Formation of Three New Bonds and Two Stereocenters in Acyclic Systems by Zinc-Mediated Enantioselective Alkynylation of Acylsilanes, Brook Rearrangement, and Ene-Allene Carbocyclization Reactions

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• 作者：Polina Smirnov ; Einat Katan ; Jomon Mathew ; Arseni Kostenko ; Miriam Karni ; Anne Nijs ; Carsten Bolm ; Yitzhak Apeloig ; Ilan Marek
• 刊名：Journal of Organic Chemistry
• 出版年：2014
• 出版时间：December 19, 2014
• 年：2014
• 卷：79
• 期：24
• 页码：12122-12135
• 全文大小：884K
• ISSN：1520-6904

文摘

Diastereoisomerically pure (dr > 99:1) and enantiomerically enriched (er up to 98:2) substituted propargyl diols possessing a tertiary hydroxyl group were synthesized in a single-pot operation from simple acylsilanes through a combined catalytic enantioselective alkynylation of acylsilanes, followed by an allenyl-Zn-Brook rearrangement and Zn-ene-allene (or Zn-yne-allene) cyclization reaction. Two remarkable features of these reactions are the near complete transfer of chirality in the allenyl-Zn-Brook rearrangement and the highly organized six-membered transition state of the Zn-ene-allene carbocyclization found by DFT calculations. In this process, three new bonds and two new stereogenic centers are created in a single-pot operation in excellent diastereo- and enantiomeric ratios. DFT calculations show that the allenyl-Zn-Brook rearrangement occurs in preference to the classic [1,2]-Zn-Brook rearrangement owing to its significantly lower activation barrier.