Palladium-Catalyzed Intramolecular Allylic Amidation via Decarboxylative Aromatization: Synthesis of N-Allyl-N-aryl Sulfonamides.

A protocol in the preparation of functionalized N-allyl-N-aryl sulfonamides via palladium-catalyzed intramolecular decarboxylative N-allylation reaction is presented. The alkylated 2,5-cyclohexadienyl ketoesters reacted with arylsulfonamides in the presence of titanium tetrachloride and pyridine, which allows the formation of alkylated 2,5-cyclohexadienyl sulfonyl iminoesters which then undergo a palladium-catalyzed intramolecular allylic amidation through decarboxylative aromatization to provide functionalized N-allyl-N-aryl sulfonamides. This allylation protocol proceeds with good regioselectivity. Moreover, we have also shown that N-allyl-N-aryl sulfonamide can be transformed into 4-aryl-1,2,3,4-tetrahydroquinoline and nitrogen-containing β-hydroxysulfide bioactives.