Triple ring closing metathesis reaction: Synthesis of adjacent cyclic ethers

Adjacent tris(cyclic ethers) and enol ethers have been synthesized in good yields for the first time via a triple olefin metathesis reaction using Grubbs' catalyst RuCl2(double bondC(H)Ph)(PCy3)(2) (Cy = cyclohexyl), and the 1,3-dimesitylimidazol-2-ylidene ruthenium benzylidene catalyst RuCl2(double bondC(H)Ph)(PCy3)(IMes) ((IMes) = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene). The latter proved to be the most efficient catalyst in these transformations.