Enantioselective Cyclobutenylation of Olefins Using N-Sulfonyl-1,2,3-Triazoles as Vicinal Dicarbene Equivalents

Org Lett. 2021 Aug 20;23(16):6530-6535. doi: 10.1021/acs.orglett.1c02331. Epub 2021 Aug 10.

Abstract

Cyclobutenes are highly useful synthetic intermediates as well as important motifs in bioactive small molecules. Herein, we report a regio-, chemo-, and enantioselective synthesis of cyclobutenes from olefins using N-sulfonyl-1,2,3-triazoles as vicinal dicarbene equivalents or alkyne [2 + 2] cycloaddition surrogates. Terminal and cis-olefins can be transformed into enantioenriched cyclopropanes via rhodium catalysis. Then, in one pot, treatment of these intermediates with tosyl hydrazide and base effects diazo formation followed by rhodium-catalyzed ring expansion to yield enantioenriched cyclobutenes. These cyclobutenes can be transformed into highly substituted, enantioenriched cyclobutanes, including structures relevant to natural product scaffolds.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkenes / chemistry*
  • Alkynes / chemistry*
  • Catalysis
  • Cycloaddition Reaction
  • Cyclobutanes / chemistry*
  • Cyclopropanes / chemistry*
  • Molecular Structure
  • Rhodium / chemistry
  • Stereoisomerism
  • Triazoles / chemistry*

Substances

  • Alkenes
  • Alkynes
  • Cyclobutanes
  • Cyclopropanes
  • Triazoles
  • Rhodium