TADDOLs

Aldrich ChemFiles 2006, 6.4, 11.

Aldrich ChemFiles 2006, 6.4, 11.

Chiral Brønsted acid catalysts have recently become an important alternative to metal catalysts.1 Similar to several enzymatic processes, these reactions proceed through hydrogen-bonding activation.

Apart from numerous examples using TADDOLs in metal-catalyzed asymmetric reactions,2 Rawal recently reported that TADDOLs could be used as Brønsted acid organocatalysts in highly stereoselective hetero-Diels–Alder reactions.3 The reaction of an electron-rich diene with benzaldehyde using 10 mol % TADDOL (395242) provides the dihydropyrone as a single stereoisomer (Scheme 14).


 

Scheme 14.

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Materials

     

References

  1. (a) Schreiner, P. R. Chem. Soc. Rev. 2003, 32, 289. (b) Pihko, P. M. Angew. Chem. Int. Ed. 2004, 43, 2062.
  2. Seebach, D.; Beck, A. K.; Heckel, A. Angew. Chem. Int. Ed. 2001, 40, 92.
  3. Huang, Y.; Unni, A. K.; Thadani, A. N.; Rawal, V. H. Nature 2003, 424, 146.

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