Palladium(II)-catalyzed oxidative transformation of allylic alcohols and vinyl ethers into 2-alkoxytetrahydrofurans: catechol as an activator of catalyst.
[chemical reaction: see text]. A highly effective synthesis of 2-alkoxytetrahydrofurans from allylic alcohols and vinyl ethers was achieved by using catalytic amounts of Pd(OAc)2, Cu(OAc)2, and catechol (1:1:2) under O2. The use of catechol as an activator of Pd(II)-Cu(II) catalyst has been unprecedented. The 2-alkoxytetrahydrofurans are formed via oxypalladation of allylic alcohols toward vinyl ethers followed by 5-exo cyclization of the resulting oxypalladation intermediate and subsequent beta-Pd-H elimination. No 6-endo cyclization of the oxypalladation intermediate occurs.
Minami
Kimi
K
Department of Environmental Systems Engineering, Kochi University of Technology, 185 Miyanokuchi, Tosayamada, Kochi, 782-8502, Japan.
Kawamura
Yasufumi
Y
Koga
Koichi
K
Hosokawa
Takahiro
T