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论文类型：期刊论文

发表时间：2011-09-21

发表刊物：ORGANIC & BIOMOLECULAR CHEMISTRY

收录刊物：SCIE、EI、PubMed、Scopus

卷号：9

期号：18

页面范围：6323-6330

ISSN号：1477-0520

摘要：A series of unsymmetric salen ligands derived from 1,2-diaminocyclohexane bearing an appended Lewis base on the three-position of one aromatic ring were synthesized by the reaction of various functional salicyaldehydes with the condensation product of 1,2-diaminocyclohexane mono(hydrogen chloride) and 3,5-di-tert-butylsalicylaldehyde. These ligands in conjunction with Ti(O(t)Pr)(4) exhibited excellent activity in catalyzing the cyanosilylation of aldehydes with trimethylsilyl cyanide (TMSCN) at mild conditions. The highest activity was observed in the catalyst system with regard to the salen ligand bearing a diethylamino group, which proved to be active even at a high [aldehyde]/[catalyst] ratio up to 50000. In a low catalyst loading of 0.05 mol%, the quantitative conversion of benzaldehyde to the corresponding cyanosilylation product was found within 10 min. at ambient temperature. An intramolecularly cooperative catalysis was proposed wherein the central metal Ti(IV) is suggested to play a role of Lewis acid to activate aldehydes while the appended Lewis base to activate TMSCN.