Metal‐Organic Frameworks as Platform for Lewis‐Acid‐Catalyzed Organic Transformations

Abstract

Metal-organicframeworks (MOFs)are highly promising Lewis acid catalysts;t hey either inherently possess Lewis acid sites (LASs) on it or the LASs can be generated through various post-synthetic methods, the later can be performed in MOFs in at rivial fashion. MOFs are suitable platform for catalysis because of its highly crystalline and porous nature.M oreover,w ith recent advancements, thermal and chemical stability is not ap roblem with many MOFs. In this Minireview, an enormousv ersatility of MOFs,i n terms of their microporosity/mesoporosity,s ize/shapes elec-tivity,c hirality,p ore size, etc.,h as been highlighted. These are advantageous for designing and performing various targeted organic transformations. Although, many organic transformations catalyzed by MOFs with LASs have been reported in the recent past. In this Minireview,w eh ave restricted ourselves to four important organic reactions:(i) cyanosilylation,( ii)Diels-Alder reaction, (iii)C ÀHa ctivation,a nd (iv) CO 2 -addition.T he discussion focuses mostly on the recentr eports (42 examples). Cyanosilylation ReactionCyanosilylation reaction which is nucleophillic addition of trimethylsilylcyanide (TMSCN) to carbonyl compounds producing cyanohydrins is av ery important organic transformation. Cyanohydrins are considered as versatile building blocks for fine chemicals, agrochemicals and pharmaceuticals, that is, a-hydroxyacids, b-hydroxyamines, a-aminonitriles, a-hydroxyketones and b-aminoalcohols. [41][42][43][44] In contrast to other toxic substancess uch as KCN, HCN and NaCN, TMSCN is ap referred reagent for cyanosilylation reactiona si ti se asy to handle, the SiÀCb ond has low dissociation energy andm ost importantly it [a] A.

Iron Complexes Anchored onto Magnetically Separable Graphene Oxide Sheets: An Excellent Catalyst for the Synthesis of Dihydroquinazoline-Based Compounds

“…On the basis of the above outcomes, we proposed a probable reaction pathway for the initial steps where the homogeneous catalyst (FeL) impact the syntheses of dihydroquinazoline compounds, as displayed in Scheme . In the first step, oxygen from the paraformaldehyde uses its lone e – pair to attack on the Fe­(III) center of complexes 1–3 with a simultaneous displacement of a loosely held DMF solvent to produce a Lewis acid–base adduct ( A ) through a dative bond. , Thus, the presence of catalyst complexes 1–3 triggers the formation of species A . Further attack on the carbonyl carbon is executed by the lone pair of the aniline nitrogen center.…”

“…In the first step, oxygen from the paraformaldehyde uses its lone e − pair to attack on the Fe(III) center of complexes 1−3 with a simultaneous displacement of a loosely held DMF solvent to produce a Lewis acid−base adduct (A) through a dative bond. 65,66 Thus, the presence of catalyst complexes 1−3 triggers the formation of species A. Further attack on the carbonyl carbon is executed by the lone pair of the aniline nitrogen center.…”

One‐Pot Conversion of Glucose into 5‐Hydroxymethylfurfural using MOFs and Brønsted‐Acid Tandem Catalysts

“…The isomerization reaction is catalyzed by Lewis acid‐type centers, and metal–organic frameworks (MOFs) can act as Lewis acids ,[ 17 ] . [ 20 ] Then, the second reaction (dehydration of fructose to HMF) requires Brønsted‐acid catalysts, [ 3 ] and in this case, a polyoxometalate (POM) was selected.…”

Complete and Versatile Post‐Synthetic Modification on Iron‐Triazole Spin Crossover Complexes: A Relevant Material Elaboration Method

“…Therefore the synthesis of a wide variety of molecules is facilitated and this is of particular interest in the fields of catalysis (where the catalytic activity is highly dependent on the structure of the catalyst) and sensors (where the selectivity towards guest molecules could be modulated by the electronic and steric hindrance of the functionalized group on the MOF). [2,17,19,[28][29][30][31][32][33] This strategy allows to have better control in the final material; two important examples of this are: 1) in the biological area; once the protein is biosynthesized, it can be covalently modified on the amino acid side chain or in the backbone of the protein, the phosphorylation being the most common post-translational modification (PTM). [34] 2) in coordination chemistry, to generate co-catalysts associating MOF with multimetal sites to avoid competition between the metal sites, [22,29,35] for example, Neppolian et al [35] synthesized Ti-MOF complexes and then associated them by the coordination of the amino functional group on the Ti-MOF to transition metals such as Ni or Cu.…”

“…An advantage of biphasic reaction is that the material can be simply isolated and recovered since it is not in the same phase than other reagents. Therefore the synthesis of a wide variety of molecules is facilitated and this is of particular interest in the fields of catalysis (where the catalytic activity is highly dependent on the structure of the catalyst) and sensors (where the selectivity towards guest molecules could be modulated by the electronic and steric hindrance of the functionalized group on the MOF) [2,17,19,28–33] . This strategy allows to have better control in the final material; two important examples of this are: 1) in the biological area; once the protein is biosynthesized, it can be covalently modified on the amino acid side chain or in the backbone of the protein, the phosphorylation being the most common post‐translational modification (PTM) [34] .…”