Highly Diastereoselective Michael Additions onto Dienyl Bis-Sulfoxides

Abstract

An optimized procedure for the preparation of (S _S,S _S)-bis(p-tolylsulfinyl)methane (4) is reported. Condensation of the lithium salt of 4 onto cinnamaldehyde furnished bis-sulfoxide dienyl derivative 5, a remarkable 1,4-Michael acceptor that can lead in a highly dia­stereoselective manner to vinylcyclopropyl adducts. In a chelating mode of reactivity using a methylcopper reagent, a complete reversal of stereoselectivity is observed giving an enantiopure β,γ-unsaturated methyl ester intermediate that is used in the synthesis of cryptophycin.

bis-sulfoxide - Michael addition - vinylcyclopropane - cryptophycin

References

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