Catalyst-controlled ring-opening cycloisomerization reactions of cyclopropenyl carboxylates for highly regioselective synthesis of different 2-alkoxyfurans.

Differently substituted 2-alkoxyfurans (2,3,4- or 2,3,5-trisubstituted furans) were highly regioselectively synthesized by means of the ring-opening cycloisomerization of the same cyclopropenyl carboxylates with good yields in different solvents and excellent regioselectivity by using [Cu(acac)(2)] (acac=acetylacetonate) or [RuCl(2)(PPh(3))(3)] as the catalyst, respectively. The structures of these two different types of furans were established by X-ray diffraction studies. A rationale has been proposed.