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).