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

Abstract

A one-pot, four-component annulation of 2,3,4,6-tetraarylpyridines from aromatic aldehydes, methyl ketones, diaryl ethanones, and ammonium acetate is described. The reaction features high functional group compatibility in air under solvent-free conditions without any additive and only water as the nontoxic byproduct, providing a strategy for the facile, economical, and eco-friendly construction of multiaryl-substituted pyridines from simple and readily available reactants.

Recent Advances in Synthesis of Multiply Arylated/Alkylated Pyridines

“…Unsymmetrical pyridines 54 can be synthesized by using more reactive acetophenones to facilitate the synthesis of versatile polysubstituted pyridines 54 under solvent‐free conditions (Scheme 30). [44] The electron‐rich aldehyde exhibits lower reactivity in this reaction, which requires a higher reaction temperature to obtain the corresponding pyridine in a comparable yield.…”

Recent Advances in Synthetic Routes to Azacycles

“…Several studies have succeeded in synthesizing or functionalizing azacycle compounds. In addition, several methods of synthesis for aromatic azacycles have been reported [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. However, these methods still have several drawbacks such as being time-consuming, requiring a high temperature, expensive additives, and/or organic solvents, and/or having low chemoselectivity properties [ 61 , 62 , 63 ].…”

Regioselective Hydrodeoxygenation of α-Diketones with Phosphites under Visible-Light Catalysis

“…We envision that through careful tailoring, this photoredox platform could render us varied carbene-based deoxygenative functionalization strategies and provide access to a variety of valued molecules that are of medicinal or industrial interests. As a proof of concept, herein, we report a visible-light-catalyzed chemoselective hydrodeoxygenation of α-diketones via HAT of the intermediate α-ketocarbenes, which gives 1,2-diarylethanones that are especially useful materials for synthesizing heterocycles …”