Polymer Supported Nitrogen-Bridged Symmetrical Binuclear Dioxidomolybdenum(VI) Complexes and Their Homogeneous Analogues as Potential Catalysts for Efficient Synthesis of 2-Amino-3-Cyano-4H-Chromenes/Pyrans.

Autor: Maurya MR; Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India., Nandi M; Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India., Kumar N; Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247667, India., Avecilla F; Universidade da Coruña, Grupo NanoToxGen, Centro Interdisciplinar de Química y Biología (CICA), Departamento de Química, Facultade de Ciencias, Campus de A Coruna, 15071, A Coruna, , Spain.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2024 May 23; Vol. 30 (29), pp. e202400631. Date of Electronic Publication: 2024 Apr 15.
DOI: 10.1002/chem.202400631
Abstrakt: Reaction of 2-chloromethyl-1H-benzimidazole with known intermediates (i-iii), prepared from diaminoguanidine hydrochloride with salicylaldehyde, 5-bromosalicylaldehyde or 3,5-di-tert-butylsalicylaldehyde, in the presence of triethylamine (NEt 3 ) led to the formation of benzimidazole appended new ligands, H 4 L 1 -H 4 L 3 (I-III). The homogeneous nitrogen-bridged symmetrical binuclear complexes, [(Mo VI O 2 ) 2 (L 1 )(H 2 O) 2 ] (1), [(Mo VI O 2 ) 2 (L 2 )(H 2 O) 2 ] (2) and [(Mo VI O 2 ) 2 (L 3 )(MeOH) 2 ] (3) have been isolated by reacting these ligands with [Mo VI O 2 (acac) 2 ] in a 1 : 2 molar ratio in refluxing methanol. Using 1 : 1 (ligand to Mo precursor) molar ratio under above reaction conditions resulted in the corresponding mononuclear complexes, [Mo VI O 2 (H 2 L 1 )(MeOH)] (4), [Mo VI O 2 (H 2 L 2 )(H 2 O)] (5) and [Mo VI O 2 (H 2 L 3 )(MeOH)] (6). The binuclear heterogeneous compounds [(Mo VI O 2 ) 2 (L 1 )(DMF) 2 ]@PS (PS-1), [(Mo VI O 2 ) 2 (L 2 )(DMF) 2 ]@PS (PS-2) and [(Mo VI O 2 ) 2 (L 3 )(DMF) 2 ]@PS (PS-3) have been obtained by immobilization of 1-3 onto chloromethylated polystyrene (PS) beads. All synthesized ligands, homogeneous as well as supported compounds have been characterized by elemental analyses and various spectroscopic methods. Single crystal X-ray diffraction study of complexes 1 and 3 confirms their nitrogen-bridged symmetrical binuclear structures while 4 is mononuclear. Heterogeneous compounds (PS-1-PS-3) have further been studied by microwave plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy along with energy dispersive spectroscopy. These compounds (homogeneous and heterogeneous) were explored for catalytic applications to one-pot multicomponent reactions (MCRs) for efficient synthesis of biologically active 2-amino-3-cyano-4H-chromenes/pyrans (21 examples). Optimising various reaction parameters helped in achieving as high as 97 % yields of products. Though, only half equivalent of the binuclear complexes (1-3) was required compared to mononuclear analogues (4-6) to achieve comparable yields, heterogeneous catalysts have an added advantage due to their stability and recyclability. Suitable reaction mechanism has also been proposed based on isolated intermediates.
(© 2024 Wiley-VCH GmbH.)
Databáze: MEDLINE
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