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Synlett 2018; 29(13): 1753-1758
DOI: 10.1055/s-0037-1610454
letter
© Georg Thieme Verlag Stuttgart · New York

A Straightforward Access to Trifluoromethylated Spirobipyrazolines through a Double (3+2)-Cycloaddition of Fluorinated Nitrile Imines with Alkoxyallenes

Greta Utecht
,
Grzegorz Mlostoń
,
Marcin Jasiński*
The authors thank the National Science Center (NCN, Poland) for ­financial support in the framework of Preludium grant #2016/21/N/ST5/01254.
Further Information

Publication History

Received: 24 April 2018

Accepted after revision: 29 May 2018

Publication Date:
02 July 2018 (online)

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Dedicated to Professor Janusz Zakrzewski (University of Łódź) on the occasion of his 70th birthday

Abstract

Formal double (3+2)-cycloaddition of in situ generated tri­fluoroacetonitrile imines with alkoxyallenes proceeds in a highly regio- and diastereoselective manner to afford anti-configured spirobipyrazolines as the exclusive 2:1 adducts. Initial stepwise addition of the title electron-deficient 1,3-dipoles onto cumulenic reaction partner is pos­tulated to explain the observed reaction pathway.

Key words

nitrile imines - alkoxyallenes - (3+2)-cyclo­addition - pyrazolines - spiro compounds

Supporting Information

    Supporting information for this article is available online at https://doi.org/10.1055/s-0037-1610454.
  • Supporting Information
 

  • References and Notes


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