Aqueous‐Mediated green synthesis of novel spiro[indole‐quinazoline] derivatives using kit‐6 mesoporous silica coated Fe₃O₄ nanoparticles as catalyst

Abstract

In this work, a series of eight new spiro[3,4′]1,3‐dihydro‐2H‐indol‐2‐one‐2′‐amino‐4′,6′,7′,8′‐tetrahydro‐2′,5’(1’H,3’H)‐quinazoline‐diones were successfully synthesized through a three‐component reaction of 1H‐indole‐2,3‐diones (isatins), guanidine nitrate, and 1,3‐cyclohexanediones, by use of Kit‐6 mesoporous silica coated Fe3O4 nanoparticles (Fe3O4@SiO2@KIT‐6) as a highly efficient magnetically separable nanocatalyst in aqueous media at 60°C. Several notable features of thiseco‐friendly protocol are high yields of products, short reaction times, operational simplicity, and the use of easily available and recyclable catalyst.

Ultrasound promoted and Kit‐6 mesoporous silica‐supported Fe3O4 magnetic nanoparticles catalyzed cyclocondensation reaction of 4‐hydroxycoumarin, 3,4‐methylenedioxyphenol, and aromatic aldehydes

“…The XRD image of the fresh and third recycled catalyst reuse, as expected T A B L E 1 Optimization of the reaction conditions for the synthesis of 7-phenyl-6H,7H- [1]benzopyrano [4,3-b] [1,3] showed no change in the catalyst structure after catalysis ( Figure 2). Based on the pervious literature, [51][52][53] and according the acidic sites of the Fe 3 O 4 @SiO 2 @Kit-6 nanocomposite, which was proved in our recent paper, [27] a suggested mechanism for the present reaction can be achieved via the following tandem reactions: formation alkene 6 by Knoevenagel condensation between 3,4-methylenedioxyphenol 2 and aromatic aldehyde 3, Michael addition of 4-hydroxycoumarin 1 to alkene 6, followed by cyclization and dehydration. Herein, the nanocomposite as the catalyst that has both acidic and basic sites on its surface facilitates the reaction by abstracting the acidic protons and also active carbonyl group for nucleophilic attack (Scheme 3).…”

“…Although the target compounds were synthesized for the first time in this research, such studies have been carried out in the synthesis of other heterocyclic compounds using Fe 3 O 4 @SiO 2 @Kit-6 as catalyst in different conditions. Comparison of the catalytic behavior of the Fe 3 O 4 @SiO 2 @Kit-6 in the present work with those [23][24][25][26][27] in terms of conditions, structures of products, yields, and operational simplicity is shown in Table 3.…”

“…Abdolmohammadi et al [27] 4-Hydroxycoumarin (1 mmol) In summary, the use of Fe 3 O 4 @SiO 2 @Kit-6 as a magnetically separable and reusable catalyst for the formation of 7-aryl-6H,7H- [1]benzopyrano [4,3-b…”

“…Among different supported MNPs, Kit-6 mesoporous silica-supported Fe 3 O 4 MNPs (Fe 3 O 4 @SiO 2 @Kit-6) has also been emerged as a powerful catalyst because it has preferable properties such as small dimensions, uniform porosity, high chemical stability, and easy magnetic separability. [23][24][25][26][27][28] The multicomponent reactions (MCRs) are now widely recognized as important synthetic tools towards complex and valuable scaffolds. [29,30] In recent years, the performance of organic syntheses using heterogeneous catalysts under ultrasonication as a versatile energy source is one of the main factors in green chemistry research.…”

Fe3O4@C@prNHSO3H: A novel magnetically recoverable heterogeneous catalyst in green synthesis of diverse triazoles

“…[ 32 ] Accordingly, the development of a stable and magnetically retrievable core/shell structured iron oxide nano‐catalyst with reusability and recyclability potentials is still challenging, and further, it adds significant value to synthetic organic protocols such as the multicomponent reactions (MCRs). [ 33–36 ]…”