Ultrasound-Promoted Expedient and Green Synthesis of Diversely Functionalized 6-Amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)(aryl)methyl)pyrimidine-2,4(1H,3H)-diones via One-Pot Multicomponent Reaction under Sulfamic Acid Catalysis at Ambient Conditions

Abstract

Development of an ultrasound-promoted green protocol to access pharmaceutically relevant functionalized coumarin-uracil molecular hybrids, 6-amino-5-((4-hydroxy-2-oxo-2H-chromen-3-yl)(aryl)methyl)pyrimidine-2,4(1H,3H)-diones (4/ 4′), has been accomplished based on a three-component tandem reaction between 4-hydroxycoumarin (1), substituted aromatic aldehydes (2), and 6-aminouracils (3)/6-amino-2-thiouracil (3′) under sulfamic acid-catalysis in aqueous ethanol. Metal-free onepot synthesis, rapid reaction-rate with good to excellent yields, use of cost-effective and eco-friendly catalyst and solvent, energy efficiency, easy isolation of products without the need of column chromatographic purification, reusability of reaction media, largescale synthetic applicability, and excellent green credential parameters of the process are the salient features of this newly developed method.

Hybrid Cobalt Doped-Cerium Oxide as a Multifunctional Nanocatalyst for Various Organic Transformations

“…Sustainability is based on economic, societal, and environmental aspects along with the principle of green chemistry. , The highly atom economic synthesis of product depends on green, eco-friendly, benign process, prevention of waste generation, and waste elimination; these are the major driving force behind the development of green chemistry. , Co@CeO 2 NC-catalyzed reaction mostly produces nontoxic water as a byproduct. In this regard, the atom economy for all four model substrates was calculated and found to be in the range of 65–91% (Table S2).…”

4‐Hydroxycoumarin: A Versatile Substrate for Transition‐metal‐free Multicomponent Synthesis of Bioactive Heterocycles

“…Taking advantage of the high catalytic activity of sulfamic acid, Brahmachari et al ., synthesized a series of pharmaceutically relevant pyrimidine‐coumarin hybrid under ultrasound irradiation (Scheme 36). [93] The reaction was carried out by using readily available 4‐hydroxycoumarin 1 , aldehydes 37 , and 6‐aminouracils 93 or 6‐amino‐2‐thiouracil 95 as the starting material. This reaction required 30 mol% of sulfamic acid as the catalyst and aqueous ethanol as the solvent.…”

Dehydrative Substitution Reaction in Water for the Preparation of Unsymmetrically Substituted Triarylmethanes: Synthesis, Aggregation‐Enhanced Emission, and Mechanofluorochromism

“…Sulfamic acid has evolved as a commercially available, cheap watersoluble Brønsted acid catalyst. [54][55][56][57][58][59][60] Due to its zwitterionic nature, sulfamic acid is insoluble in common non-polar organic solvents but soluble in water. Therefore, sulfamic acid has been extensively used as a homogeneous catalyst in an aqueous medium.…”

“…The ease of handling solid acid catalysts and avoiding the use of volatile organic solvents will impart greenness in the process. Sulfamic acid has evolved as a commercially available, cheap water‐soluble Brønsted acid catalyst [54–60] . Due to its zwitterionic nature, sulfamic acid is insoluble in common non‐polar organic solvents but soluble in water.…”