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Mild cross metathesis of alkynes
Alkyne metathesis may prove to be as versatile as olefin metathesis, thanks to a catalyst that's been discovered to efficiently promote cross reactions. The molybdenum complex shown, when activated by methylene chloride, promotes cross metathesis reactions of functionalized alkynes that decompose or fail to react with better known catalysts [Org. Lett., 3, 221 (2001)]. In cross reactions, homodimerization of the starting alkynes competes with the desired cross reaction. But according to chemistry professor Alois Fürstner and coworker Christian Mathes at the Max Planck Institute of Coal Research, Mülheim, Germany, the selectivity of the new reagent combination for cross metathesis is excellent. In addition, the researchers were surprised to find that C-silylated alkynes undergo cross reactions smoothly; they report what they believe are the first examples of metathesis reactions involving such starting materials. The mild method tolerates a variety of polar functional groups. And double bonds in the starting materials are not affected.
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