Stereochemical investigations of the Tetrahymena cyclase, a model system for euphane/tirucallane biosynthesis.

  title={Stereochemical investigations of the Tetrahymena cyclase, a model system for euphane/tirucallane biosynthesis.},
  author={Jos{\'e}-Luis Giner and Ju Feng},
  journal={Organic \& biomolecular chemistry},
  volume={15 13},
  • J. Giner, Ju Feng
  • Published 28 March 2017
  • Chemistry, Biology
  • Organic & biomolecular chemistry
The squalene cyclase of Tetrahymena pyriformis cyclizes 2,3-dihydrosqualene to euph-7-ene. This was used as a model for euphane biosynthesis. D-ring formation was demonstrated to involve pre-chair folding through an experiment with 2,3-dihydro-5-oxasqualene. This requires that a non-least motion rotation (120°) of the C17-20 bond in the intermediate deoxydammaranyl cation occurs before the first 1,2-hydride shift. Truncated substrates relieved the hindrance associated with this rotation and… 
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It is proposed that their biosynthesis involves an epoxysqualene cyclase which can carry out both all‐chair and B‐boat cyclizations.


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