Selective Boryl-Anion Migration in a Vinyl sp2−sp3 Diborane Induced by Soft Borane Lewis Acids

Valerio Fasano, Jessica Cid, Richard J. Procter, Emily Ross, Michael J. Ingleson

Research output: Contribution to journalArticlepeer-review

Abstract

An intramolecular 1,2-boryl-anion migration from boron to carbon has been achieved by selective activation of the π system in [(vinyl)B2Pin2)] using “soft” BR3 electrophiles (BR3=BPh3 or 9-aryl-BBN). The soft character is key to ensure 1,2-migration proceeds instead of oxygen coordination/B−O activation. The BR3-induced 1,2-boryl-anion migration represents a triple borylation of a vinyl Grignard reagent using only B2Pin2 and BR3 and forms differentially protected 1,1,2-triborylated alkanes. Notably, by increasing the steric bulk at the β position of the vinyl Grignard reagent used to activate B2Pin2, 1,2-boryl-anion migration can be suppressed in favor of intermolecular {BPin} transfer to BPh3, thus enabling simple access to unsymmetrical sp2−sp3 diboranes.

Original languageEnglish
Pages (from-to)13293-13297
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number40
Early online date13 Aug 2018
DOIs
Publication statusE-pub ahead of print - 13 Aug 2018

Keywords

  • 1,2-migration
  • boranes
  • borylation
  • Grignard reagents
  • Lewis acids

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