Synthesis of Highly Substituted Pyridines through Copper‐Catalyzed Condensation of Oximes and α,β‐Unsaturated Imines

Abstract

A copper‐catalyzed condensation reaction of oxime acetates and α,β‐unsaturated ketimines to give pyridine derivatives is reported. The reaction features mild conditions, high functional‐group compatibility, and high regioselectivity with respect to unsymmetrical oxime acetates, thus allowing the preparation of a wide range of polysubstituted pyridines, many of which are not readily accessible by conventional condensation methods.

Access to Fully Substituted Dihydropyrimidines via Dual Copper/Photoredox‐Catalyzed Domino Annulation of Oxime Esters and Imines

“…Initially, the excited photocatalyst species Ir(III)* ( E 1/2 (Ir(III)*/Ir(IV))=−1.73 V vs SCE) [21] enables a single‐electron transfer (SET) reduction of 1 a ( E red ( 1 a / 1 a⋅ − )=−1.78 V vs SCE) (see the Supporting Information for details) to deliver iminyl radical A , [4f,g,5,22] which couples with Cu(I) to give Cu(II) intermediate B . The isomerization of B affords Cu(II) species C [8b,9c,13f,18a,b,i] . Nucleophilic addition of C to imine 2 a leads to Cu(II)‐coordinated intermediate D [8b,18b,i] .…”

“…The isomerization of B affords Cu(II) species C [8b,9c,13f,18a,b,i] . Nucleophilic addition of C to imine 2 a leads to Cu(II)‐coordinated intermediate D [8b,18b,i] . The protodemetalation of D affords a secondary amine‐tethered imine E , [18i] which tautomerizes to enamine F .…”

“…Nucleophilic addition of C to imine 2 a leads to Cu(II)‐coordinated intermediate D [8b,18b,i] . The protodemetalation of D affords a secondary amine‐tethered imine E , [18i] which tautomerizes to enamine F . Subsequently, the transimination [23,18i] of F and 2 a takes place to furnish the imine G with the release of PhNH 2 .…”

Sustainable Four-Component Annulation for the Synthesis of 2,3,4,6-Tetraarylpyridines

“…13 More recently, Yoshikai et al reported a coppercatalyzed condensation of oximes and α,β-unsaturated ketimines to afford such pyridines (Scheme 1d). 14 However, the above reactions suffer from one or more drawbacks, such as multistep preparation of starting materials, expensive catalysts, and harsh reaction conditions.…”

A New Avenue to the Synthesis of Symmetrically Substituted Pyridines Catalyzed by Magnetic Nano–Fe3O4: Methyl Arenes as Sustainable Surrogates of Aryl Aldehydes

“…In particular, symmetrically substituted (2,4,6–triaryl) pyridines are important because of their excellent material and biological profiles . The earlier syntheses of 2,4,6–triaryl pyridines involve a reaction between an aldehyde, methyl ketone, and a source of nitrogen . The synthesis of 2,4,6‐triaryl pyridines Yoshikai et al.…”