Triple ring closing metathesis reaction: synthesis of adjacent cyclic ethers.

[reaction: see text] 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 RuCl(2)(=C(H)Ph)(PCy(3))(2) (Cy = cyclohexyl), and the 1,3-dimesitylimidazol-2-ylidene ruthenium benzylidene catalyst RuCl(2)(=C(H)Ph)(PCy(3))(IMes) ((IMes) = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene). The latter proved to be the most efficient catalyst in these transformations.