作者:Alesandere Ortega、Rubén Manzano、Uxue Uria、Luisa Carrillo、Efraim Reyes、Tomas Tejero、Pedro Merino、Jose L. Vicario
DOI:10.1002/anie.201804614
日期:2018.7.2
Racemic cyclopropyl ketones undergo enantioselectiverearrangement to deliver the corresponding dihydrofurans in the presence of a chiral phosphoric acid as the catalyst. The reaction involves activation of the donor‐acceptor cyclopropane substrate by the chiral Brønsted acid catalyst to promote the ring‐opening event, thus generating a carbocationic intermediate that subsequently undergoes cyclization
One-pot Preparation of 2,6-Disubstituted 4-(Trifluoromethyl)pyrimidines <i>via</i> the Tandem Cyclization, Dehydration, and Oxidation Reaction of α,β-Unsaturated Trifluoromethyl Ketones Using POCl<sub>3</sub>-Pyridine-Silica Gel and MnO<sub>2</sub> Systems
The treatment of α,β-unsaturated trifluoromethyl ketones with amidines in acetonitrile gave the corresponding 4-hydroxy-4-(trifluoromethyl)-3,5,6-trihydropyrimidines, followed by successive dehydration with phosphorus oxychloride-pyridine-silica gel and oxidation with manganese(IV) oxide, producing 2,6-disubstituted 4-(trifluoromethyl)pyrimidines in good to excellent yields.
Strong influence of the trifluoromethyl group on the chemoselectivity of [3+2]-cycloadditions of thiocarbonyl S -methanides with α,β-unsaturated ketones
situ-generated reactive thiocarbonyl S-methanides were reacted with fluorinated enones. The type of the obtained [3+2]-cycloadduct depends strongly on the location of the activating CF3 group. In the case of enones containing the CF3CHCH moiety, the [3+2]-cycloaddition occurs chemo- and regioselectively onto the CC bond to give trifluoromethylated tetrahydrothiophene derivatives. On the other hand, enones containing
A novel N,N-dibenzyl diaminomethylenemalononitrile organocatalyst efficiently promotes asymmetric Henry reactions of trifluoromethyl enones with nitromethane, affording the corresponding highly functionalized products in high yields with excellent enantioselectivities (up to 90% ee).
A squaramide organocatalyst efficiently promoted the asymmetric Friedel–Crafts alkylation of α,β-unsaturated trifluoromethyl ketones with aromatic alcohols in a one-pot procedure, affording corresponding 6-trifluoromethyl-substituted 7,8-dihydrochromen-6-ol derivatives (up to 94% yield, 74% ee).