Ru(iv)-catalyzed isomerization of allylamines in water: A highly efficient procedure for the deprotection of N-allylic amines

Chemical Communications

Volumn , Issue 32, 2005, Pages 4086-4088

  Cadierno, Victorio ^a   García Garrido, Sergio E ^a   Gimeno, José ^a   Nebra, Noel ^a  

^a UNIVERSITY OF OVIEDO   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

ALLYL COMPOUND; ALLYLAMINE; RUTHENIUM COMPLEX; WATER;

ANALYTIC METHOD; AQUEOUS SOLUTION; ARTICLE; CATALYSIS; COMPLEX FORMATION; DEPROTECTION REACTION; ISOMERIZATION;

EID: 23944483168     PISSN: 13597345     EISSN: None     Source Type: Journal    
DOI: 10.1039/b506788j     Document Type: Article

References (25)

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8. See for example: F. Guibé, Tetrahedron, 1998, 54, 2967 and references therein.
9. The use of nickel catalysts, which also require the presence of a nucleophilic scavenger, has been reported: T. Taniguchi and K. Ogasawara, Tetrahedron Lett, 1998, 39, 4679.
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11. (b) B. Alcaide, P. Almendros and J. M. Alonso, Chem Eur. J., 2003, 9, 5793.
12. Formation of an active hydride intermediate by decomposition of the Grubbs' carbenes has been proposed but no experimental evidence has been provided (see ref. 5b). Nevertheless, it should be noted that isomerization of N-allylic substrates to give the corresponding enamines catalyzed by Ru-hydride complexes has been extensively studied in organic media: S. Krompiec, M. Pigulla, N. Kuźnik, M. Krompiec, B. Marciniec, D. Chadyniak and J. Kasperczyk, J. Mol. Catal. A: Chem., 2005, 225, 91 and references therein.
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15. 2O with butadiene and isoprene, respectively. See: (a) J. K. Nicholson and B. L. Shaw, J. Chem. Soc. A, 1966, 807;
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17. Complexes 1 and 2 are efficient catalysts for the isomerization of allylic alcohols into carbonyl compounds in both organic and aqueous media. See: V. Cadierno, S. E. García-Garrido and J. Gimeno, Chem. Commun., 2004, 232.
18. B. Alcaide, P. Almendros, J. M. Alonso and A. Luna, Synthesis, 2005, 668.
19. Yields up to 95% were obtained, after 26 h at 90 °C, using a catalyst loading of 2 mol% of Ru. Yields up to 81% were obtained, after 24 h at 70 °C, using a catalyst loading of 3 mol% of Ru.
20. 12 Close examination revealed that the reaction mixtures are in most of the cases emulsions rather than homogeneous solutions.
21. The presence of a benzyl substituent seems to promote slower transformations (entries 13 and 18). A clear example of this situation is the deprotection of (S)N-allyl-N-benzyl-α-methylbenzylamine catalyzed by complex 1 in which only 81% of conversion was attained after 22 h (entry 18). At present, no explanation for this particular behaviour can be provided.
22. Confirmed by GC, using a Supelco Beta-Dex™ 120 (30 m, 250 μm) chiral column, by comparison with a commercially available pure sample of (S)-N-benzyl-α-methylbenzylamine.
23. (a) C. J. Li and T. H. Chan, Organic Reactions in Aqueous Media, John Wiley & Sons, New York, 1997;
24. U. M. Lindström, Chem. Rev., 2002, 102, 2751 and references therein;
25. (b) For a recent review on ruthenium-catalyzed reactions in aqueous media see: M. Wang and C. J. Li, in Ruthenium Catalysts and Fine Chemistry, ed. C. Bruneau and P. H. Dixneuf, Springer-Verlag, Berlin, 2004.