Vinylidene Homologation of Boronic Esters and its Application to the Synthesis of the Proposed Structure of Machillene

James M Fordham, Matthew N Grayson, Varinder Kumar Aggarwal

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1 Citation (Scopus)

Abstract

Alkenyl boronic esters are important reagents in organic synthesis. Herein, we report that these valuable products can be accessed by the homologation of boronic esters with lithiated epoxysilanes. Aliphatic and electron-rich aromatic boronic esters provided vinylidene boronic esters in moderate to high yields, while electron-deficient aromatic and vinyl boronic esters were found to give the corresponding vinyl silane products. Through DFT calculations, this divergence in mechanistic pathway has been rationalized by considering the stabilization of negative charge in the C-Si and C-B bond breaking transition states. This vinylidene homologation was used in a short six-step stereoselective synthesis of the proposed structure of machillene, however, synthetic and reported data were found to be inconsistent.

Original languageEnglish
Pages (from-to)15268-15272
Number of pages5
JournalAngewandte Chemie-International Edition
Volume58
Issue number43
Early online date31 Jul 2019
DOIs
Publication statusPublished - 21 Oct 2019

Keywords

  • homologation
  • natural product
  • organoboron
  • stereospecificity
  • vinyl boronic ester

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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