RESUMEN
Bromine as a double agent: The bromine atom in 1-bromo-1-alkynes works as an electron-withdrawing group to effect the nucleophilic addition of sulfonamides. It again plays a pivotal role in the palladium-catalyzed cyclization of the resultant (Z)-2-(sulfonylamino)-1-bromoalkenes into nitrogen heterocycles (see scheme).
Asunto(s)
Alquinos/química , Bromo/química , Indoles/síntesis química , Óxidos/síntesis química , Paladio/química , Sulfonamidas/química , Tiazinas/química , Catálisis , Ciclización , Compuestos Heterocíclicos/química , Estructura MolecularRESUMEN
Nucleophilic addition of imidazolines to 1-halo-1-alkynes takes place by simple heating in DMF without any additives to give (Z)-N-(1-halo-1-alken-2-yl)imidazolines in good yield and in a highly regio- and stereoselective manner. These reaction conditions are also valid for the similar addition of imidazoles.
Asunto(s)
Acetileno/química , Bromo/química , Cloro/química , Imidazoles/química , Imidazolinas/química , Yodo/química , Estructura Molecular , EstereoisomerismoRESUMEN
Nucleophilic addition of sulfonamides to 1-bromo-1-alkynes provided (Z)-N-(1-bromo-1-alken-2-yl)-p-toluenesulfonamides in good yield and in a highly regio- and stereoselective manner. Treatment of product (Z)-N-(1-bromo-1-octen-2-yl)-N-allyl-p-toluenesulfonamide with a palladium catalyst under Heck conditions afforded 1-(p-toluenesulfonyl)-2-hexyl-4-methylpyrrole in good yield. Other pyrroles with various substituents can also be prepared in good yield by this method.