The Danheiser annulation or Danheiser TMS-cyclopentene annulation is an organic reaction of an α,β-unsaturated ketone and a trialkylsilylallene (e.g., trimethylsilyl- or triisopropylsilyl-) in the presence of a Lewis Acid to give a trialkylsilylcyclopentene in a regiocontrolled annulation.
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Danheiser annulation Wikipedia(Text) CC BY-SA