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<p>The catalytic enantioselective [1,2]-Wittig rearrangement of allylic ethers constitutes a recognized synthetic challenge as it is traditionally considered to arise from a non-concerted reaction pathway via formation and recombination of radical pairs. Here we show a catalytic enantioselective solution to this challenge, demonstrating that [1,2]-Wittig products are generated via an alternative reaction cascade to traditional dogma. The developed process employs a chiral bifunctional iminophosphorane catalyst to promote an initial enantioselective [2,3]-sigmatropic rearrangement. A subsequent base-promoted, stereoconvergent, fragmentation–recombination process that proceeds with high enantiospecificity and retention of configuration, formally equivalent to a Woodward–Hoffmann forbidden thermal [1,3]-sigmatropic rearrangement, generates [1,2]-Wittig products in up to 97:3 enantiomeric ratio. Supported by extensive quantum chemistry calculations, this chirality transfer process will have broad implications for fundamental stereocontrol in organic transformations.</p><p></p>

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The catalytic enantioselective [1,2]-Wittig rearrangement cascade of allylic ethers

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月6日

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  • Tengfei Kang,
  • Justin O’Yang,
  • Kevin Kasten,
  • Samuel S. Allsop,
  • Toby Lewis-Atwell,
  • Elliot H. E. Farrar,
  • Martin Juhl,
  • David B. Cordes,
  • Aidan P. McKay,
  • Matthew N. Grayson,
  • Andrew D. Smith

摘要

The catalytic enantioselective [1,2]-Wittig rearrangement of allylic ethers constitutes a recognized synthetic challenge as it is traditionally considered to arise from a non-concerted reaction pathway via formation and recombination of radical pairs. Here we show a catalytic enantioselective solution to this challenge, demonstrating that [1,2]-Wittig products are generated via an alternative reaction cascade to traditional dogma. The developed process employs a chiral bifunctional iminophosphorane catalyst to promote an initial enantioselective [2,3]-sigmatropic rearrangement. A subsequent base-promoted, stereoconvergent, fragmentation–recombination process that proceeds with high enantiospecificity and retention of configuration, formally equivalent to a Woodward–Hoffmann forbidden thermal [1,3]-sigmatropic rearrangement, generates [1,2]-Wittig products in up to 97:3 enantiomeric ratio. Supported by extensive quantum chemistry calculations, this chirality transfer process will have broad implications for fundamental stereocontrol in organic transformations.