A perfect double role of CF3 groups in activating substrates and stabilizing adducts: the chiral Brønsted acid-catalyzed direct arylation of trifluoromethyl ketones
Asymmetric Arylation of 2,2,2-Trifluoroacetophenones Catalyzed by Chiral Electrostatically-Enhanced Phosphoric Acids
作者:Jie Ma、Steven R. Kass
DOI:10.1021/acs.orglett.8b00900
日期:2018.5.4
A series of highly reactive metal-free chiralphosphoricacids possessing positively charged phosphonium ion substituents are reported and have been applied to Friedel–Crafts alkylations of indoles and 2,2,2-trifluoromethyl aryl ketones. These catalysts are orders-of-magnitude more active and have similar or better enantioselectivities than their noncharged analogues. High tolerance to a range of substrates
The effect of pressure (up to 10 kbar) on the Brønsted acid catalyzedenantioselective hydroxyalkylation of indoles with trifluoromethyl ketones was explored. The reaction was effectively accelerated at 9 kbar with a very low loading of a 1,1′‐bi‐2‐naphthol (BINOL) ‐derived phosphoric acid (0.05–0.2 mol % of TRIP) and provided the products with high enantioselectivity (84–98 % ee).