M. Matsuzono et al. / Tetrahedron Letters 42 (2001) 7621–7623
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3. (a) Amat, M.; Hadida, S.; Sathynarayan, S.; Bosch, J. J.
Org. Chem. 1994, 59, 10; (b) Amat, M.; Hadida, S.;
Sathynarayan, S.; Bosch, J. Org. Synth. 1996, 74, 248; (c)
Amat, M.; Sathynarayan, S.; Hadida, S.; Bosch, J. Hete-
rocycles 1996, 43, 1713.
4. Directed C-3 lithiation promoted by a directing group at
the 2-position has been reported. (a) Johnson, D. A.;
Gribble, G. W. Heterocycles 1986, 244, 2127; (b) Gribble,
G. W.; Johnson, D. A. Tetrahedron Lett. 1987, 44, 5259;
(c) Comins, D. L.; Killpack, M. O. J. Org. Chem. 1987,
52, 104; (d) Yokoyama, Y.; Uchida, M.; Murakami, Y.
Heterocycles 1989, 29, 1661; (e) Grimaldi, T.; Romero,
M.; Pujol, M. D. Synlett 2000, 1788.
5. For C-2 lithiation of N-protected indoles, see: Rewcastle,
G. W.; Katritzky, A. R. Adv. Heterocycl. Chem. 1993, 56,
172–178.
6. Klingebiel, U.; Lu¨ttke, W.; Noltemeyer, M.; Schmidt, H.
G. J. Organomet. Chem. 1993, 456, 41.
7. (a) Fukuda, T.; Maeda, R.; Iwao, M. Tetrahedron 1999,
55, 9151; (b) Fukuda, T.; Mine, Y.; Iwao, M. Tetra-
hedron 2001, 57, 975.
8. Beswick, P. J.; Greenwood, C. S.; Mowlem, T. J.; Nech-
vatal, G.; Widdowson, D. A. Tetrahedron 1988, 44, 7325.
9. 1H NMR spectrum of 1 (CDCl3, 400 MHz): l 1.14 (d,
J=7.7 Hz, 18H), 1.70 (sept, J=7.7 Hz, 3H), 6.62 (dd,
J=1.1 and 3.3 Hz, 1H), 7.10 (dt, J=1.5 and 7.3 Hz, 1H),
7.13 (dt, J=1.5 and 7.3 Hz, 1H), 7.37 (d, J=3.3 Hz, 1H),
7.51 (d, J=7.3 Hz, 1H), 7.62 (d, J=7.3 Hz, 1H). Deu-
terium incorporation at C-3 was estimated by integration
of an absorption of H-3 using that of H-7 as the refer-
ence. The signals at l 6.62 and l 7.51 were assigned to be
H-3 and H-7 protons, respectively by the NOE experi-
ments.
10. For the similar rearrangements, see: (a) Sundberg, R. J.;
Russek, H. F. J. Org. Chem. 1973, 38, 3324; (b) Bray, B.
L.; Mathies, P. H.; Naef, R.; Solas, D. R.; Tidwell, T. T.;
Atris, D. R.; Muchowski, J. M. J. Org. Chem. 1990, 55,
6317; (c) Iwao, M. Heterocycles 1993, 36, 29.
11. sec-BuLi-tert-BuOK has been used for the C-2-selective
lithiation of 1-(2,2-diethylbutanoyl)indole, see: Ref. 7b.
12. Stannety, P.; Mihovilovic, M. D. J. Org. Chem. 1997, 62,
1514.
13. Iwao, M.; Motoi, O. Tetrahedron Lett. 1995, 36, 5929.
14. Typical experimental procedure for the synthesis of 3-sub-
stituted 1-(triisopropylsilyl)indoles 4. Under an argon
atmosphere, tert-BuLi (1.42 M in pentane, 1.06 mL, 1.5
mmol) was added dropwise to a stirred solution of 1
(273.5 mg, 1.0 mmol) and TMEDA (272 mL, 1.8 mmol)
in dry hexane (5 mL) at 0°C and the mixture was stirred
for 3 h at the same temperature. After cooling to −78°C,
a solution of the electrophile (3.0 mmol) in dry diethyl
ether (5 mL) was added. (In the reactions with MeI and
TMSCl, the electrophiles were added at 0°C.) The mix-
ture was stirred for 1 h at −78°C and then allowed to
warm to 0°C and quenched with saturated aqueous
NH4Cl. After usual extractive workup, the crude product
was purified by column chromatography [Silica Gel
FL100D (Fuji Silysia)] using a mixture of hexane–ethyl
acetate (50:1–5:1) as eluent. Compound 4b was purified
over Silica Gel Chromatorex NH-DM1020 (Fuji Silysia)
using hexane as eluent.