Facile Preparation of Indoles and 1,2-Behzothiazine 1,1-Dioxides: Nucleophilic Addition of Sulfonamides to Bromoacetylenes and Subsequent Palladium-Catalyzed Cyclization

摘要

Nucleophilic addition to an electron-deficient carbon-carbon multiple bond is one of the most fundamental reactions in organic chemistry. Among the various electron-withdrawing groups adjacent to an olefin or acetylene, thus making this process feasible, the weakest possible substituents, such as halogens, have recently attracted increasing attention. We have already reported that certain nitrogen-containing compounds such as N-alkylsulfonamides, imidazolines, or imidazoles undergo nucleophilic addition to l-halo-l-alkynes. Furthermore, the synthetic utility of the adducts obtained by this reaction has been explored in a cyclization reaction affording nitrogen heterocycles.