfactant addition. 3-Hydroxy-3-indolizinyl-2-oxindole scaffolds were synthesized in up to >99% yield. Notably, in organic solvents only bis-addition products were observed.

Synthesis of functionalized indolizines via gold(i)-catalyzed intramolecular hydroarylation/aromatization of pyrrole-ynes

A gold-catalyzed intramolecular hydroarylation/aromatization of pyrrole-ynes has been developed. This method provides a concise and straightforward route to functionalized indolizines through the construction of the pyridine ring of indolizines and also allows elaboration of its pyrrole moiety with or without functional groups. In addition, a wide variety of functional groups, such as aryl, alkenyl, alkynyl, pyridyl or thienyl groups, can be easily incorporated into the pyridine unit of the indolizine products under mild conditions. The utility of the indolizine products was demonstrated by their efficient transformations into various C3-functionalized indolizine derivatives.

Synthesis of 7-cyanoindolizine derivatives via a tandem reaction

A series of 2-substituted and 2,3-disubstituted 5-cyanoindolizine derivatives were conveniently synthesized by a one-pot tandem reaction under mild conditions in moderate yields. The reaction mechanism was proposed.

Transition-metal-free synthesis of indolizines via [3 + 2]-annulation from α-bromoenals and 2-substituted azaarenes

A transition-metal-free “one-pot” synthetic approach for the synthesis of indolizines from α-bromo-substituted enals and simple 2-substituted azaarenes has been developed.

Greener synthesis of indolizine analogues using water as a base and solvent: study for larvicidal activity against Anopheles arabiensis

Greener synthesis of a series of novel indolizine analogues have been achieved by the cyclization of aromatic cycloimmonium ylides with electron-deficient alkynes in the presence of water as the base and solvent at 80 °C. Yield of the title compounds was good and reactions performed were eco-friendly. The structures of these newly synthesized compounds have been confirmed by spectroscopic techniques such as FTIR, NMR, LC-MS, and elemental analysis. Characterized title compounds were evaluated for larvicidal activity against Anopheles arabiensis by standard WHO larvicidal assay using Temefos as standard at 4 μg/mL. Title compounds 2e, 2f, and 2g emerged as promising larvicidal agents.

Synthesis and crystal structures of three novel benzimidazole/benzoindolizine hybrids

Three benzoindolizine derivatives, 1, 2, and 3, were obtained via 1,3-dipolar cycloaddition. The reaction of 1-(2′-benzimidazolylmethyl)isoquinolinium ylides with dimethyl acetylenedicarboxylate gave a mixture of pyrrolo[2,1-a]isoquinoline-1,2-dicarboxylate (1) and 1,10b-dihydropyrrolo[2,1-a]isoquinoline-1,2-dicarboxylate (2) derivatives containing a benzimidazole moiety. The reaction of this isoquinolinium N-ylide with dimethyl maleate gave an unexpected 2,3-dihydropyrrolo[2,1-a]isoquinoline-1,2-dicarboxylate (3). The structures of all reported compounds have been examined by X-ray crystallography, mass spectrometry, and NMR spectroscopy.

Synthesis of substituted indolizines via radical oxidative decarboxylative annulation of 2-(pyridin-2-yl)acetate derivatives with α,β-unsaturated carboxylic acids

A copper mediated radical oxidative annulation of 2-(pyridin-2-yl)acetate derivatives with α,β-unsaturated carboxylic acids is developed.

Recent advances in the synthesis of indolizines and their π-expanded analogues

Synthesis of indolizines developed during the last decade is reviewed, with special emphasis given to densely functionalized architectures, breakthrough strategies, compounds bearing electron-donating and electron-withdrawing substituents and π-expanded systems.

Multicomponent Strategy to Pyrazolo[3,4-e]indolizine Derivatives under Microwave Irradiation

A simple and efficient one-pot construction of pyrazolo[3,4-e]indolizine derivatives via a diethylamine-catalyzed three-component domino reaction of arylglyoxals, cyclic 1,3-diones, and 5-aminopyrazoles under microwave irradiation is described. In this one-pot transformation, seven bonds and two new rings are efficiently formed. This synthesis was confirmed to follow the group-assisted-purification (GAP) chemistry process, which can avoid traditional recrystallization or chromatography purification methods.

A facile approach for the synthesis of 1,3-di- and 1,2,3-tri-substituted indolizines

A convenient synthesis of 1,3-di- and 1,2,3-tri-substituted indolizines involving the multicomponent reaction of pyridinium salt (or quinolinium salt), olefine acid, and 1,2-dichloroethane has been achieved. The process proceeds smoothly in moderate to high yields.

The synthesis, characterization and optical properties of novel 2-acyl 6-arylindolizines

A series of novel 2-acyl-6-aryl substituted indolizine derivatives was synthesized by a novel tandem reaction between 4-acyl-pyrrole-2-carbaldehyde derivatives and ethyl 4-bromo-3-arylbut-2-enoate under mild conditions. The compounds were characterized using IR, (1)H NMR (13)C NMR and HRMS. The crystal structure of 7a was determined using single crystal X-ray crystallography. The absorption results showed that compounds 7a-e presented their absorption maxima at ca. 270 nm, while compounds 7f and 7g with a larger conjugation system exhibited red-shifted absorption character (ca. 280 nm). Fluorescence spectra revealed that these compounds exhibited blue fluorescence (434-456 nm) in dilute solutions and showed quantum yields of fluorescence between 0.02 and 0.39 in dichloromethane.

Palladium-catalyzed direct and regioselective C–H acyloxylation of indolizines

A direct and highly regioselective C1-acyloxylation of indolizines was developed via palladium-catalyzed C–H functionalization. In this reaction, the regioselectivity was achieved in the absence of a directing group.

An efficient synthesis of pyrido[1,2-a]indoles through aza-Nazarov type cyclization

Transition metal free Brønsted acid mediated synthesis of pyrido[1,2-a]indole scaffolds has been developed through aza-Nazarov type cyclization of readily available diaryl(2-pyridyl)methanol using formic acid for the synthesis of biologically and medicinally important pyrido[1,2-a]indole, indolo[1,2-a]quinoline and pyrimido[1,2-a]indole derivatives.

Silver-Mediated Synthesis of Indolizines via Oxidative C-H functionalization and 5- endo-dig cyclization

An efficient strategy for the synthesis of indolizines from readily available starting materials via oxidative C-H functionalization and 5-endo-dig cyclization in one step has been demonstrated. This protocol represents wide substrate scope, high functional group tolerance and selectivity. The structure of the product was confirmed by the X-ray crystallographic studies. The Ag₂CO₃ required of this tandem reaction can be recycled and reused after undergoing oxidative reaction.

A direct method for the synthesis of indolizine derivatives from easily available aromatic ketones, pyridines, and acrylonitrile derivatives

A concise and efficient strategy has been proposed to synthesize indolizine derivatives from easily available aryl or heteroaryl methyl ketones, pyridines, and acrylonitriles. The mechanistic pathway involved the integration of iodination, pyridinium ylide synthesis, and 1,3-dipolar cycloaddition. The protocols were found to be highly efficient in terms of high yields, operational simplicity, mild reaction conditions, and easy workup. This method has provided an important supplement for the synthesis of indolizine derivatives via a novel tandem synthesis.

Copper(II)-catalyzed synthesis of benzo[f]pyrido[1,2-a]indole-6,11-dione derivatives via naphthoquinone difunctionalization reaction

Benzo[f]pyrido[1,2-a]indole-6,11-diones have been synthesized in high yields by copper(II)-catalyzed three-component reactions of acyl bromide, 1,4-naphthoquinone, and pyridine (or isoquinoline) via sp(2)-C-H difunctionalization of naphthoquinone followed by intramolecular cyclization and oxidative aromatization. In an attempt to expand the reaction scope and to help clarify the reaction mechanism, 1,3-dicarbonyl compounds are used in place of acyl bromides to take part in this reaction, and the benzo[f]pyrido[1,2-a]indole-6,11-diones derivatives are also obtained in excellent yields.

Amberlite-IRA-402 (OH) ion exchange resin mediated synthesis of indolizines, pyrrolo [1,2-a] quinolines and isoquinolines: antibacterial and antifungal evaluation of the products

A number of indolizines and pyrrolo[1,2-a]quinolines/isoquinolines were prepared from phenacyl pyridinium, quinolinium and isoquinolinium salts derived from the reaction of the heterocycles with 2-bromo acetophenone with alkynes and alkenes using amberlite-IRA-402 (OH) ion exchange resin as the base. Antibacterial and antifungal studies were carried out against thirteen bacterial and four fungal strains, which revealed that three derivatives (4a, 4b, 7a) out of fifteen are effective against all the thirteen strains and one derivative, 10, showed dual antibactericidal and antifungal efficacy.