The Knoevenagel condensation reaction is a prominent organic reaction commonly being utilized in the total synthesis of natural and biologically potent products as a vital and frequently beginning step. Naturally occurring compounds having complex structures were demonstrated to exhibit significant biological properties. Due to numerous biological potencies, the total syntheses of them has fascinated and attracted much attention of synthetic organic chemists. In this review, we try to highlight the applications of the Knoevenagel reaction as the key step in the total synthesis of biologically active natural products.
Superparamagnetic Fe3O4is shown to act as a very efficient catalyst for the one-pot, three-component synthesis of 5,5-disubstituted hexahydropyrimidines and their spiropiperidines. The catalyst is easily recovered by the use of an external magnet and reused in several reactions without any noticeable loss of activity. The products are obtained in short time and good purity upon separation of the catalyst and evaporation of the volatiles of the reaction mixture.
A series of 1-(a-aminoalkyl) naphthols were synthesized expeditiously in good yields and selectivity from 2-naphthol, alkylamines and aldehydes in the presence of nanoparticle fe3o4 at room temperature in solvent-free conditions.
In this letter we report the synthesis of cellulose and vitamin C coated magnetite nanoparticles (MNPs) as a green catalyst for the synthesis of pharmacologically active 1-(α-aminoalkyl) Naphthols via a one-pot condensation of 2-naphthol, alkylamines and aldehydes under solvent-free conditions. The XRD results confirmed the pure magnetite phase for the prepared MNPs. Morphological observations of the prepared MNPs through SEM and TEM exhibited the uniform particle morphology with 15 nm in size. IR analysis presented all vibrations related to chemical bounds in the cellulose and vitamin C. TG analysis exhibits 12% vitamin C and 18% cellulose in MNPs composition. Magnetic analysis via VSM proved the superparamagnetic nature of the prepared MNPs.
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