Grignard-Reagent-Promoted Desulfonylation/Intramolecular Coupling for the Synthesis of 2-(1-Fluorovinyl)pyridines
A novel process involving Grignard-reagent-promoted desulfonylation/intramolecular coupling of readily available α-fluoro-α,β-unsaturated-(2-pyridyl)sulfones was realized that provided a series of polysubstituted 2-(1-fluorovinyl)pyridines in good yields. The intrinsic coordination between pyridine and Mg(II) along with the "negative fluorine effect"of the substrates should play the key role for the smooth transformation in the absence of transition-metal catalysts.
Synthesis and characterization of 2-pyridylsulfur pentafluorides
Current approaches to prepare SF5-substituted heterocycles during the synthesis of targeted heterocyclic compounds require the use of SF5-functionalized aryl or alkyne reagents or SF5Cl as a source of the SF5 functional group. Herein we report that excess oxidative fluorination of 2,2' -dipyridyl disulfide with a KF/Cl2 /MeCN system leads to the formation of thirteen new 2-pyridylsulfur chlorotetrafluorides (2-SF4Cl-pyridines). These molecules are found to undergo further chlorine-fluorine exchange reactions by treatment with silver(I) fluoride enabling ready access to a series of ten new substituted 2-pyridylsulfur pentafluorides (2-SF5-pyridines). This is the first preparatively simple and readily scalable example of the transformation of an existing heterocyclic sulfur functionality to prepare SF5-substituted heterocycles.
Kanishchev, Oleksandr S.,Dolbier, William R.
supporting information
p. 280 - 284
(2015/04/21)
Deoxydative Thiation of 3-Substituted Pyridine N-Oxides with 4-Methoxytoluene-α-thiol: A Divergent Route to Pyridinethiols
Synthesis of 3-substituted 2-pyridinethiols was achieved by thiation of pyridine N-oxides with 4-methoxytoluene-α-thiol in the presence of diethylcarbamoyl chloride followed by cleavage of the resulting sulfides.The case of substitution was shown to be affected by nucleophilicity of the N-oxide oxygen.Addition of zinc bromide to the reaction, a need for triethylamine, decreased most of the yield for thiation products but the formation of 3-methoxy-2-methoxybenzylthiopyridine was only improved.A plausible mechanism of the substitution, particularly β-thiation to the N-oxide function, is discussed compared with the regiochemistry observed in the reaction with diethoxyphosphoryl chloride instead of diethylcarbamoyl chloride.The debenzylation to pyridinethiol was also found to be dependent on the electron-density in the pyridine ring.
Sato, Nobuhiro,Nagano, Eiichi
p. 691 - 698
(2007/10/02)
More Articles about upstream products of 5897-94-9