Catalytic Asymmetric Friedel–Crafts/Protonation of Nitroalkenes and N-Heteroaromatics

Abstract

The catalytic asymmetric Friedel-Crafts/protonation of indoles and pyrroles with α-substituted nitroalkenes to give the corresponding adducts in a highly anti-selective manner was achieved by an imidazoline-aminophenol (L2)-Cu complex. The anti-adducts could be successfully transformed to biochemically important α-substituted β-heteroarylalkylamines.

Diastereoselective Isomerization of (E)‐β‐Nitroenones into β‐Nitro‐β,γ‐Unsaturated Ketones under Microwave Conditions

“…[1][2][3] In this context, β-nitroenones 1 are an emerging class of polyfunctionalized nitroalkenes, which over the years have proven to be valuable starting materials for the preparation of small molecules and heterocyclic systems such as 1,4-diketones, β-nitroketones, unsaturated systems, furans, pyrrole and indole derivatives (Scheme 2). [4] Following our studies on this class of molecules, we have now found an unprecedented isomerization of (E)-1 derivatives, which selectively convert into unconjugated β-nitro-β,γ-unsaturated ketones 2 under microwave conditions (Scheme 3).…”

Chiral Imidazoline Ligands and Their Applications in Metal‐Catalyzed Asymmetric Synthesis†

“…[ 120 ] The ligands were proposed to be tridentate with the UV evidence of a phenoxide group. [ 122 ] And the crystal structure of Ni/IAP complex was elucidated in 2014, providing solid evidence of a tridentate coordinating manner. [ 127 ] Ligand IAP2 forms a 2 : 1 complex Ni(IAP) 2 with Ni 2+ , and the length of Ni—O bond is shorter than Ni—N bond, which further supported the tridentate manner.…”

β‐Nitroacrylates: A Versatile and Growing Class of Functionalized Nitroalkenes

“…The Friedel–Crafts reaction between indoles or pyrroles and β‐nitroacrylates was explored by Aray et al. for generating chiral α‐substituted β‐heteroarylalkylamines, the leitmotif of many biologically active compounds . In particular, the F‐C reaction was investigated using copper(I) triflate in the presence of the imidazoline aminophenol ligand L 5 or L 6 , with identification of L 5 as the more effective one (Scheme ).…”