Iridium-catalyzed asymmetric hydrogenation of N-protected indoles

Chemistry - A European Journal

Volumn 16, Issue 7, 2010, Pages 2036-2039

  Baeza, Alejandro ^a   Pfaltz, Andreas ^a  

^a UNIVERSITY OF BASEL   (Switzerland)

Author keywords

Asymmetric catalysis; Hydrogenation; Indoles; Indolines; Iridium

Indexed keywords

ASYMMETRIC CATALYSIS; ASYMMETRIC HYDROGENATION; CHEMICAL EQUATIONS; ELEVATED TEMPERATURE; ENANTIOMERIC EXCESS; HIGH YIELD; N ,P LIGANDS; REACTIVE SUBSTRATES;

CATALYSIS; ENANTIOSELECTIVITY; IRIDIUM;

HYDROGENATION;

INDOLE DERIVATIVE; IRIDIUM;

ARTICLE; CATALYSIS; CHEMICAL STRUCTURE; CHEMISTRY; HYDROGENATION; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY;

CATALYSIS; HYDROGENATION; INDOLES; IRIDIUM; MAGNETIC RESONANCE SPECTROSCOPY; MOLECULAR STRUCTURE;

EID: 76449110295     PISSN: 09476539     EISSN: 15213765     Source Type: Journal    
DOI: 10.1002/chem.200903105     Document Type: Article

References (34)

1. For example, see: a) I. W. Southon, J. Buckingham in Dictionary of Alkaloids, Chapman and Hall, New York, 1989;
2. b) N. Neuss, M. N.Neuss in The Alkaloids (Eds.: A. Brossi, M. Suffness), Academic Press, San Diego, 1990, p. 229;
3. c) F. Gueritte, J. Fahy in Anticancer Agents from Natural Products (Eds.: G. M. Cragg, D. G. I. Kingstom, D. J. Newman), CRC Press, Boca Raton, 2005, p. 123;
4. d) Modern Alkaloids (Eds.: E. Fattorusso, O. Taglialatela-Scafati), Wiley-VCH, Weinheim, 2008, and references therein.
5. Selected examples: a) R. K. Kunz, D. W. C. MacMillan, J. Am. Chem. Soc. 2005, 127, 3240-3241;
6. b) F. Andersson, E. Hedenström, Tetrahedron: Asymmetry 2006, 17, 1952-1957;
7. c) A. Hartikka, P.I. Arvidsson, J. Org. Chem. 2007, 72, 5874-5877, and references therein.
8. Selected examples: a) B. Orsat, P. B. Alper, W. Moree, C.-P. Mak, C.-H. Wong, J. Am. Chem. Soc. 1996, 118, 712-713;
9. b) V. GotorFernández, P. Fernández-Torres, V. Gotor, Tetrahedron: Asymmetry 2006, 17, 2558-2564;
10. c) F. O. Arp, G. C Fu, J. Am. Chem. Soc. 2006, 128, 14264-14265;
11. d) X. L. Hou, B. H. Zheng, Org. Lett. 2009, 11, 1789-1791;
12. e) S. Anas, H. B. Kagan, Tetrahedron: Asymmetry 2009, 20, 2193-2199, and references therein.
13. f) Y.-G. Zhou, Acc. Chem. Res. 2007, 40, 1357-1366, and references therein.
14. a) R. Kuwano, K. Sato, T. Kurokawa, D. Karube, Y Ito, J. Am. Chem. Soc. 2000, 122, 7614-7615;
15. b) R. Kuwano, K. Kaneda, T. Ito, K. Sato, T. Kurokawa, Y. Ito, Org. Lett. 2004, 6, 2213-2215;
16. c) R. Kuwano, M. Kashiwabara, Org. Lett. 2006, 8, 2653-2655;
17. d) R. Kuwano, M. Kashiwabara, K. Sato, T. Ito, K. Kaneda, Y. Ito, Tetrahedron: Asymmetry 2006, 17, 521-535. The same catalytic system has recently been applied to the asymmetric hydrogenation of NBoc-substituted pyrroles:
18. e) R. Kuwano, M. Kashiwabara, M. Ohsumi, H. Kusano, J. Am. Chem. Soc. 2008, 130, 808-809.
19. Reviews: a) S. Roseblade, A. Pfaltz, Acc. Chem. Res. 2007, 40, 1402-1411;
20. b)K. Källström, I. Munslow, P. G. Andersson, Chem. Eur. J. 2006, 12, 3194-3200;
21. c) X. Cui, K. Burgess, Chem. Rev. 2005, 105 3272-3296.
22. See the Supporting Information for details.
23. For the use of these catalysts for the asymmetric hydrogenation of tetrasubstituted olefins, see: M. G. Schrems, E. Neumann, A. Pfaltz, Angew. Chem. 2007, 119, 8422-8424;
24. Angew. Chem. Int. Ed. 2007, 46, 8274-8276.
25. a) S. Kaiser, S. P. Smidt, A. Pfaltz, Angew. Chem. 2006, 118, 5318-5321;
26. Angew. Chem. Int. Ed. 2006, 45, 5194-5197.
27. For other application of these catalysts, see: b) S. Bell, B. Wüstenberg, S. Kaiser, F. Menges, T. Netscher, A. Pfaltz, Science 2006, 311, 642-644;
28. c) A. Wang, B. Wüstenberg, A. Pfaltz, Angew. Chem. 2008, 120, 2330-2332;
29. Angew. Chem. Int. Ed. 2008, 47, 2298-2300;
30. d) A. Baeza, A. Pfaltz, Chem. Eur. J. 2009, 15, 2266-2269.
31. When these conditions were applied to substrate 1c, partial deprotection was observed. The lower ee of the deprotected product indicates that cleavage of the N-Boc group occurs (at least in part) before hydrognation, because unprotected indoles were found to react with lower enantioselectivity than N-protected derivatives.
32. a) F. Menges, A. Pfaltz, Adv. Synth. Catal. 2002, 344, 40-44;
33. b) S. McIntyre, E. Hörmann, F. Menges, S. P. Smidt, A. Pfaltz, Adv. Synth. Catal. 2005, 347, 282-288;
34. c) A. Baeza, A. Pfaltz, Synlett 2008, 3167-3171.