Highly Enantioselective Friedel-Crafts Reaction of 4,7-Dihydro- indoles with β,γ-Unsaturated α-Keto Esters by Chiral Bronsted Acids

摘要

A highly efficient Friedel-Crafts reaction of 4,7-dihydroindoles with β,γ-unsaturated α-keto esters by a chiral N-triflyl phosphoramide was realized, affording the 2-substituted 4,7-dihydroindoles with up to 98% ee for a wide range of substrates. The Friedel-Crafts alkylation together with a subsequent oxidation of the product with p-benzoqui-none led to a 2-alkylated indole derivative in 98% ee.