A highly enantioselective Friedel–Crafts alkylation of indoles with ethyltrifluoropyruvate has been developed using N,N′-dioxide-zinc(II) complexes. Both enantiomers of the desired adducts were obtained by the use of enantiomeric ligands in excellent results (up to 99% yield and 98% ee) within 0.5 h under mild conditions. On the basis of the experimental results, a proposed working model was proposed
Solkane® 365mfc is a proven environmentally benign alternative solvent for catalyst-free Friedel–Crafts (F–C) alkylations of indoles with trifluoropyruvate and glyoxylate. Their enantioselective variants are also achieved by virtue of the high-affinity of fluorous cinchona alkaloids catalysts to Solkane® 365mfc to provide F–C adducts in excellent yields with good to excellent ees (up to 96% ee).
Asymmetric Calcium Catalysis: Highly Enantioselective Carbonyl-Ene and Friedel-Crafts Reactions for the Synthesis of Quaternary α-Hydroxy Esters Bearing a Trifluoromethyl Group
Enantioselectivecalcium‐catalyzed addition reactions of styrene and indole derivatives with trifluoropyruvates have been developed. The alkaline‐earth metal‐catalyzed reactions proceed smoothly to afford the corresponding products in high yields and with good to excellent enantioselectivities under mild reaction conditions.
Chiral Brønsted-Acid-Catalyzed Enantioselective Arylation of Ethyl Trifluoroacetoacetate and Ethyl Trifluoropyruvate
作者:Jing Nie、Guang-Wu Zhang、Lian Wang、Dong-Hua Zheng、Yan Zheng、Jun-An Ma
DOI:10.1002/ejoc.200900353
日期:2009.7
Chiral phosphoric acid was found to be an effective organocatalysts for the direct enantioselectivearylation of ethyl 4,4,4-trifluoroacetoacetate (ETFAA). A series of chiral trifluoromethyl-substituted tertiary alcohols were obtained in moderate to high yields with up to 78 % ee. Several desired products were obtained with excellent optical purities after a single recrystallization. This method was
Asymmetric Friedel-Crafts Reaction of Indoles with Ethyl Trifluoropyruvate Using a Copper(I)-Bisoxazolidine Catalyst
作者:Christian Wolf、Peng Zhang
DOI:10.1002/adsc.201000918
日期:2011.3.28
Bisoxazolidine 1 is an effective ligand in the copper(I)‐catalyzed Friedel–Craftsreaction of alkyl trifluoropyruvates and indoles. A range of ethyl 2‐(3′‐indolyl)‐3,3,3‐trifluoro‐2‐hydroxypropanoates was produced in up to 99% yield and 94% ee within 30 min to 4 h. The effect of temperature on conversion and enantioselectivity proved to be substrate specific and was optimized individually. Of particular