Efficient synthesis of unsymmetrical heteroaryl thioethers and chalcogenides by alkali hydroxide-mediated S<sub>N</sub>Ar reactions of heteroaryl halides and dichalcogenides
An efficient alkali hydroxide-mediated SNAr reaction of heteroaryl halides has been developed for the practical synthesis of the useful unsymmetrical heteroaryl thioethers and chalcogenides. The usually odorless, easily available, lowly toxic, and easily stored and handled diorganyl dichalcogenides can be used as safer and convenient chalcogen nucleophile precursors and diverse unsymmetrical heteroaryl
Sulfur–silicon bond activation catalysed by Cl/Br ions: waste-free synthesis of unsymmetrical thioethers by replacing fluoride catalysis and fluorinated substrates in SNAr reactions
In contrast to conventional activation of NuâSiR3 reagents by F ion attributed to the strong affinity of Si to F, SâSi activation can now be achieved using Cl/Br ions of TBAX as catalysts via formation of weaker XâSi bonds and Me3SiâX. This led to a waste-free synthesis of unsymmetrical thioethers via F-free SNAr reactions of activated (hetero)aryl halides and RSâSiMe3, with recovery of the useful Me3SiâX reagent in high yields.
Green Chemical Synthesis of 2-Benzenesulfonyl-pyridine and Related Derivatives
作者:William G. Trankle、Michael E. Kopach
DOI:10.1021/op700060e
日期:2007.9.1
A practical synthesis of 2-benzenesulfonylpyridine, 1, is described which is a key starting material for the manufacture of an investigational new drug candidate at Eli Lilly and Company. An optimized green chemical process was developed which features a novel tandem SNAr/oxidation under mild conditions to produce the target sulfone, 1, in 86% yield and >99% purity. In addition, this novel, environmentally friendly methodology was found to be general for the synthesis of substituted aromatic pyridyl sulfides and sulfones.