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Enantioselective cyanosilylation of ketones by a catalytic double-activation method with an aluminium complex and an N-oxide
Abstract
Double-activation catalysis promises high catalytic efficiency in the enantioselective cyanosilylation of ketones through the combined use of a Lewis acid and a Lewis base. Catalyst systems composed of a chiral salen-A1 complex and an N-oxide have high catalytic turnovers (200 for aromatic ketones, 1000 for aliphatic ones). With these catalysts, a wide range of aliphatic and aromatic ketones were converted under mild conditions into tertiary cyanohydrin O-TMS ethers in excellent yields and with high enantioselectivities (94% ee for aromatic ketones, 90% ee for aliphatic ones). Preliminary mechanistic studies revealed that the salen-A1 complex played the role of a Lewis acid to activate the ketone and the N-oxide that of a Lewis base to activate TMSCN; that is, double activation- 期刊论文
- Asymmetric Catalysis
- Cyanohydrins
- Double Activation
- Enantioselectivity
- Ketones
- Chemistry, Multidisciplinary
- cyanohydrins
- enantiomers
- ketones
- hydroxycyanides
- hydroxynitriles
- antipodes, optical
- enantiomorphs
- isomers, mirror-image
- mirror-image isomers
- optical antipodes
- enantiomeric compounds
- enantioselectivity
- 酮
- diketones
- cetones
- ketone