Efficient Isomerization of α-Pinene Oxide to Campholenic Aldehyde Promoted by a Mixed-Ring Analogue of Molybdenocene

Sofia M. Bruno, Anabela A. Valente, Martyn Pillinger, Jeffrey Amelse, Carlos C. Romão, Isabel S. Gonçalves

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

The MoIV complex [(η5-indenyl)( η5-cyclopentadienyl)Mo(MeCN)2](BF4)2 (1) has been used to promote two acid-catalyzed epoxide ring-opening reactions under ambient conditions. The alcoholysis of styrene oxide in neat ethanol gave 2-ethoxy-2-phenylethanol in quantitative yield within 10 min. The use of an ionic liquid (IL) as a cosolvent benefitted catalyst solubility and recycling while not impairing catalytic performance. Complex 1 in 1,2-dichloroethane was effective for the isomerization of α-pinene oxide to campholenic aldehyde (CPA), leading to 87% yield at 1 h of reaction. The same yield could be achieved within 1 min by using the IL [Choline][NTf2] as a solvent. CPA yields at 1 min reached near-quantitative values (98%) upon recycling of the catalyst/IL mixture, demonstrating an unparalleled combination of activity, selectivity and recyclability for this commercially important reaction. Considering the catalytic features of the 1/IL system, a CPA process flow diagram is proposed and compared to patented technology.

Original languageEnglish
Pages (from-to)13639-13645
Number of pages7
JournalACS Sustainable Chemistry and Engineering
Volume7
Issue number16
DOIs
Publication statusPublished - 19 Aug 2019

Keywords

  • Homogeneous catalysis
  • Ionic liquids
  • Lewis acids
  • Metallocenes
  • Molybdenum
  • Rearrangement
  • Renewable resources
  • Terpenes

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