special topic	Synthesis 2000; 2000: 899-903 DOI: 10.1055/s-2000-6268
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An Efficient Strategy for the Synthesis of α,α′-cis and trans-Disubstituted Medium Ring Ethers
Michael T. Crimmins*, Kyle A. Emmitte
*Venable and Kenan Laboratories of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA; Fax +1 (9 19) 9 62 23 88; E-mail: crimmins@email.unc.edu

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.

asymmetric-alkylation - ring-closing metathesis - marine natural products - gauche effect - cyclic ethers - ruthenium