Communications
Table 3: Synthesis of 3-alkyl-N-hydroxyindolesthrough 1,5-addition of silyl enol ethers 24 and 25 to substituted a,b-unsaturated nitrones IV.[a,b]
Entry
a,b-Unsaturated
nitro ketoester
Product V
Yield
[%][c]
Product VI
Yield
[%][c]
1
61
73
2
3
4
5
44
45
57
43
61
61
46
40
[a] Reactionswere carried out on a scale of 0.06–0.10 mmol in anhydrousDME (concentration: 0.12–0.16 m), and the productswere purified by
preparative TLC (silica gel). [b] In each case, a minor by-product corresponding to compound 4 was formed (see Table 1 and Table 2), but not isolated.
[c] Yield of isolated product.
[3] For selected reviews on N-hydroxyindoles and their derivatives,
see: a) M. Somei, Adv. Heterocycl. Chem. 2002, 82, 101 – 155;
b) M. Somei, Heterocycles 1999, 50, 1157 – 1211; c) R. M. Ache-
son, Adv. Heterocycl. Chem. 1990, 51, 105 – 175.
molecular complexity and diversity for biological and phar-
maceutical purposes in particular.
Received: May 8, 2006
[4] a) M. Belley, E. Sauer, D. Beaudoin, P. Duspara, L. Trimble, P.
DubØ, Tetrahedron Lett. 2006, 47, 159 – 162; b) A. Penoni, G.
Palmisano, G. Broggini, A. Kadowaki, K. M. Nicholas, J. Org.
Chem. 2006, 71, 823 – 825; c) A. Wong, J. T. Kuethe, I. W. Davies,
J. Org. Chem. 2003, 68, 9865 – 9866; d) A. G. Myers, S. B. Herzon,
J. Am. Chem. Soc. 2003, 125, 12080 – 12081; e) S. Katayama, N.
Ae, R. Nagata, J. Org. Chem. 2001, 66, 3474 – 3483; f) Z. Wróbel,
M. Ma¸kosza, Tetrahedron 1997, 53, 5501 – 5514; g) A. Reissert, H.
Heller, Ber. Dtsch. Chem. Ges. 1904, 37, 4364 – 4379.
[5] This type of reaction is sometimes referred to as a 1,4-addition.
[6] For a comprehensive review on nitrones, see: P. Merino, Science
of Synthesis, Vol. 27 (Ed.: A. Padwa), Thieme, New York, 2004,
pp. 511 – 580.
[7] CCDC 603155 (19) and 603156 (23) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
[8] a) G. K. S. Prakash, J. Hu, G. A. Olah, J. Fluorine Chem. 2001,
112, 357 – 362; b) H. Amii, T. Kobayashi, Y. Hatamoto, K.
Uneyama, Chem. Commun. 1999, 1323 – 1324.
Published online: July 18, 2006
Keywords: N-hydroxyindoles· nitrogen heterocycles· silanes·
.
stannanes · synthetic methods
[1] K. C. Nicolaou, S. H. Lee, A. A. Estrada, M. Zak, Angew. Chem.
2005, 117, 3802–3806; Angew. Chem. Int. Ed. 2005, 44, 3736–3740.
[2] a) W. Li, J. E. Leet, H. A. Ax, D. R. Gustavson, D. M. Brown, L.
Turner, K. Brown, J. Clark, H. Yang, J. Fung-Tomc, K. S. Lam, J.
Antibiot. 2003, 56, 226 – 231; b) J. E. Leet, W. Li, H. A. Ax, J. A.
Matson, S. Huang, R. Huang, J. L. Cantone, D. Drexler, R. A.
Dalterio, K. S. Lam, J. Antibiot. 2003, 56, 232 – 242; c) K. L.
Constantine, L. Mueller, S. Huang, S. Abid, K. S. Lam, W. Li, J. E.
Leet, J. Am. Chem. Soc. 2002, 124, 7284 – 7285; d) nocathiacin
antibiotics: J. E. Leet, H. A. Ax, D. R. Gustavson, D. M. Brown,
L. Turner, K. Brown, W. Li, K. S. Lam, WO 2000003722A1
[Chem. Abstr. 2000, 132, 121531]; e) T. Sasaki, T. Otani, H.
Matsumoto, N. Unemi, M. Hamada, T. Takeuchi, M. Hori, J.
Antibiot. 1998, 8, 715 – 721.
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