Microwave Promoted, Sodium Acetate Catalyzed One Pot Synthesis of Poly Functionalized 4H‐Pyrans

Abstract

A clean and efficient one pot synthesis of 4H-pyran derivatives through condensation of aromatic aldehydes, malononitrile and dicarbonyl compounds under microwave irradiation in presence of Sodium acetate as a catalyst is described.

Chitosan-EDTA-Cellulose network as a green, recyclable and multifunctional biopolymeric organocatalyst for the one-pot synthesis of 2-amino-4H-pyran derivatives

“…(°C) (Lit.) Ref 1 4-ClC 6 H 4 5a 10 96 170–171 171–172 72 2 2-ClC 6 H 4 5b 20 94 180–181 179–181 72 3 4-NO 2 C 6 H 4 5c 15 92 173–175 175–176 72 4 3-NO 2 C 6 H 4 5d 15 91 180–182 182–184 73 5 2-FC 6 H 4 5e 20 85 159–161 158–160 74 6 4-BrC 6 H 4 5f. 25 93 171–173 172–173 75 7 3-Pyridine 5j 25 90 178–179 178–180 …”

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

“…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.…”

Fe3O4@RB@LDH: Efficient and Recyclable Photocatalyst Visible‐Light Mediated Synthesis of Pyran and Pyrrolidinone Derivatives and Their Anti‐Microbial Activities

“…Therefore, good efforts have been made by chemists for the synthesis of these heterocyclic scaffolds using numerous methodologies. A number of methods have been reported for the synthesis of pyran detivatives involving the multicomponent condensation of aldehydes, malononitrile and 1,3 cyclic diketones or substituted pyrazoles in presence of various catalysts such as (NH 4 ) 2 HPO 4 , [22] Na 2 SeO 4 , [23] CeCl 2 .7H 2 O, [24] SiO 2 @Pr@SO 3 H, [25] Cl 3 COOOH, [26] sodium acetate, [27] PFPA, [28] Fe 2 O 3 @SiO 2 @VB 1 NPs, [29] molecular iodine, [30] LiBr, [31] pyridinium p-toluenesulfonate, [32] NaF, [33] etc. In spite of the advantages of these synthetic methods, quite a few of them have some limitations such as harmful conditions, expensive catalyst, low yields, long reaction times, high temperature, difficult workup procedure etc.…”