An efficient strategy for the synthesis of α,α'-cis and trans- disubstituted medium ring ethers

An asymmetric alkylation-ring-closing metathesis strategy was developed for the construction of α,α'-disubstituted medium ring ethers. The approach features an asymmetric alkylation of highly functionalized α-alkoxy acyl oxazolidinones followed by ring closure effected by Grubbs' ruthenium catalyst. The relationship between diene conformation and the rate of ring- closure was examined.