A practical asymmetric conjugate addition to cycilic enones with chiral bifunctional Ru amido catalysts

作者：Dub Pavel A; Wang Hui; Watanabe Masahito; Gridnev Ilya D; Ikariya Takao^*

来源：Tetrahedron Letters, 2012, 53(27): 3452-3455.

DOI：10.1016/j.tetlet.2012.04.100

• Bifunctional catalyst
• Asymmetric Michael addition
• Cyclic enone
• C-C bond formation
• Ru catalyst

A practical asymmetric C-C bond formation to synthetically useful beta-chiral cyclic ketones (%26gt;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) %26gt; Ru(Pfbsdpen)(hmb) %26gt; Ru(Tsdpen)(hmb) %26gt; 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 enantio-selectivity has been experimentally demonstrated. Valuable information for the reaction mechanism was accumulated.

• 出版日期2012-7-4