Highly Enantioselective Addition of Dialkylzinc to Trifluoroacetophenones, Catalyzed by 1,2-Diamines. Synthesis of Key Fragments of Inhibitors of the Enzyme 11β-HSD1 and Kinetic Analysis of the Process

Nucleophilic Addition of Benzylboronates to Activated Ketones

A method has been developed for the addition of benzylboronic acid pinacol ester to activated ketones including trifluoromethyl ketones in good yields. The use of DABCO as an additive was found to enhance the rate and efficiency of this reaction. In reactions of ketones with a second carbonyl group present such as an ester or amide, good chemoselectivity for the ketone was observed. Competition experiments suggest an electrophile relative reactivity order of CF2H ketone > CF3 ketone > aldehyde under these reaction conditions.

Highly enantioselective addition of dimethylzinc to fluorinated alkyl ketones, and the mechanism behind it

Switching the solvent from toluene to dichloromethane results in a very important enhancement in the yield and enantiomeric excess of nucleophilic addition.

Chemo- and Enantioselective Addition and β-Hydrogen Transfer Reduction of Carbonyl Compounds with Diethylzinc Reagent in One Pot Catalyzed by a Single Chiral Organometallic Catalyst

Using a single chiral phosphoramide-Zn(II) complex as the catalyst, the asymmetric β-H transfer reduction of aromatic α-trifluoromethyl ketones and enantioselective addition of aromatic aldehydes with Et2Zn in one pot were successfully realized, affording the corresponding additive products of secondary alcohols in high yields (up to 99%) with excellent enantioselectivities (up to 98% ee) and the reduction products of α-trifluoromethyl alcohols in good to excellent yields with up to 77% ee.