A practical asymmetric conjugate addition to cyclic enones with chiral bifunctional Ru amido catalysts |
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| Authors: | Pavel A. DubHui Wang Masahito WatanabeIlya D. Gridnev Takao Ikariya |
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| Affiliation: | Department of Applied Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan |
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| Abstract: | A practical asymmetric C-C bond formation to synthetically useful β-chiral cyclic ketones (>99% ee) using bifunctional chiral amido Ru catalysts under an S/C = 1000, the highest ratio achieved so far in the literature for this class of reactions, is described. The catalytic reactivity decreases in the order of Ru(Msdpen)(hmb) > Ru(Pfbsdpen)(hmb) > Ru(Tsdpen)(hmb) > Ru(PMsdpen)(hmb), where Ru(Pfbsdpen)(hmb) is a newly developed chiral bifunctional catalyst. Complex Ru(Msdpen)(hmb) was identified as the best in terms of reactivity and enantioface selectivity, whereas Ru(PMsdpen)(hmb) gave unsatisfactory results. An importance of the NH proton in the bifunctional catalyst for determining the enantioselectivity has been experimentally demonstrated. Valuable information for the reaction mechanism was accumulated. |
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| Keywords: | Bifunctional catalyst Asymmetric Michael addition Cyclic enone C-C bond formation Ru catalyst |
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