Expeditious one-pot multicomponent microwave-assisted green synthesis of substituted 2-phenyl Quinoxaline and 7-bromo-3-(4-ethylphenyl) pyrido[2,3-b]pyrazine in water–PEG and water–ethanol

<p>An eco-friendly, expeditious one-pot multicomponent synthesis of substituted 2-phenyl quinoxaline and 7-bromo-3-(4-ethylphenyl) pyrido[2,3-<i>b</i>]pyrazine <b>4a–k</b> in water–ethanol from easily available starting materials as acetophenone <b>1</b>, succinamide <b>2</b>, aromatic amine <b>3</b>, <i>in situ</i>-generated α-iodo acetophenone from acetophenone, succinamide and catalyzed by silver iodide in combination with green solvent polyethylene glycol-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of products in very short time of reaction by avoiding the use of lacrimatic α-chloro and α-bromocarbonyl compounds, volatile, toxic organic hazardous solvents, and reagents is the advantage of this research work. The final products were confirmed by their characterization data such as FTIR, ¹H NMR, ¹³C NMR, Mass, HRMS and were compared with its reported method.</p

Greener approach: Ionic liquid [Et₃NH][HSO₄]-catalyzed multicomponent synthesis of 4-arylidene-2-phenyl-5(4<i>H</i>)oxazolones under solvent-free condition

<p>We have developed simple, greener, safer multicomponent synthesis series of 4-arylidene-2-phenyl-5(4<i>H</i>) oxazolones <b>4(a-r)</b> catalyzed by Bronsted acid ionic liquid as triethylammonium hydrogen sulfate [Et₃NH][HSO₄] and catalytic amount of acetic anhydride and sodium acetate with excellent yields (90–99%). The protocol offers economical, environmentally benign, solvent-free conditions, and recycle–reuse of the catalyst and easily available starting as benzoyl chloride <b>1</b>, amino acid <b>2</b> and a variety of aldehydes <b>3</b>. The cyclization followed by condensation of benzoyl chloride, amino acid, and a variety of aldehydes catalyzed by ILs [Et₃NH][HSO₄] and catalytic amount of acetic anhydride and sodium acetate. The final products were confirmed by their characterization data such as FTIR, ¹H-NMR, ¹³C-NMR, Mass, high-resolution mass spectra and were compared with its reported method.</p

Rapid and efficient one-pot microwave-assisted synthesis of 2-phenylimidazo[1,2-<i>a</i>]pyridines and 2-phenylimidazo[1,2-<i>a</i>]quinoline in water–PEG-400

<p>An effective, expeditious, environmentally benign one-pot synthesis of 2-phenylimidazo[1,2-<i>a</i>]pyridines and 2-phenylimidazo[1,2-<i>a</i>]quinoline from easily available starting materials as aromatic carbonyl compound, 2-amino pyridine, succinamide, and <i>in situ</i> generated α-iodo acetophenone in combination with green solvent PEG-400 and water (2:1) under microwave irradiation. The newly developed protocol with excellent yield of product in very short time of reaction by avoiding the use of lachrymatric α-chloro and α-bromocarbonyl compounds, volatile, toxic organic and hazardous solvents, reagents is the advantage of this research work. The final products were confirmed by their characterization data such as ¹H NMR, ¹³C NMR, high resolution mass spectrometry (HRMS) and were compared with its reported method.</p