Cinchona alkaloid/TMAF combination: Enantioselective trifluoromethylation of aryl aldehydes
摘要:
The catalytic enantioselective trifluoromethylation reaction of aromatic aldehydes using the Ruppert-Prakash reagent (Me3SiCF3) has been disclosed, with an operationally simple procedure, based on the combination of sterically demanding cinchona alkaloid-derived phase-transfer catalyst 3b with tetramethylammonium fluoride (TMAF). Our methodology provides medicinally important alpha-trifluoromethyl alcohols with high chemical yields and moderate to good enantioselectivities (50-70% ee). (c) 2013 Elsevier B.V. All rights reserved.
Asymmetric trifluoromethylation of aromatic aldehydes by cooperative catalysis with (IPr)CuF and quinidine-derived quaternary ammonium salt
作者:Shaoxiang Wu、Wei Zeng、Qi Wang、Fu-Xue Chen
DOI:10.1039/c2ob26827b
日期:——
A general enantioselective trifluoromethylation of aldehydes has been developed using (IPr)CuF and quinidine-derived quaternary ammonium salt as the cooperative catalyst. Thus, a wide range of aromatic aldehydes have been converted to the corresponding products in up to 92% yield and 81% ee at 2 mol% of catalyst loading. The greatly enhanced activity and enantioselectivity result from the initiative generation of active [(IPr)CuCF3] as well as additional coordination activation of other copper species.