From Silylated Trishomoallylic Alcohols to Dioxaspiroundecanes or Oxocanes: Catalyst and Substitution Influence.

A versatile method for the synthesis of dioxaspiroundecanes through a tandem Sakurai-Prins cyclization of allylsilyl alcohols in the presence of TMSOTf is described. The process is general and highly stereoselective with total control in the creation of three new stereogenic centers in a single step. Moreover, a very interesting chemoselectivity has been observed depending on the nature of the catalyst used or the substitution of the trishomoallylic alcohol, since the same reaction under BF3·OEt2 catalysis or using alcohols with allylic substituents provides exclusively the corresponding oxocanes, by a direct silyl-Prins cyclization.