Zr-Catalyzed Kinetic Resolution of Aliphatic Cyclic Allylic Ethers. Carbocycles to Heterocycles by Ru- and Mo-Catalyzed Ring-Opening and Ring-Closing Metathesis

The Zr-catalyzed kinetic resolution of aliphatic allylic ethers derived from five-, six-, seven-, and eight-membered ring allylic alcohols is reported. The level of resolution efficiency varies as a function of ring size and substitution pattern of the pendant alkene. The metal-catalyzed transformation of the above unsaturated ethers to dihydrofurans is also disclosed. Seven- and eight-membered ring substrates are readily converted to furans in the presence of 10 mol % Ru catalyst 16. In contrast, the less reactive cyclopentenol systems demand the more potent Mo-based metathesis catalyst 3. The selectivity and reactivity patterns in the Zr-catalyzed process and the Ru- or Mo-catalyzed reactions differ from the previously reported reactions of the related styrenyl ethers.