Highly Enantioselective Ring‐Opening Reactions of Aziridines with Indole and Its Application in the Building of C₃‐Halogenated Pyrroloindolines

Abstract

A magnesium-catalyzed asymmetric ring-opening reaction of aziridine with indole has been realized by employing commercially available chiral ligands. Both of the enantiomers of the ring-opening product could be obtained with good yields and a high level of enantioselectivity. The corresponding ring-opening product could be further transformed to various types of enantioenriched C3 -halogenated-pyrroloindolines.

Cu(I)-Catalyzed Enantioselective Friedel–Crafts Alkylation of Indoles with 2-Aryl-N-sulfonylaziridines as Alkylating Agents

“…9,10 The only example of catalytic asymmetric Friedel−Crafts-type ring opening of aziridines employing indoles as nucleophiles in a magnesium-catalyzed desymmetrization of meso-aziridines was reported very recently by Wang and co-workers. 11 Interestingly, when 3-substituted indoles were used as substrates, [3 + 2] cycloaddition reactions with aziridines occurred with excellent enantioselectivities. 12 To the best of our knowledge, the catalytic asymmetric Friedel−Crafts reaction with rac-aziridines as alkylating agents has not been reported until now.…”

Intermolecular Enantioselective Dearomatization Reaction of β‐Naphthol Using meso‐Aziridine: A Bifunctional In Situ Generated Magnesium Catalyst

“…At the outset, we utilized an in situ generated magnesium catalyst,9 including MgBu 2 and quinine ( L1 ; Scheme ) as the chiral ligand, which was reported by us previously 8e. However, the reaction only gave the desired ring‐opening product 3 a with disappointing results (Table 1, entry 1).…”

Magnesium Catalysis in Asymmetric Synthesis

“…In 2014, the Wang group found that this type of catalyst was better able to mediate the Friedel-Crafts reaction of indoles with meso-aziridines (Scheme 37). 80 The reaction hardly occurred with bi-acid ligands, which might be because the indole was not activated because of the weak basicity of the generated oxygen-magnesium bond. The reaction proceeded when a range of mono-acid ligands were utilized.…”