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Wang, W. T.; Lin, L. L.; Liu, X. H.; Feng, X. M., Science of Synthesis Knowledge Updates, (2011) 4, 436.
In 2011, Ohkuma and co-workers reported an efficient asymmetric conjugate addition of hydrogen cyanide to α,β-unsaturated ketones catalyzed by the combined system of complex 19 and lithium phenolate (Scheme 56).[94] In the presence of only 0.01–0.05 mol% of catalyst, a wide range of enones have been examined, giving the corresponding β-cyano ketones 118 in excellent yields and enantiomeric excesses. Notably, the ruthenium complex 19 can be recovered by column chromatography on silica gel from the reaction mixture in the open air, and is reusable at least five times without any loss of either catalytic activity or enantioselectivity. This protocol offers a highly efficient process for the practical synthesis of chiral β-cyano ketones.
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References
[94] | Meeeee, M.; Mee, M.; Meeeeeeee, M.; Meeeee, M.; Meeeee, M., Meeee. Meee., (8888) 888, 8888; Meeee. Meee. Mee. Me., (8888) 88, 8888. |