Effective cyanosilylation of aldehydes with copper(II)-based polymeric catalysts

The new 1D copper(II) coordination polymers (CPs) [Cu(μ-L1)(H2O)]n (1, H2L1 = 2-(2-(4,4-dimethyl-2,6-dioxocyclohexylidene)hydrazinyl)benzoic acid) and [Cu(μ-H2L2)(H2O)]n (2, H4L2 = (Z)-2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)terephthalic acid) and the known zwitterionic 1D CP [Cu2(H2O)2(μ-H2L3)(μ-L3)]n (3, H3L3 = 2-(2-(4,4-dimethyl-2,6-dioxocyclo-hexylidene)hydrazinyl)terephthalic acid) were synthesized and tested as homogeneous catalysts for cyanosilylation of a variety of aldehydes to the corresponding cyanohydrin trimethylsilyl ethers. Among these polymeric catalysts, 3, with a zwitterionic charater, is the most effective one, giving 86–99% yield of the ethers upon reaction of aliphatic and aromatic aldehydes with trimethylsilyl cyanide in methanol at room temperature in 4 h. Non-covalent interactions (cation-π and tetrel bondings) involving the aldehyde substrate are proposed to assist the cyanosilylation reaction. © 2016 Elsevier B.V.