Journal of Chemical Sciences

, Volume 116, Issue 3, pp 159–162 | Cite as

Proline-catalysed asymmetric ketol cyclizations: The template mechanism revisited

  • R. Malathi
  • D. Rajagopal
  • Zoltan G. Hajos
  • S. Swaminathan


A modified template mechanism based on modelling studies of energy minimised complexes is presented for the asymmetric proline-catalysed cyclization of triketones1,2 and3 to the 2S,3S-ketols1a,2a and3a respectively. The template model involves a three-point contact as favoured in enzyme-substrate interactions. Our minimisation studies are in agreement with the divergent behaviour of the 6,5-, 6,6-and 6,7-bicyclic systems. They support the high 93.4%ee observed with the 6,5-bicyclic ketol and the lower 73%ee found with the 6,6-bicyclic ketol. The calculations also explain the lack of asymmetric induction with the 6,7-bicyclic system


Proline-catalysed ketol cyclization template mechanism 


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Copyright information

© Indian Academy of Sciences 2004

Authors and Affiliations

  • R. Malathi
    • 1
  • D. Rajagopal
    • 2
  • Zoltan G. Hajos
    • 3
  • S. Swaminathan
    • 2
  1. 1.Department of Crystallography and BiophysicsUniversity of MadrasChennaiIndia
  2. 2.Department of Organic ChemistryUniversity of MadrasChennaiIndia
  3. 3.Hoffmann-La Roche IncNutleyUSA

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