K. Fujita et al. / Tetrahedron Letters 45 (2004) 3215–3217
3217
6. (a) Fujita, K.; Furukawa, S.; Yamaguchi, R. J. Organo-
met. Chem. 2002, 649, 289; (b) Fujita, K.; Yamamoto, K.;
Yamaguchi, R. Org. Lett. 2002, 4, 2691; (c) Fujita, K.; Li,
Z.; Ozeki, N.; Yamaguchi, R. Tetrahedron Lett. 2003, 44,
2687.
Acknowledgements
This work was supported in part by Grant-in-Aid for
Scientific Research from Japan Society for the Promo-
tion of Science (No. 14550806).
7. Several groups have reported hydrogen transfer reactions
catalyzed by CpꢀIr complexes: (a) Mashima, K.; Abe, T.;
Tani, K. Chem. Lett. 1998, 1199; (b) Murata, K.; Ikariya,
T.; Noyori, R. J. Org. Chem. 1999, 64, 2186; (c) Ogo, S.;
Makihara, N.; Watanabe, Y. Organometallics 1999, 18,
5470; (d) Ogo, S.; Makihara, N.; Kaneko, Y.; Watanabe,
Y. Organometallics 2001, 20, 4903; (e) Suzuki, T.; Morita,
K.; Tsuchida, M.; Hiroi, K. Org. Lett. 2002, 4, 2361; (f)
Suzuki, T.; Morita, K.; Tsuchida, M.; Hiroi, K. J. Org.
Chem. 2003, 68, 1601; (g) Abura, T.; Ogo, S.; Watanabe,
Y.; Fukuzumi, S. J. Am. Chem. Soc. 2003, 125, 4149.
8. Typical procedure: In a 50 mL glass reactor under an
atmosphere of argon were placed [CpꢀIrCl2]2 in 2-propa-
nol (9.5 mL) and H2O (0.5 mL). Then quinolines
(2.0 mmol) and 60% HClO4 aq (10 mol %) were added,
and the mixture was stirred under reflux for 17 h. GC
yields were obtained by using undecane as an internal
standard (Shimadzu GC-14A gas chromatograph with
capillary column CBP1-M25-025). The products were
isolated by silica gel column chromatography. The prod-
ucts were identified by NMR analysis.
9. [CpꢀIrHCl]2 also showed catalytic activity to give 1,2,3,4-
tetrahydroquinoline in 34% yield, while other catalysts
such as [CpꢀIrCl(PPh3)2]CF3SO3, [IrCl(cyclooctene)2]2 or
IrCl3Æ5H2O did not show any activity.
10. N-Isopropyl-1,2,3,4-tetrahydroquinoline would be formed
via N-alkylation of 1,2,3,4-tetrahydroquinoline. CpꢀIr-
catalyzed N-alkylation of amines with alcohols has been
reported by us.6c
11. Reaction of 4-methylquinoline was sluggish; the yield was
39% even with higher catalyst loading and longer reaction
time (Table 2, entry 5). Addition of HClO4 was not
effective for this reaction.
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