Molecular sieves 4A work to mediate the catalytic metal enolization of nucleophile precursors: application to catalyzed enantioselective Michael addition reactions

Tetrahedron Letters

Volumn 49, Issue 35, 2008, Pages 5220-5223

  Hasegawa, Masayuki ^b   Ono, Fumiyasu ^b   Kanemasa, Shuji ^a  

^a Institute for Materials Chemistry and Engineering   (Japan)

^b KYUSHU UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

ALPHA,BETA UNSATURATED CARBONYL DERIVATIVE; CARBONYL DERIVATIVE; HYDROGEN; LEWIS ACID; NICKEL; NICKEL ACETATE; NICKEL COMPLEX; NICKEL ENOLATE; NITROMETHANE;

ARTICLE; CATALYSIS; CHEMICAL REACTION; CHEMICAL STRUCTURE; CHIRALITY; ENANTIOSELECTIVITY; MICHAEL ADDITION;

EID: 47049085927     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tetlet.2008.05.156     Document Type: Article

References (18)

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6. Ono, F.; Hasegawa, M.; Tanaka, J.; Kanemasa, S. Tetrahedron Lett., 2008, 49, accepted for publication.
7. a Values measured in DMSO of the following nucleophile precursors: dimedone: 11.16. Arnett E.M., and Harrelson Jr. J.A. J. Am. Chem. Soc. 109 (1987) 809-812
8. malononitrile: 11.1 and nitromethane: 17.2. Matthews W.S., Bares J.E., Bartmess J.E., Bordwell F.G., Cornforth F.J., Drucker G.E., Margolin Z., McCallum R.J., McCollum G.J., and Vanier N.R. J. Am. Chem. Soc. 97 (1975) 7006-7014
9. MS3A was similarly effective as well.
10. Commercially available MS4A powder was used without further preactivation procedure in the present reactions.
11. A strong Lewis acid catalyst should be kinetically favored for the catalytic generation of metal enolates as the forward transformation, but the ready proton quenching with the resulting strong acid is even more favored thermodynamically. If MS4A works as effective proton scavenger, the combined use of a strong Lewis acid and MS4A should result in the effective generation of metal enolates in high concentration.
12. For the generation and reactions of nickel(II) enolate, see:. Campora J., Maya C.M., Palma P., Carmona E., Gutierrez-Puebla E., and Ruiz C. J. Am. Chem. Soc. 125 (2003) 1482-1483
13. Mahandru G.M., Skauge A.R., Chowdhury S.K., Amarasinghe K.K.D., Heeg M.J., and Montgomery J. J. Am. Chem. Soc. 125 (2003) 13481-13485
14. Previous reports presenting the reaction examples in which MS4A worked as effective base in synthetic organic reactions:. Weinstock L.M., Karady S., Roberts F.E., Hoinowski A.M., Brenner G.S., Lee T.B.K., Lumma W.C., and Sletzinger M. Tetrahedron Lett. 16 (1975) 3979-3982
15. Terada M. Synth. Org. Chem. Jpn. 65 (2007) 748-759
16. It has remained unclear so far that the combined use of a strong Lewis acid catalyst and MS4A led to a low enantioselectivity in the Michael addition reactions.
17. Ion exchange of MS4A is well known in water:. Sherman J.D. Appl. Sci. 80 (1984) 583-623
18. Townsend R.P., and Harjula R. Mol. Sieves 3 (2002) 1-42