Exploration of copper and amine-free Sonogashira cross coupling reactions of 2-halo-3-alkyl imidazo[4,5-b]pyridines using tetrabutyl ammonium acetate as an activator under microwave enhanced conditions

Sajith, Ayyiliath M.; Muralidharan, A.

doi:10.1016/j.tetlet.2012.07.028

Cited by 50 publications

(24 citation statements)

References 21 publications

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“…The TBAB acted as an ionic medium and was advantageous over VOCs, the TBA-salts also used in several C-C bond-forming transformations. 46,47,50,52,[65][66][67] Encouraged by this result, further screened with various tetrabutylammonium-salts, for instances, TMAB (tetra-methylammonium bromide), TEAB (tetraethylammonium bromide), TBAA (tetra-butylammonium acetate), TBAI (tetra-butylammonium iodide) at 80 C carried out, here 4ab was obtained in good to excellent yields up to 87% ( Table 1, entries [22][23][24][25]. Among the tested TBA-salts, TBAA with 87% yield of desired product emerged out as the best-optimized condition ( Table 1, entry 24).…”

Section: Chemistrymentioning

confidence: 99%

“…Interestingly, the TBAA (tetrabutylammonium acetate) acted as a reaction medium instead of VOCs, in several C-C bond forming reactions. 46,47,[49][50][51][52][53][54] Likewise, diabetes mellitus (DM) type-2, a chronic metabolic disorder, was characterized by high blood sugar, insulin resistance, and secretion. The common symptoms were continual urination, increased hunger, and thirst, tiredness, and unexpected weight loss, and so forth.…”

Section: Introductionmentioning

confidence: 99%

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Cu/TEMPO catalyzed dehydrogenative 1,3-dipolar cycloaddition in the synthesis of spirooxindoles as potential antidiabetic agents

et al. 2020

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A series of spiro-[indoline-3,3 0 -pyrrolizin/pyrrolidin]-2-ones, 4, 5 and 6 were synthesized in a sequential manner from Cu-TEMPO catalyzed dehydrogenation of alkylated ketones, 1 followed by 1,3-dipolar cycloaddition of azomethine ylides via decarboxylative condensation of isatin, 2 and L-proline/sarcosine, 3 in high regioselectivities and yields. The detailed mechanistic studies were performed to identify the reaction intermediates, which revealed that the reaction proceeds via dehydrogenative cycloaddition.Additionally, the regio and stereochemistry of the synthesized derivatives were affirmed by 2D NMR spectroscopic studies. The synthesized derivatives were explored further with molecular docking, in vitro antioxidant, and anti-diabetic activities. † Electronic supplementary information (ESI) available: Copies of NMR, HRMS and FT-IR spectra of all compounds and 2D-NMR spectra for selected compounds. See

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Section: Chemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cu/TEMPO catalyzed dehydrogenative 1,3-dipolar cycloaddition in the synthesis of spirooxindoles as potential antidiabetic agents

et al. 2020

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“…The same authors described the synthesis of imidazo[4,5- b ]pyridines in the reaction with 1,1′-carbonyldiimidazole (CDI) and then with phosphoryl chloride or with formic acid followed by halogenation with carbon tetrabromide or N -iodosuccinimide (NIS) ( Scheme 15 ) [ 93 ].…”

Section: Synthetic Routes To Imidazo[45- B ]Pymentioning

confidence: 99%

Pharmacological Potential and Synthetic Approaches of Imidazo[4,5-b]pyridine and Imidazo[4,5-c]pyridine Derivatives

2017

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The structural resemblance between the fused imidazopyridine heterocyclic ring system and purines has prompted biological investigations to assess their potential therapeutic significance. They are known to play a crucial role in numerous disease conditions. The discovery of their first bioactivity as GABAA receptor positive allosteric modulators divulged their medicinal potential. Proton pump inhibitors, aromatase inhibitors, and NSAIDs were also found in this chemical group. Imidazopyridines have the ability to influence many cellular pathways necessary for the proper functioning of cancerous cells, pathogens, components of the immune system, enzymes involved in carbohydrate metabolism, etc. The collective results of biochemical and biophysical properties foregrounded their medicinal significance in central nervous system, digestive system, cancer, inflammation, etc. In recent years, new preparative methods for the synthesis of imidazopyridines using various catalysts have been described. The present manuscript to the best of our knowledge is the complete compilation on the synthesis and medicinal aspects of imidazo[4,5-b]pyridines and imidazo[4,5-c]pyridines reported from the year 2000 to date, including structure–activity relationships.

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“…However, the procedures were far from being sustainable, since it was necessary to use phosphines, organic solvents, copper compounds, and a base. Instead, the Sonogashira reaction was made more eco-friendly when tetrabutylammonium acetate was introduced as an activator [82] in a copper-free system, with complete substrate disappearance within 15 min (Scheme 22). An unusual Heck-type alkenylation was obtained directly from aryl alcohols instead of alkenes, in a one-pot reaction that was assisted by ILs and MW [79].…”

Section: Scheme 14mentioning

confidence: 99%

“…Scheme 22. MW-irradiated Pd-catalyzed, amine and copper-free Sonogashira reaction with ammonium salt activator [82].…”

Section: Scheme 14mentioning

confidence: 99%

The Beneficial Sinergy of MW Irradiation and Ionic Liquids in Catalysis of Organic Reactions

et al. 2017

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Abstract:The quest for sustainable processes is becoming more and more important, with catalysis playing a major role in improving atom economy and reducing waste. Organic syntheses with less need of protecting/de-protecting steps are highly desirable. The combination of microwave irradiation, as energy source, with ionic liquids, as both solvents and catalysts, offered interesting solutions in recent years. The literature data of the last 15 years concerning selected reactions are presented, highlighting the importance of microwave (MW) technology coupled with ionic liquids.

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Exploration of copper and amine-free Sonogashira cross coupling reactions of 2-halo-3-alkyl imidazo[4,5-b]pyridines using tetrabutyl ammonium acetate as an activator under microwave enhanced conditions

Cited by 50 publications

References 21 publications

Cu/TEMPO catalyzed dehydrogenative 1,3-dipolar cycloaddition in the synthesis of spirooxindoles as potential antidiabetic agents

Cu/TEMPO catalyzed dehydrogenative 1,3-dipolar cycloaddition in the synthesis of spirooxindoles as potential antidiabetic agents

Pharmacological Potential and Synthetic Approaches of Imidazo[4,5-b]pyridine and Imidazo[4,5-c]pyridine Derivatives

The Beneficial Sinergy of MW Irradiation and Ionic Liquids in Catalysis of Organic Reactions

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