PTS Amphiphile for Metathesis and Cross-Coupling in Water

By: Josephine Nakhla, Aldrich ChemFiles 2009, 9.2, 23.

Aldrich ChemFiles 2009, 9.2, 23.

Recently introduced by Professor Bruce Lipshutz of UC-Santa Barbara, polyoxyethanyl α-tocopheryl sebacate (PTS) is a nonionic amphiphile that is proving to be a versatile “solubilizer” for organic molecules in water.1 Lipophilic substrates and catalysts can efficiently enter the micelles formed by PTS in water leading to important cross-coupling reactions at room temperature without the need for a co-solvent.


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Olefin Cross Metathesis2



Olefin Ring Closing Metathesis3



To use, one simply places the requisite amount of PTS (15 wt% in water) into a test tube with a stir bar and adds the organic substrate(s) and catalyst. Reactions are generally complete within 3–24 hours and can be accelerated if needed upon mild heating to 40–50 °C. Work-up is also very simple involving either extraction of the reaction mixture with EtOAc-hexane or deposition onto a bed of silica gel and elution with EtOAc. In most examples studied, PTS outperformed other non-ionic amphiphiles such as Triton®-X100 and Brij® 30.

Suzuki-Miyaura Coupling4



Heck Coupling5



Sonogashira Coupling6



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Materials

     

References

  1. Sold under license from Zymes, LLC.
  2. Lipshutz, B. H. et al. Org. Lett. 2008, 10, 1325.
  3. Lipshutz, B. H. et al. Adv. Synth. Catal. 2008, 350, 953.
  4. (a) Lipshutz, B. H. et al. Org. Lett. 2008, 10, 1333. (b) Lipshutz, B. H.; Abela, A. R. Org. Lett. 2008, 10, 5329.
  5. (a) Lipshutz, B. H.; Taft, B. R. Org. Lett. 2008, 10, 1329. (b) Neither acrylates nor styrenes any longer require 15 wt% PTS/ water in coupling to aryl iodides; see Lipshutz, B. H.; Ghorai, S. Aldrichimica Acta, 2008, 41, 59.
  6. Lipshutz, B. H. et al. Org. Lett. 2008, 10, 3793.

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