Insight into the catalytic properties and applications of metal–organic frameworks in the cyanosilylation of aldehydes

Abstract

Here we present a systematic investigation of the cyanosilylation of aldehydes with trimethylsilyl cyanide (TMSCN) by using metal-organic frameworks (MOFs) as the catalysts. Four types of thermal stable MOFs (MIL-47 (V), MIL-53 (Al), MIL-101 (Cr), and UiO-66 (Zr)) constructed with the same organic linker, terephthalic acid, were studied, among which MIL-101 (Cr) exhibits the highest catalytic activity. Experimental results revealed that the catalytic activities are in close relation with the types of coordinatively unsaturated metal ions, pore sizes as well as solvents. Using MIL-101 (Cr) as the catalyst, both aliphatic and aromatic aldehydes were efficiently transformed to cyanohydrin trimethylsilyl ether, meanwhile significant size selectivities and electronic effects have also been observed. The solvent-free reaction conditions not only provide a high TON for MOF catalyzed cyanosilylation, but also render current protocol more attractive to industrial applications.

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

“…The size selectivity of MOF ( 8 ), was also tested using 1‐naphthal and 9‐anthryl aldehydes as substrates. Significant size selectivity was observed with MIL‐101(Cr) and yields for both substrates decrease as compared with benzaldehyde in the following order: benzaldehyde>1‐naphthaldehyde>9‐anthraldehyde . The authors proposed a mechanism for the cyanosilylation reaction with MOF ( 8 ) which is provided below (Figure ).…”

“…Zhang and co‐workers studied the cyanosilylation reaction using various MOFs, for example, MIL‐47 (V) ( 6 ), MIL‐53 (Al) ( 7 ), MIL‐101 (Cr) ( 8 ), and UiO‐66 (Zr) ( 9 ) (Figure ) . All these MOFs are based on same terepthalic acid ligand, however, the metal ion present in them is different than the examples described above.…”

“…This synergistic behaviour improve both activity and scope of this catalyst and it gives better results in case of both electron withdrawing and donating groups while all previous MOFs did so in case of electron withdrawing groups only . Larger pore size in case MIL‐101(Cr) ( 8 ) in comparison to MIL‐47(V), MIL‐53(Al) and UiO‐66(Zr) facilitates the easy separation of product and increase the percentage yield . Similar results are obtained with hierarchical porous Cu based MOF, HP‐CuBTC ( 10 ) compared to above mentioned MOFs and pristine Cu‐BTC, as it shows higher activity due to embedded micro and meso pores in the same structure .…”

Cyanosilylation of Aldehydes Catalyzed by Ag(I)- and Cu(II)-Arylhydrazone Coordination Polymers in Conventional and in Ionic Liquid Media

“…The main synthetic route for the synthesis of cyanohydrins is the catalytic addition of the cyano group to a carbonyl compounds. Trimethylsilyl cyanide (TMSCN) is a frequently explored substrate for catalytic cyanation reaction since it is easy to handle, it has a high atom economy without providing side reactions, and its Si-C bond has low dissociation energy (Scheme 1) [2][3][4][5][6][7], therefore, contrasting with the toxic nature of other cyanide sources such as HCN, NaCN, KCN, etc. Numerous catalysts, including Lewis acids [8][9][10], Lewis bases [11][12][13], oxazaborolidinium ion [14,15], amino-thiourea [16,17], organic-inorganic salts [18][19][20][21][22], N-heterocyclic carbenes [23,24], nonionic bases [25,26], Ti,Al-phosphine oxide bifunctional species with carbohydrate or binaphthol scaffolds [27][28][29], Ti,Al-N-oxide bifunctional catalysts with proline, pyrrolidine and 1,2-diamino ligands [30][31][32], V-, Mn-, Al-, and Ti-salen complexes [33][34][35][36], chiral Ti-α,α,α,α-1,3-dioxolane-tetraaryl-4,5-dimethanols [37,38], Cu(II) and Co(II/III) hydrazone complexes [39,40] and also metal organic frameworks (MOFs) [41]…”

CoFe2O4/TMU‐17‐NH2 as a hybrid magnetic nanocomposite catalyst for multicomponent synthesis of dihydropyrimidines

“…Over the past three decades, the synthesis of metal–organic frameworks (MOFs) as porous crystalline hybrid materials by assembling metal nodes and organic ligands has attracted considerable attention with the aim of finding meaningful applications in various fields such as gas storage and separation, drug delivery, optics, sensing and biomedical imaging . Due to the diversity in metal centres and functional groups, high surface area and tunable porosity, MOFs can be valid as versatile heterogeneous catalysts . Among various catalyst separation techniques in organic synthesis, a simple magnetic isolation process eliminates the requirement of catalyst filtration and centrifugation; so, MOFs based on a magnetic support provide easy manipulation.…”