An inorganic–organic hybrid material based on a Keggin‐type polyoxometalate@Dysprosium as an effective and green catalyst in the synthesis of 2‐amino‐4H‐chromenes via multicomponent reactions

• Published in: Applied organometallic chemistry Vol. 34; no. 9
• Main Authors: Hosseinzadeh‐Baghan, Sara, Mirzaei, Masoud, Eshtiagh‐Hosseini, Hossein, Zadsirjan, Vahideh, Heravi, Majid M., Mague, Joel T.
• Format: Journal Article
• Language: English
• Published: Chichester Wiley Subscription Services, Inc 01-09-2020
• Subjects: 2‐amino‐4H‐chromenes; Catalysts; Catalytic activity; Chemical synthesis; Chemistry; Clusters; Crystal structure; Dicarboxylic acids; Diffraction patterns; Dysprosium; Heteropoly acids; Infrared analysis; inorganic–organic hybrid; Keggin; Malononitrile; Naphthol; polyoxometalates; Polyoxometallates; Pyrazole; Room temperature; Structural analysis; Surface area; Thermogravimetric analysis; X-ray diffraction
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.5793

A novel inorganic–organic hybrid, [Dy4(PDA)4(H2O)11(SiMo12O40)]·7H2O denoted as (POM@Dy‐PDA), based on a lanthanide cluster, a Keggin‐type polyoxomolybdate, and PDA (1,10‐phenanthroline‐2,9‐dicarboxylic acid) was prepared and fully characterized by elemental analysis, Fourier‐transform infrared and UV–Vis spectroscopies, thermogravimetric analysis, powder X‐ray diffraction (PXRD), and single‐crystal X‐ray diffraction. The structural analysis study showed that the [SiMo12O40]4− ions reside in the interspace between two cationic layers as discrete counterions and are not coordinated to the rare‐earth ions. Significantly, this hybrid catalyst is a rare case of an inorganic–organic hybrid polyoxometalate (POM) with a PDA ligand based on CSD search (CSD version 5.40/November2018). The hybrid catalyst was further characterized via powder X‐ray diffraction (PXRD) pattern at room temperature which indicated the good phase purity of the catalyst. BET and Langmuir surface area analysis indicate surface area of POM@Dy‐PDA 6.6 and 51.3 m2g‐1, respectively. The catalytic activity of the hybrid catalyst was successfully examined in the synthesis of 2‐amino‐4H‐chromene derivatives through a multicomponent reaction. A three‐component, one‐pot reaction involving differently substituted benzaldehydes, resorcinol/α‐naphthol/β‐naphthol/4‐hydroxycoumarin/3‐methyl‐4H‐pyrazole‐5(4H)‐one, and malononitrile or ethyl cyanoacetate in the presence of a catalytic quantity of the aforementioned hybrid catalyst in EtOH/H2O under reflux condition gave the corresponding highly functionalized 2‐amino‐4H‐chromenes in satisfactory yields. The catalyst can be reused several times without appreciable loss in its catalytic activity.
A inorganic‐organic hybrid based on a lanthanide cluster, a Keggin‐type polyoxomolybdatewas prepared and fully characterized. X‐ray study showed that the Keggin ions reside in the interspace between two cationic layers as discrete counter‐ions. BET and Langmuir surface area analysis indicate surface areas of POM@Dy‐PDA 6.6 m2 g−1 and 51.3 m2 g−1, respectively. The catalytic activity of catalyst was successfully examined in the synthesis of 2‐amino‐4H‐chromene derivatives through a multicomponent reaction.
Highlights
A mild, simple, convenient, and efficient synthetic strategy was developed for the synthesis of biologically and pharmacologically active products.
A novel inorganic–organic hybrid, 2[Dy4(PDA)4(H2O)11(SiMo12O40)]·7H2O denoted as POM@Dy‐PDA), based on a lanthanide cluster, a Keggin‐type polyoxomolybdate, and PDA (1,10‐phenanthroline‐2,9‐dicarboxylic acid) was synthesized.
POM@Dy‐PDA catalyzed synthesis of 2‐amino‐4H‐chromenes via one‐pot multicomponent reactions.
This protocol is being performed under green conditions, isolating the desired products through facile work‐up procedure, in excellent yields.