Enantioselective conjugate radical addition to β-acyloxy acrylate acceptors: An approach to acetate aldol-type products

Angewandte Chemie - International Edition

Volumn 42, Issue 37, 2003, Pages 4521-4523

  Sibi, Mukund P ^a   Zimmerman, Jake ^a   Rheault, Tara ^a  

^a NORTH DAKOTA STATE UNIVERSITY   (United States)

Author keywords

Acrylates; Asymmetric catalysis; Enantioselectivity; Lewis acids; Radical reactions

Indexed keywords

ADDITION REACTIONS; CHEMICAL BONDS; FREE RADICALS; REACTION KINETICS; STEREOCHEMISTRY;

CONFORMERS;

ACRYLIC MONOMERS;

ACETIC ACID DERIVATIVE; ACRYLIC ACID DERIVATIVE;

ALDOL REACTION; ANALYTIC METHOD; ARTICLE; CHEMICAL BINDING; CHIRALITY; CONJUGATION; ENANTIOSELECTIVITY; ION TRANSPORT; MOLECULAR STABILITY; REACTION ANALYSIS; STRUCTURE ANALYSIS;

ACETATES; ACRYLATES; ALDEHYDES; FREE RADICALS; MOLECULAR STRUCTURE; OXIDATION-REDUCTION; STEREOISOMERISM;

EID: 0141558931     PISSN: 14337851     EISSN: None     Source Type: Journal    
DOI: 10.1002/anie.200352096     Document Type: Article

References (36)

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28. For general information and reaction details for Lewis acid mediated conjugate radical addition, see M. P. Sibi, J. Ji, J. B. Sausker, C. P. Jasperse, J. Am. Chem. Soc. 1999, 121, 7517 see also P. Renaud, M. Gerster, Angew. Chem. 1998, 110, 2704; Angew. Chem. Int. Ed. 1998, 37, 2562.
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30. In addition to ligand 6, we have evaluated bisoxazolines derived from amino indanol and phenyl glycinol and found them to be less efficient with respect to selectivity. Of the four magnesium Lewis acids tested (bromide, iodide, perchlorate, and triflimide), the iodide gave the best results in combination with 6.
31. The aldol product containing donor atoms may not readily dissociate from the chiral Lewis acid and thus compete for coordination with the substrate. This explanation is consistent with the need for stoichiometric amounts of the chiral Lewis acid to obtain high ee values. REACT IR studies provide additional support for our explanation. These results will be reported later.
32. In reactions where radical addition is inefficient, triethylborane can participate and provide minor amounts of a product derived from ethyl radical addition.
33. See Supporting Information.
34. For a discussion on the geometry of the reactive complex, see a) M. P. Sibi, J. Ji, J. H. Wu, S. Gürtler, N. A. Porter, J. Am. Chem. Soc. 1996, 118, 9200; M. P. Sibi, J. Ji, J. Org. Chem. 1997, 62, 3800; M. P. Sibi, M. Liu, Curr. Org. Chem. 2001, 5, 719.
35. For a discussion on the geometry of the reactive complex, see a) M. P. Sibi, J. Ji, J. H. Wu, S. Gürtler, N. A. Porter, J. Am. Chem. Soc. 1996, 118, 9200; M. P. Sibi, J. Ji, J. Org. Chem. 1997, 62, 3800; M. P. Sibi, M. Liu, Curr. Org. Chem. 2001, 5, 719.
36. For a discussion on the geometry of the reactive complex, see a) M. P. Sibi, J. Ji, J. H. Wu, S. Gürtler, N. A. Porter, J. Am. Chem. Soc. 1996, 118, 9200; M. P. Sibi, J. Ji, J. Org. Chem. 1997, 62, 3800; M. P. Sibi, M. Liu, Curr. Org. Chem. 2001, 5, 719.