Dataset Information

Copper-Promoted Regioselective Intermolecular Diamination of Ynamides: Synthesis of Imidazo[1,2-a]pyridines.

ABSTRACT: A facile access to 3-heterosubstituted (3-oxazolidinonyl/indolyl/phenoxy) imidazo[1,2-a]pyridines from readily available 2-aminopyridines and electron-rich (internally activated) alkynes like ynamides/ynamines/ynol ethers is achieved via Cu(OTf)2-mediated intermolecular diamination under aerobic conditions. The reaction is highly regioselective, owing to internal electron bias, and thus led to a single regioisomer with heterosubstitution at C3.

SUBMITTER: Dwivedi V

PROVIDER: S-EPMC6641143 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Copper-Promoted Regioselective Intermolecular Diamination of Ynamides: Synthesis of Imidazo[1,2-a]pyridines.

Dwivedi Vikas V Kumar Ravi R Sharma Kavita K Sridhar Balasubramanian B Reddy Maddi Sridhar MS

ACS omega 20170619 6

A facile access to 3-heterosubstituted (3-oxazolidinonyl/indolyl/phenoxy) imidazo[1,2-a]pyridines from readily available 2-aminopyridines and electron-rich (internally activated) alkynes like ynamides/ynamines/ynol ethers is achieved via Cu(OTf)2-mediated intermolecular diamination under aerobic conditions. The reaction is highly regioselective, owing to internal electron bias, and thus led to a single regioisomer with heterosubstitution at C3. ...[more]

PMID: 31457615

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Project description:Background?-Bromination of the side chain of aromatic ketones using NBS in the presence of p-toluenesulfonic acid (p-TsOH) in acetonitrile is very common. However, regioselective bromination of bis and tris(?-bromoacetophenones) with NBS in the presence of p-TsOH in acetonitrile under microwave irradiation is quite novel. The bis- and tris(?-bromoacetophenones) are used in synthesis of bis and tris(heterocycles). bis(heterocycles) have received a great deal of attention, because many biologically active natural and synthetic products have molecular symmetry. The use of the pressurized microwave irradiation is very advantageous to many syntheses and provide a large rate enhancement.ResultsBis and tris(?-bromoacetophenones) were obtained as single monobrominated derivatives in a shorter time than the conventional conditions. The results clearly demonstrate the better reactivity and selectivity of NBS/p-TsOH/CH3CN as a brominating mixture under microwave conditions. The reaction of bis and tris(?-bromoacetophenone) with 2-aminopyridine and 2-aminopyrimidine proceeded smoothly in a mixture of anhydrous ethanol and DMF under reflux or using 300 W/105°C/ 20 min microwave irradiation conditions to afford the corresponding bis(imidazo[1,2-a]pyridine), bis(imidazo[1,2-a]pyrimidine) and tris(imidazo[1,2-a]pyridine) derivatives in moderate to excellent yields. The carbonyl analogue of the targeted bis(imidazopyridines) could be synthesized by the reaction of N,N-dimethyl-N'-(pyridin-2-yl)formimidamide with bis(?-bromoacetophenone) in refluxing ethanol. The structures of the newly synthesized compounds were confirmed by their spectral data as well as their elemental analyses.ConclusionIn conclusion, selective ?-bromination of bis- and tris(acetophenones) has been accomplished efficiently utilizing NBS/p-TsOH/CH3CN under microwave irradiation. In addition, a facile synthesis of novel series of bis- and tris(imidazopyridine) and bis(imidazopyrimidine) derivatives.

Dataset Information

Copper-Promoted Regioselective Intermolecular Diamination of Ynamides: Synthesis of Imidazo[1,2-a]pyridines.

Publications

Copper-Promoted Regioselective Intermolecular Diamination of Ynamides: Synthesis of Imidazo[1,2-<i>a</i>]pyridines.

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