photoepoxidation of α,β-unsaturated ketones driven by visible light in the presence of tetramethylguanidine (3b), tetraphenylporphine (H2TPP), and molecular oxygen under mild conditions was revealed. The corresponding α,β-epoxy ketones were obtained in yields of up to 94% in 96 h. The reaction time was shortened to 4.6 h by flow synthesis. The mechanism related to singlet oxygen was supported by experiments
A novel and efficient aldol reaction of readily available vinyl azides with trifluoromethyl ketones by copper catalysis is developed. The reaction is proposed to go through a nucleophilic trapping of vinyl azides with trifluoromethyl ketones as a trifluoromethyl source, leading to the assembly of diverse trifluoromethylated compounds under mild conditions in satisfactory yield.
Diastereoselective and Enantioselective Epoxidation of Acyclic β-Trifluoromethyl-β,β-Disubstituted Enones by Hydrogen Peroxide with a Pentafluorinated Quinidine-Derived Phase-Transfer Catalyst
efficient catalytic asymmetric epoxidation of β‐trifluoromethyl‐β,β‐disubstituted unsaturated ketones has been achieved by a pentafluorine‐substituted phase‐transfer catalyst with hydrogenperoxide (30%). Thus, the β‐trifluoromethyl‐α,β‐epoxy ketones with a quaternary carbon centre were obtained in excellent diastereoselectivities (up to 100:1 dr) and excellent enantioselectivities (up to 99.7% ee). Low catalyst
The distinctive fluorine effects on “on-water” chemistry have remained less explored. In this work, an “on-water” reaction of β-trifluoromethylated enones with phosphine oxides was developed for the preparation of highly functionalized gem-difluorodienes with excellent Z-selectivity. The reaction occurred through a well-designed tandem phospha-Brook rearrangement and defluorination sequence under
Cu-catalyzed asymmetric construction of a chiral quaternary center bearing CH3 and CF3 groups was achieved with high to excellent enantioselectivity using our originally developed ligands. The asymmetric conjugate addition of Me3Al to β-CF3-substituted enones and unsaturated ketoesters proceeded efficiently. The use of unsaturated ketoesters gives optically active furanones in high yields with high
使用我们最初开发的配体,铜催化的带有CH 3和CF 3基团的手性四元中心的不对称结构具有高至优异的对映选择性。 Me 3 Al 与β-CF 3取代的烯酮和不饱和酮酯的不对称共轭加成反应有效进行。使用不饱和酮酯以高产率和高对映选择性产生光学活性呋喃酮。全氟烷基取代的烯酮似乎不利于本反应。