Chiral Aldehyde–Palladium Catalysis Enables Asymmetric Synthesis of α-Alkyl Tryptophans via Cascade Heck-Alkylation Reaction
Qi-Wen Shen, Wei Wen, Qi‐Xiang Guo
Abstract
The first catalytic asymmetric cascade Heck-alkylation reaction of NH 2 -unprotected amino acid esters with N -(2-iodophenyl)allenamides is reported in this work. Under the promotion of a combining catalytic system comprising a chiral aldehyde, a chiral palladium complex, and the Lewis acid ZnCl 2, the title reaction takes place smoothly, giving optically active α-alkyl tryptophan derivatives in moderate to good yields and excellent enantioselectivities. The target products can be converted into other structurally complex chiral indoles without the loss of enantioselectivities.
Topics & Concepts
ChemistryAldehydePalladiumCatalysisAlkylationAlkylEnantioselective synthesisHeck reactionOrganic chemistryCascadeCombinatorial chemistryChromatographyCatalytic C–H Functionalization MethodsAsymmetric Synthesis and CatalysisAsymmetric Hydrogenation and Catalysis