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.