Synthesis of Thiazinoimidazoles by Lewis Acid-Catalyzed [3+3] Cycloaddition Reactions of Propargyl Alcohols with 2-Mercaptoimidazoles

摘要

The unique ytterbium-catalyzed generation of sulfurand selenium-substituted propargylic and allenic cations and their reactions with 2-mercaptoimidazole derivatives were described. The regioselective [3+3] annulation reactions proceeded to give a wide variety of S,N-acetal-containing bicyclic and tricyclic thiazinoimidazoles in good to high yields. Treatment of thiazinoimidazoles with LDA readily underwent ring contraction to afford thiazolobenzimidazoles. Deselenenylation and successive functionalization broaden the scope of accessible thiazinoimidazoles.