Green synthesis of 3,4‐disubstituted isoxazol‐5(4H)‐ones using ZnO@Fe₃O₄ core–shell nanocatalyst in water

Abstract

An effective and environmentally benign methodology for the synthesis of isoxazol‐5(4H)‐one derivatives has been developed using a ZnO@Fe3O4 core–shell nanocatalytic system. The one‐pot, multicomponent reaction of an aromatic/heterocyclic aldehyde, hydroxylamine hydrochloride and ethyl acetoacetate under aqueous conditions at slightly elevated temperature resulted in the formation of title compounds in extremely good yields. The present new protocol is environmentally friendly as it offers heterocyclization with some interesting promising features such as safety, atom efficiency, low cost, mild conditions, minimal waste, catalyst recyclability, water as a solvent, easy workup and possession of excellent functional group tolerance for the synthesisis of structurally diverse isoxazole derivatives. All products were characterized by spectral and analytical methods. A representative title derivative was studied for its structure by single crystal X‐ray diffraction method.

Silica Supported Synthesis and Quorum Quenching Ability of Isoxazolones Against Both Gram Positive and Gram Negative Bacterial Pathogens

“…This protocol (Scheme 2) was further exploited to study its versatility, by subjecting various substituted aromatic aldehydes as well as heteroaromatic aldehyde to give corresponding Isoxazolones in very good yields (Table 2). Characterization studies of prepared compounds revealed parallel similarities with the reported literature data and undoubtedly supported the assigned structures [25–44] …”

“…Literature analysis [20–44,55–57] revealed this synthetic methodology to be one of the robust method for preparing Isoxazolone derivatives with more labile functional groups. Thus provide scope for development of functionally sensitive or even optically active Isoxazolones, keeping in mind their growing importance in medicinal field.…”

“…Characterization studies of prepared compounds revealed parallel similarities with the reported literature data and undoubtedly supported the assigned structures. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] A probable mechanism for this silica supported transformation is given in Scheme 3. The role of silica is herein depicted for activating the dicarbonyl reactant as well as aldehyde and further facilitating the dehydration.…”

Catalytic Approaches to Multicomponent Reactions: A Critical Review and Perspectives on the Roles of Catalysis

“…This example of multicomponent synthesis showed the importance of studies on solvent effects and how these effects are associated with the catalytic action in the MCR. Although there are three possible mechanisms debated for ISX formation [ 169 , 170 , 171 , 172 , 173 , 174 , 175 ], the synthetic enzyme efficiently selected only one of them, as shown in Scheme 11 . Water proved to be the best solvent, likely due to its hydrogen bond acidity (α) ability.…”

An efficient, multicomponent synthesis of aminoalkylnaphthols via Betti reaction using ZSM‐5 as a recoverable and reusable catalyst

“…[ 46 ] Therefore, considering the wide range biological applications of Betti bases and the unique properties of ZSM‐5 as an ideal catalyst. As a part of our program aiming at developing an efficient and environmentally friendly catalytic system for common organic transformations, [ 47–50 ] herein we to report an efficient, simple, and modified Mannich‐type synthesis of Betti bases or 1‐(α‐aminoalkyl)‐2‐naphthols from 2‐naphthol, aromatic aldehydes and different aliphatic amines (cyclic) using H‐ZSM‐5 zeolite as catalyst (10 mol%) at room temperature in quantitative yield ( Scheme 1 ) .…”