Propargyl Claisen Rearrangement

By: Josephine Nakhla, Chemfiles Volume 10 Article 4

Toste and coworkers reported the use of the gold catalyst [(Ph3PAu)3O]BF4 for the rapid two-step, one-pot sequence of a Claisen rearrangement of a propargyl vinyl ether followed by a reduction of the resulting aldehyde functionality to provide a variety of homoallenic alcohols. The reactions are generally high yielding and the robust catalyst system is able to induce almost complete chirality transfer (in most cases, ee’s were >90%). Low catalyst loadings (1 mol %) and substitution at the alkyne is well tolerated generating the desired allenes in high yields (Scheme 3).

Scheme 3: Preparation of homoallenic alcohols via Claisen rearrangement/ reduction sequence


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References

  1. Sherry, B. S.; Toste, F. D. J. Am. Chem. Soc. 2004, 126, 15978.

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