Iodine-Catalyzed Intramolecular Thiolation Of Vinylic Carbon-Hydrogen Construction Of 2-Methylene-3-thiophenones

In the field of organic sulfur chemistry, a-oxo ketene dithioacetals are siginificant organic synthesis intermediates. They have a plurality of reactive, and it can occur many types of reactions. So they are widely applied to the synthesis of variousl organic compounds.As we all known C-S bond coupling has a very important significance in organic synthesis and medicinal chemistry. Many drug and biologically activity molecules containing C-S bonds, therefore, focus on the content of the formation of the C-S bond is our research group study. In Organic Chemistry, many sulfur-containing heterocyclic compounds have been prepared by carbon-sulfur bond formation. So construction of novel sulfur-containing heterocyclic compound is an important task.Iodine is low toxicity, environmental friendly, so it has widely used in organic synthesis. Iodine can be used as electrophilic inducers for inducers for alkenes and alkynes electrophiliccyclization reaction, in order to construct the lactione, lactam compounds. This paper selected a-alkenoyl ketene dithioacetals as a kind of multifunctional olefin. Under the catalysis of iodine(10 mol %), the cyclization of a-alkenoyl ketene dithioacetals afforded a broad range of polyfunctionalized 2-methylene-3-thiophenones in good selectivity with moderate to excellent yields via tandem iodocyclization and dehydroiodination. The synthetic strategy can also be extended to the cyclization of 1-(2-(methylthio) phenyl)-2-en-1-one leading to 2-methylene-3-benzothiophenones. This work provides a new method for synthesis of thiophenones.