Poly(ethylene glycol)-Supported Chiral Imidazolidin-4-one: An Efficient Organic Catalyst for the Enantioselective Diels-Alder Cycloaddition

Advanced Synthesis and Catalysis

Volumn 344, Issue 2, 2002, Pages 149-152

  Benaglia, Maurizio ^a   Celentano, Giuseppe ^a   Cinquini, Mauro ^a   Puglisi, Alessandra ^a   Cozzi, Franco ^a  

^a UNIVERSITY OF MILAN   (Italy)

Author keywords

Asymmetric catalysis; Catalyst immobilization; Chiral organic catalysts; Diels Alder cycloadditions; Soluble polymers

Indexed keywords

EID: 0000779935     PISSN: 16154150     EISSN: None     Source Type: Journal    
DOI: 10.1002/1615-4169(200202)344:2<149::AID-ADSC149>3.0.CO;2-U     Document Type: Article

References (21)

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3. For recent reports comparing the efficiency of soluble and insoluble polymer-supported catalysts see: a) T. S. Reger, K. D. Janda, J. Am. Chem. Soc. 2000, 122, 6929-6934; b) R. Annunziata, M. Benaglia, M. Cinquini, F. Cozzi, G. Tocco, Org. Lett. 2000, 2, 1737-1739.
4. For recent reports comparing the efficiency of soluble and insoluble polymer-supported catalysts see: a) T. S. Reger, K. D. Janda, J. Am. Chem. Soc. 2000, 122, 6929-6934; b) R. Annunziata, M. Benaglia, M. Cinquini, F. Cozzi, G. Tocco, Org. Lett. 2000, 2, 1737-1739.
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9. Review on asymmetric organic catalysis: P. I. Dalko, L. Moisan Angew. Chem. Int. Ed. Engl. 2001, 40, 3726-3748.
10. [4d]) and insoluble, polystyrene-supported bisoxazolines/Cu(II) complexes - see: S. Orlandi, A. Mandoli, D. Pini, P. Salvadori, Angew. Chem. Int. Ed. Engl. 2001, 40, 2519-2521 - showed considerable decrease of catalytic efficiency upon recovery and recycling. In both cases addition of metal was necessary to fully restore the catalytic activity of the immobilized species.
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13. for other applications of ammonium salts derived from imidazolidin-4-ones as chiral organic catalysts see: b) W. S. Jen, J. J. M. Wiener, D. W. C. MacMillan, J. Am. Chem. Soc. 2000, 122, 9874-9875; c) N. A. Paras, D. W. C. MacMillan, J. Am. Chem. Soc. 2001, 123, 4370-4371.
14. for other applications of ammonium salts derived from imidazolidin-4-ones as chiral organic catalysts see: b) W. S. Jen, J. J. M. Wiener, D. W. C. MacMillan, J. Am. Chem. Soc. 2000, 122, 9874-9875; c) N. A. Paras, D. W. C. MacMillan, J. Am. Chem. Soc. 2001, 123, 4370-4371.
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19. The GC yields (cycle, at 24 h, at 40 h, isolated) were the following: 1, 64%, 77.5%, 67%; 2, 60%, 73%, 60%; 3, 26%, 51%, 48%; 4, undetermined, 35%, 33%. The GC analysis did not show the presence of any degradation products. Endo/exo ratios were identical to those reported in entries 8, 13 - 15. In the reactions carried out with recycled catalysts the amounts of reagents and solvents for a new cycle were adjusted to the amount of recovered 3.
20. 2000.
21. 1H NMR spectrum of endo-4 lists 13 rather than 12 protons.