39161-56-3Relevant articles and documents
Sustainable Four-Component Annulation for the Synthesis of 2,3,4,6-Tetraarylpyridines
Ding, Yuxin,Ma, Renchao,Xiao, Xu-Qiong,Wang, Lei,Wang, Zhiming,Ma, Yongmin
, p. 3897 - 3906 (2021/03/09)
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.
N-Silylenamines as Reactive Intermediates: Hydroamination for the Modular Synthesis of Selectively Substituted Pyridines
Lui, Erica K. J.,Hergesell, Daniel,Schafer, Laurel L.
supporting information, p. 6663 - 6667 (2018/11/21)
A modular and selective synthesis of mono-, di-, tri-, tetra-, and pentasubstituted pyridines is reported. Hydroamination of alkynes with N-silylamine using a bis(amidate)bis(amido)titanium(IV) precatalyst furnishes the regioselective formation of N-silylenamines. Addition of α,β-unsaturated carbonyls to the crude mixtures followed by oxidation affords 47 examples of pyridines in yields of up to 96%. This synthetic route allows for the synthesis of diverse pyridines containing variable substitution patterns, including pharmaceutically relevant 2,4,5-trisubstituted pyridines, using this one-pot protocol.
Synthesis of Highly Substituted Pyridines through Copper-Catalyzed Condensation of Oximes and α,β-Unsaturated Imines
Tan, Wei Wen,Ong, Yew Jin,Yoshikai, Naohiko
supporting information, p. 8240 - 8244 (2017/06/30)
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.
On the Mechanism of the Thermal Conversion of Cyclopropenyl-Substituted Oxazolinones to Pyridines
Padwa, Albert,Cohen, Leslie A.,Gingrich, Henry L.
, p. 1065 - 1073 (2007/10/02)
Thermolysis or photolysis of a sample of a 3-cyclopropenyl-substituted 2H-azirine produced 2-methyl-3,4,5,6-tetraphenylpyridine in high yield.The reaction can best be rationalized by a mechanism involving formation of a nitrile ylide intermediate followed by intramolecular dipolar cycloaddition to give an azabenzvalene, which subsequently rearranges to the pyridine.The thermal chemistry of a series of cyclopropenyl-substituted oxazolinones was also investigated.These oxazolinones undergo a thermally induced 1,3-dipolar cycloreversion reaction with elimination ofcarbon dioxide to generate a nitrile ylide intermediate adjacent to the cyclopropene ring.This dipole can be trapped when the thermolysis of the oxazolinone was carried out in the presence of a reactive dipolarophile.Heating a sample of 2-phenyl-4-methyl-4-(1-methyl-2,3-diphenyl-2-cyclopropen-1-yl)-Δ2-oxazolin-5-one at 150 deg C for 24 h afforded a mixture of 2,3-dimethyltriphenylpyridine (45percent), 2,4-dimethyltriphenylpyridine (20percent), and 2,5-dimethyltriphenylpyridine (35percent).The formation of these products is proposed to involve a stepwise cycloaddition of the initially generated nitrile ylide to produce a bicyclobutyl zwitterion which can either collapse to give an azabenzvalene or undergo rearrangement to a cyclobutenyl cation. This latter species closes to produce two different aza Dewar benzenes.Reorganization of the azabenzvalene and aza Dewar benzenes gives rise to the observed pyridines.Alternate mechanisms based on a concerted intramolecular cycloaddition reaction of the nitrile ylide do not account for the observed product ratios.
