Wichterle reaction

What is Wichterle reaction?

The Wichterle reaction, named after Wichterle et al. who first reported it in 1948, is a modified version of the Robinson annulation. Instead of using potentially problematic methyl vinyl ketone, 1,3-dichloro-cis-2-butene is used as an equivalent in the Michael addition step.

Wichterle reaction - general reaction scheme
Wichterle reaction

R = Me, Et, etc.

The resulting γ-chlorocrotyl derivatives are relatively stable and can remain in sulfuric acid H2SO4 for up to a week at room temperature. This reaction is often referred to as the Wichterle reaction and 1,3-dichloro-cis-2-butene is known as the Wichterle reagent. The derivatives can be easily converted to ketones using sulfuric acid H2SO4 or mercury acetate and boron trifluoride etherate in acetic acid before proceeding to the annulation step.

References

Wichterle, O.; Prochazka, J. and Hoffman, J., Coll. Czech. Chem. Commun., 1948, 3, 300

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