Catalytic Enantioselective Alkynylation of Trifluoromethyl Ketones: Pronounced Metal Fluoride Effects and Implications of Zinc-to-Titanium Transmetallation
作者:Guang-Wu Zhang、Wei Meng、Hai Ma、Jing Nie、Wen-Qin Zhang、Jun-An Ma
DOI:10.1002/anie.201007341
日期:2011.4.4
(L1 and L2), was developed for the synthesis of both enantiomers of trifluoromethylated propargylic tertiary alcohols in high yield and enantioselectivity. Small amounts of BaF2 were found to be essential for maintaining high levels of reactivity and enantioselectivity.
new chiral CCN Rh catalysts containing N‐heterocyclic carbene and oxazoline hybrid ligands is described. The catalytic reaction of fluoroalkyl‐substituted ketones, ArCOCF2X (X=F, Cl, H), with aromatic and aliphatic alkynes yielded the corresponding chiral propargyl alcohols with high enantioselectivity. Control and kinetic experiments suggested a bis(alkynyl) Rh intermediate as the active species for
Enantioselective alkynylation of trifluoromethyl ketones catalyzed by chiral Schiff bases in the presence of Me2Zn afforded the corresponding trifluoroalkynyl alcohols in up to 66 % ee.