Multicomponent synthesis of 4H-pyran derivatives using KOH loaded calcium oxide as catalyst in solvent free condition

Abstract

A Convenient and green synthesis of 4H-pyran derivatives via one-pot multicomponent reaction of aromatic aldehydes, malononitrile and ethyl acetoacetate using KOH loaded CaO as a catalyst under solvent free condition is reported. The morphology of the catalyst has been characterized by XRD and TEM. This protocol have numerous advantages like lesser reaction time, environment friendly, low cost, easy to separate, and provide higher yield. The synthesized compounds have been characterized and confirmed by different spectroscopic techniques like 1 H NMR, 13 C NMR, FT-IR, and LC-MS.

In water, Green and Efficient Multicomponent Synthesis of 4H-Pyran Derivatives catalyzed by LiOH·H 2 O under Ultrasound Irradiation

“…Additionally, yields ranged between 88% and 92% for reaction times varying from 10 to 120 minutes at 60°C using CaO/KOH as a catalyst under solvent-free conditions [49].…”

“…The synthesis of pyran derivatives has garnered widespread attention among researchers owing to their signi cance, prompting exploration through various methodologies, including microwave [33] and ultrasound irradiation in water [17,26,34] as well as the use of different catalysts under various conditions such as: halide ions [35][36], ionic liquids [37][38][39], triethylamine (NEt 3 ) [26], sophisticated organocatalysts potassium-N-oxyl phthalimide [40], heterogeneous catalysts [41], alkalin metallo-organic ([Mg 3 (NDC) 3 (DMF) 4 ]-H 2 O) [42], magnetic nanoparticles [43], polyethylene glycol (PEG) [44], piperidine [45], NaOH in water [46], 1,8-diazabicyclo [5. 4.0] undec-7-ene (DBU) in water [47], LiBr in water [48], sodium acetate combined with microwave irradiation [33], and CaO/KOH under solvent-free conditions [49]. However, while these methods exhibit varying degrees of success, they also present drawbacks such as elevated temperatures, moderate yields, limited applicability, prolonged reaction times, and reliance on harmful or costly solvents or catalysts.…”