875228-76-5

Upstream product

• 856834-57-6 6-chloro-3-methyl-2,4-diphenyl-pyridine 
• 5409-66-5 3-benzoyl-4-hydroxy-1-methyl-4-phenylpiperidine 
• 7664-93-9 sulfuric acid 
• 5409-66-5 3-benzoyl-4-hydroxy-1-methyl-4-phenylpiperidine 
• 108-24-7 acetic anhydride 
• 1426021-96-6 (E)-1-phenylpropan-1-one O-acetyl oxime 
• 104-55-2 3-phenyl-propenal 
• 133145-92-3 1-phenylpropan-1-one O-acetyl oxime 
• 4258-37-1 1,3-diphenyl-2-methylpropene-3-one 
• 13721-15-8 3-benzoyl-1-ethyl-4-phenyl-4-hydroxypiperidine 

Relevant academic research and scientific papers

Synthesis of polysubstituted pyridines from oxime acetates using NH4I as a dual-function promoter

Pyridine formation with oxime acetates as the building blocks under metal-free conditions is described. Ammonium iodide has proved to be a highly efficient promoter for oxime N-O bond reduction and subsequent condensation reactions, whereby it played a dual-function role in the transformation. While the three-component reaction of oxime acetates, benzaldehydes, and 1,3-dicarbonyls proceeded well with the assistance of a stoichiometric amount of ammonium iodide, the condensation of oximes and acroleins was enabled by using a catalytic initiator to afford substituted pyridines. By this protocol, substituted pyridine products were generated in moderate to excellent yields with tolerance towards a broad range of functional groups.

Route to Highly Substituted Pyridines

Pyridine rings are common structural motifs found in a number of biologically active compounds, including some top-selling pharmaceuticals. We have developed a new approach to access substituted pyridines. The method aims to provide a reliable synthesis of a diverse range of substituted pyridines through a three-step procedure. Readily available enones are first converted into 1,5-dicarbonyls through a two-step Hosomi-Sakurai allylation/oxidative cleavage sequence, which is followed by subsequent cyclization to the corresponding pyridine using hydroxylamine hydrochloride. A variety of substituted pyridines have been synthesized using this method.

Metal-Free Assembly of Polysubstituted Pyridines from Oximes and Acroleins

Transition-metal-catalyzed synthesis of N-heterocycles from oximes has been previously well established. In this paper, for the first time a metal-free protocol with the combinational employment of iodine and triethylamine has been demonstrated to be effective to trigger the oxime-based synthesis of pyridines with high chemo-selectivity and wide functional group tolerance. A broad range of functional pyridines were prepared in moderate to excellent yields. While neither iodine nor triethylamine could trigger this transformation, mechanistic experiments indicated a radical pathway for the reaction. The resultant 2-aryl-substituted pyridines have been proved to be versatile building blocks in a range of transition-metal-catalyzed C-H functionalization reactions. (Chemical Equation Presented).

Modular pyridine synthesis from oximes and enals through synergistic copper/iminium catalysis

We describe here a [3+3]-type condensation reaction of O-acetyl ketoximes and α,β-unsaturated aldehydes that is synergistically catalyzed by a copper(I) salt and a secondary ammonium salt (or amine). This redox-neutral reaction allows modular synthesis of a variety of substituted pyridines under mild conditions with tolerance of a broad range of functional groups. The reaction is driven by a merger of iminium catalysis and redox activity of the copper catalyst, which would initially reduce the oxime N-O bond to generate a nucleophilic copper(II) enamide and later oxidize a dihydropyridine intermediate to the pyridine product.