Highly active bifunctional salenTi(IV) catalysts for asymmetric cyanosilylation of aldehydes and TMSCN |
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Authors: | Ye Qian Wen Wei Min Ren Xiao Bing Lu |
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Institution: | State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China |
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Abstract: | A novel enantiopure salen ligand bearing a diphenylphosphine oxide on the 3-position of one aromatic ring was synthesized and combined with Ti(Oi-Pr)4 as a monometallic bifunctional catalyst for asymmetric cyanosilylation reaction of aldehydes with trimethylsilyl cyanide (TMSCN). The catalyst system exhibited excellent activity and moderate enantioselectivity. The addition of TMSCN to 4-nitrobenzaldehyde in the presence of 1 mol% catalyst loading could complete within 10 min at ambient temperature. An intramolecularly cooperative catalysis was observed in this system wherein the central metal Ti(IV) is suggested to play a role of Lewis acid to activate aldehydes while the appended diphenylphosphine oxide worked as Lewis base to activate TMSCN. |
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Keywords: | Cyanohydrin Bifunctional catalyst Salen TMSCN Diphenylphosphine oxide |
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