Synthesis of Oxazolidinones from Epoxides and Isocyanates Catalysed by Aluminium Heteroscorpionate Complexes

José A. Castro-Osma*, Amy Earlam, Agustín Lara-Sánchez, Antonio Otero, Michael North

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The combination of an aluminium(heteroscorpionate) complex and tetrabutylammonium bromide acts as a highly efficient catalyst system for the synthesis of oxazolidinones from epoxides and isocyanates. Twenty two complexes were tested derived from a range of bispyrazole ligands and containing 1-3 aluminium atoms per complex. The optimal catalyst was found to be a bimetallic complex of a thioacetamidate ligand. Under the optimal reaction conditions (80°C in toluene for 24h using 5mol% of both aluminium catalyst and tetrabutylammonium bromide co-catalyst), six epoxides were reacted with six aromatic isocyanates, giving 25 oxazolidinones in moderate to excellent yields showing broad substrate scope. The regiochemistry of the reaction (to produce 3,4- or 3,5-oxazolidinones) is controlled by the substrate with epoxide ring opening occurring preferentially at the less hindered end of the epoxide unless a substituent on the epoxide can stabilise a positive charge.

Original languageEnglish
Pages (from-to)2100–2108
Number of pages9
JournalChemCatChem
Volume8
Issue number12
DOIs
Publication statusPublished - 30 May 2016

Bibliographical note

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Keywords

  • Aluminium
  • Heterocycles
  • Homogeneous catalysis
  • Ligand effects
  • Regioselectivity

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