Use of 1,3-dipolar reactions for the preparation of SF5-substituted five-membered ring heterocycles. Pyrroles and thiophenes

In situ-generated unsubstituted, “parent” azomethine and thiocarbonyl ylides are used to prepare a large variety of 3-aryl- and alkyl-substituted, 4-pentafluorosulfanylpyrroles and 3-aryl-substituted, 4-pentafluorosulfanylthiophenes, the latter of which are to our knowledge the first reported SF5-substituted thiophenes. The 1,3-cycloadditions of these ylides with aryl and alkyl, SF5-alkynes produce dihydro-pyrroles and thiophenes, which without isolation can then be oxidatively aromatized to the respective pentafluorosulfanylpyrroles and thiophenes in good yield.

Synthesis of pentafluorosulfanyl pyrroles and thiophenes via 1,3-dipolar cycloadditions of azomethine ylide and thiocarbonyl ylide.Figure optionsDownload as PowerPoint slideHighlights
► Synthesis of pentafluorosulfanyl pyrroles.
► Synthesis of pentafluorosulfanyl thiophenes.
► 1,3-Dipolar cycloadditions of thiocarbonyl ylide.
► 1,3-Dipolar cycloadditions of azomethine ylide.