Cycloisomerization of allene-enol ethers under Bi(OTf)3 catalysis.

The cycloisomerization of allene-enol ethers under Bi(OTf)3 catalysis was developed as a novel "atom-economic" tool for accessing interesting functionalized cyclopentene rings. Bi(OTf)3 was shown to promote selectively the activation of the enol ether moiety of the substrate. This catalytic methodology was further extended to the synthesis of dihydrofuran and oxaspirocycle derivatives.

Metal-triflate-catalyzed synthesis of polycyclic tertiary alcohols by cyclization of γ-allenic ketones.

It has been established that bismuth(III) triflate catalyzes the cyclization of γ-allenic ketones under mild reaction conditions. This reaction allows the selective formation of polycyclic tertiary alcohols from cyclic ketone derivatives. The resulting dienols can engage in stereoselective cycloadditions to efficiently afford complex polycyclic systems.