Highly Enantioselective Copper-Catalyzed Electrophilic Trifluoromethylation of β-Ketoesters
作者:Qing-Hai Deng、Hubert Wadepohl、Lutz H. Gade
DOI:10.1021/ja3039773
日期:2012.7.4
Enantioselective Cu-catalyzed trifluoromethylation of β-ketoesters using commercially available trifluoromethylating reagents is reported. A number of α-CF(3) β-ketoesters are obtained with up to 99% ee. The trifluoromethylated products were then transformed diastereoselectively to α-CF(3) β-hydroxyesters with two adjacent quaternary stereocenters via a Grignard reaction.
报道了使用市售三氟甲基化试剂对 β-酮酯进行对映选择性 Cu 催化的三氟甲基化。获得了许多具有高达 99% ee 的 α-CF(3) β-酮酯。然后通过格氏反应将三氟甲基化产物非对映选择性地转化为具有两个相邻季立体中心的 α-CF(3) β-羟基酯。
Enantioselective electrophilic trifluoromethylation of β-keto esters with Umemoto reagents induced by chiral nonracemic guanidines
Chiral nonracemic guanidines act as Brønsted bases to generate guanidinium enolates for the enantioselective electrophilic trifluoromethylation of β-keto esters by means of S-(trifluoromethyl)dibenzothiophenium tetrafluoroborate (Umemoto reagent) with good enantioselectivity of 60–70% range. Despite the fact that the ees are still improvable, the model reported in this work could spark the imagination