One-pot synthesis of pyrrolo[1,2-a]indoles by chiral N-triflyl phosphoramide catalyzed Friedel-Crafts alkylation of 4,7-dihydroindole with β,γ-unsaturated α-keto esters

Article abstract of DOI:10.1002/cjoc.201200759

Chiral N-triflyl phosphoramide was found an efficient catalyst for the enantioselective Friedel-Crafts alkylation reaction of 4,7-dihydroindole with β,γ-unsaturated α-keto esters. In the presence of 5 mol% of the optimized catalyst, various pyrrolo[1,2-a]indoles were obtained in excellent enantioselectivity, moderate yields and up to 3:1 diastereoselectivity based on the one-pot synthesis including the Friedel-Crafts alkylation reaction and the subsequent p-benzoquinone oxidation.