Construction of 2,2-Dimethyloxepane Frameworks from Ene-Diols Catalyzed by Metal Catalyst or Bronsted Acid via 7-Endo-Trig Cyclization

The synthesis of 2,2-dimethyloxepane frameworks based on the 7-endo-trig cyclization of ene-diol using a catalytic amount of metal catalysts (Au, Ag) or Brensted acid (TfOH) has been developed. Also, the Spiro-type dioxabicyclic products were also derived from the diene-diols. For the condition using metal catalysts, the cyclization selectively reacted between the 1,1,3-trisubstituted alkenes and alcohols to form the 2,2-dimethyloxepane frameworks. On the other hand, the TfOH reacted with not only the 1,1,2-trisubstituted alkene, but also the 1-substituted and 1,2-disubstituted alkenes providing the corresponding cyclic ethers, which is quite different from the conditions of the metal catalysts.

Automated summary

The synthesis of 2,2-dimethyloxepane frameworks via the 7-endo-trig cyclization of ene-diol using metal catalysts or Brønsted acid has been developed. Metal catalysts selectively react between 1,1,3-trisubstituted alkenes and alcohols, while Brønsted acid reacts with a variety of alkene types providing different cyclic ethers.