Gold-Catalyzed Synthesis of THFs and Pyrrolidines by Oxidative Coupling

Significance

Reported is the synthesis of tetra­hydrofurans and pyrrolidines 3 via a gold-catalyzed oxidative cross-coupling. The reaction is tolerant of substituted pent-4-en-1-ols, including primary and tertiary alcohols. In general, N-tosyl pent-4-en-1-amines proved superior substrates giving pyrrolidines 3 in good to excellent yields. Weakly or strongly activated arylboronic acids participated efficiently in the reaction. In contrast, poor yields were obtained using electron-rich boronic acids, most likely due to incompatibility with Selectfluor. Disappointingly, internal alkenes were found to be inert under the reaction conditions. Six-membered heterocycles 5 and 6 were also prepared using this method, although the yield of tetrahydropyran 5 was poor.