Stereoselective Synthesis of Bicyclo[4.2.1]nonane Skeletons by Ring-Closing Metathesis: A New Versatile Methodology for the Efficient Assembly of Functionalized Cyclooctanoids

摘要

A new versatile methodology, resulting in a formal three-carbon ring expansion of cyclopentanones, for the efficient assembly of functionalized cyclooctanoids is described. The approach is based on the chemo-, regio-, and stereoselective α,γ-difunctionalization of β-ketoesters followed by ring-closing metathesis to form functionalized bicyclo[4.2.1]nonanes, precursors of the corresponding cyclooctanes, by selective ring cleavage of the one-carbon-atom bridge.