Ultrasonic-mediated catalyst-free rapid protocol for the multicomponent synthesis of dihydroquinoline derivatives in aqueous media

Abstract

Catalyst-free multicomponent protocol for the condensation of malononitrile, 2-naphthol/resorcinol, aldehydes, and ammonium acetate in aqueous medium under ultrasound irradiation at 60 o C afforded a wide range of valuable dihydroquinolines in high yields (90-97%) with short reaction times (60-90 min). This approach offers vital improvements for the synthesis of target compounds with regard to yield of products, simplicity in operation, utilization of water as solvent, and green aspects by avoiding the catalysts or solvents.

Ultrasound-assisted one-pot multi-component synthesis of 2-pyrrolidinon-3-olates catalyzed by Co3O4@SiO2core–shell nanocomposite

“…Furthermore, MCRs are easy to perform, inexpensive, quick, energy efficient and experimental procedures are relatively simple (1). Recently, the application of ultrasonic irradiation in chemical syntheses has received much attention (2)(3)(4)(5). On the other hand, designing MCRs under ultrasonic irradiation is another attractive area in synthetic organic chemistry.…”

Organocatalytic clean synthesis of densely functionalized 4H-pyrans by bifunctional tetraethylammonium 2-(carbamoyl)benzoate using ball milling technique under mild conditions

“…These factors are especially important in industry. On the other hand, multicomponent reactions (MCRs), defined as any process in which three or more reactants combine in one pot to generate a product containing all or most atoms of the starting materials, are highly atom efficient (5)(6)(7)(8). Thus, an ideal MCR involves the simultaneous addition of reactants, catalyst, or reagents at the beginning of the reaction and requires that all reactants couple in an exclusive ordered mode under the same reaction conditions (5)(6)(7)(8).…”

“…On the other hand, multicomponent reactions (MCRs), defined as any process in which three or more reactants combine in one pot to generate a product containing all or most atoms of the starting materials, are highly atom efficient (5)(6)(7)(8). Thus, an ideal MCR involves the simultaneous addition of reactants, catalyst, or reagents at the beginning of the reaction and requires that all reactants couple in an exclusive ordered mode under the same reaction conditions (5)(6)(7)(8). Their superior atom economy, resulting in substantial minimization of waste, labour, time, and cost as well as high efficiency, mild conditions, high convergence, and their general compatibility with green solvents, would justify a central place in the toolbox of green synthetic methodologies (5)(6)(7)(8).…”

“…Thus, an ideal MCR involves the simultaneous addition of reactants, catalyst, or reagents at the beginning of the reaction and requires that all reactants couple in an exclusive ordered mode under the same reaction conditions (5)(6)(7)(8). Their superior atom economy, resulting in substantial minimization of waste, labour, time, and cost as well as high efficiency, mild conditions, high convergence, and their general compatibility with green solvents, would justify a central place in the toolbox of green synthetic methodologies (5)(6)(7)(8). Therefore, academic and industrial research groups have increasingly focused on the use of MCRs for synthesizing a broad range of products especially important heterocyclic compounds such as 4H-pyran derivatives nowadays (9,(10)(11)(12).…”

One-pot, clean and energy efficient synthesis of dibenzo[b,f][1,4]oxazepine derivatives promoted by ultrasound

“…Some important therapeutically active dibenzoxazepines seems, development of a clean, mild, fast, inexpensive, and versatile method for the synthesis of the dibenzo[b,f] [1,4]oxazepines is necessary. Nowadays, the concept of speeding up the chemical transformations by ultrasound irradiation has created a lot of great interest in chemistry [19][20][21][22][23][24][25][26][27][28].…”