An efficient microwave‐assisted synthesis of 3,5‐unsubstituted 4‐substituted‐6‐aryl‐3,4‐dihydropyridin‐2(1H)‐ones derivatives

Abstract

Small libraries of 3,5‐unsubstituted 4‐substituted‐6‐aryl‐3,4‐dihydropyridin‐2(1H)‐ones derivatives were synthesized from the condensation‐products of aldehydes with Meldrum's acid, aromatic ketones and ammonium acetate using acetic acid as energy transferring‐agent under microwave irradiation without catalyst. This method has the advantages of excellent yields (65‐90%), short reaction time (5‐10 min) and being environmentally friendly. It aimed to provide new series of potential biologically active compounds for biomedical screening.

Phosphonic Acid Functionalized Ordered Mesoporous Material: A New and Ecofriendly Catalyst for One-Pot Multicomponent Biginelli Reaction under Solvent-Free Conditions

“…One-pot multicomponent reactions (MCRs) have attracted huge research interest in synthetic organic, medicinal, and materials chemistry over the past 2 decades because of the high degree of atom economy and construction of the complex target molecules/frameworks in a convergent way. − The Biginelli reaction is one of the most important MCRs that offer an efficient route to produce multifunctionalized 3,4-dihydropyridin-2-1 H -(ones)/3,4-dihydropyridin-2-1 H -(thiones) (DHPMs) and related heterocyclic compounds through the cycloaddition of aldehyde, 1,3-ketoesters, and urea or thiourea. − Polyfunctionalized DHPMs have found increasing applications for the synthesis of biologically relevant substances exhibiting a wide range of important pharmacological properties, including mitotic kinesin inhibition, calcium channel modulation, and α 1a -adrenergicreceptor antagonism. − In this context, it is also pertinent to mention that large numbers of multifunctionalized DHPMs have found vibrant therapeutic use for the synthesis of antiviral, antitumor, antibacterial, and antiinflammatory drugs. , As a consequence, many catalytic methodologies, metal Lewis acids, Brønsted acids or bases, heterogeneous catalysts, and nonconventional techniques, such as microwave, ultrasound, high-pressure, and grindstone chemistry, have been developed to improve the synthesis of this attractive family of compounds. − However, most of these synthetic methodologies suffer from serious drawbacks like long reaction time, low yield, high reaction temperature, metal leaching, and solubility of the catalyst in the reaction medium. − Recently, there has been increasing awareness of the right legislation on the maintenance of “greenness” in the catalyst design and catalytic processes, and thus greener reaction pathways and methodologies are highly desirable in the field of chemical and materials research. , In this context, metal-free organocatalysis is one of the green catalytic methodological approaches in the field of synthetic organic chemistry. However, this strategy faced a lot of practical problems: (1) generally the homogeneous organocatalysts are soluble in a reaction medium and hence are very difficult to separate; (2) various hazardous organic solvents are used as the reaction medium to obtain optimum yield in a given reaction; (3) the reaction time is large; (4) the turnover numbers are low. − To avoid these problems, the use of a heterogeneous organocatalyst is a smart choice, particularly those that are designed based on functionalized mesoporous silicas because of their high surface area, tunable nanoscale pores, ease of the grafting of organic scaffolds to balance between the hydrophilic and hydrophobic character of the porous architecture, exciting host–guest chemistry, and supramolecular interaction to different extents with the reactant molecules. …”