Asymmetric Brønsted Acid Catalysis: Enantioselective Nucleophilic Substitutions and 1,4‐Additions

Abstract

Executive decision: Depending on the catalyst (both N-triflylphosphoramides), the highly enantioselective Brønsted acid catalyzed addition of indoles to α,β-unsaturated carbonyl compounds provides either α-keto esters (up to 92 % ee, left side of the scheme), or a novel type of bisindole (right), which displays atropisomerism. The α-keto esters can also be converted into amino acids by a one-pot 1,4-addition-reductive amination reaction.