Highly Efficient Silylcyanation of Ketones by a Catalytic Double Activation Method Using Lewis Acid and N-Oxide Catalysts

Fuxue Chen; Xiaoming Feng; Bo Qin; Guolin Zhang; Yaozhong Jiang

doi:10.1055/s-2003-37534

LETTER

Highly Efficient Silylcyanation of Ketones by a Catalytic Double Activation Method Using Lewis Acid and N-Oxide Catalysts

Fuxue Chen^b, Xiaoming Feng*^a, Bo Qin^a, Guolin Zhang^c, Yaozhong Jiang^b
^a Sichuan Key Laboratory of Green Chemistry and Technology, College of Chemistry, Sichuan University, Chengdu 610064, China
Fax: +86(28)85418249; e-Mail: xmfeng@pridns.scu.edu.cn;
^b Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China
^c Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China

Abstract

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Abstract

An efficient protocol for addition of TMSCN to ketones by employing 3 mol% achiral Schiff base-Ti(IV) complex as the Lewis acid and 3 mol% N-oxide as the Lewis base in a manner of double activation was described. Aromatic, aliphatic, cyclic and heterocyclic ketones all gave the racemic O-TMS cyanohydrins in good to excellent yields (up to 99%) under mild conditions.

Key words

cyanohydrins - double activation catalysis - ketones - N-oxides - Schiff bases

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Referenzen

References

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When the reaction was catalyzed by (1R,2R)-N,N′-bis(3,5-di-tert-butyl-salicylidene)-1,2-diphenyl-1,2-diamine-Ti(O-i-Pr)₄ complex (20 mol%) and achiral N-oxide 2 (20 mol%), the product was obtained in 95% yield with 67% ee at 0 °C for 84 h {GC [Varian, Chirasil DEX CB, column temperature = 100 °C (isothermal), injector temperature = 200 °C, detector temperature = 250 °C]: t _r(major) = 24.5 min, t _r(minor) = 25.4 min}.