No.105
Synthesis of 3-Substituted Indoles
| B2057 | 3-Bromo-1-(triisopropylsilyl)indole (1) |
1g |
The 3-lithiated indole is generated from silylindole 1 by treatment with alkyllithium and when allowed to react at -78°C with various electrophiles, regioselectively yields 3-substituted indoles in good yield . This is because the lithiated intermediate contains a bulky triisopropylsilyl group at the 1-position. The steric bulk provides protection at the 2-position of indole which prevent 3→2 migration of lithium and subsequent ring fragmentation1).
Reported applications of 1 are the synthesis of tryptophan2) and the total synthesis of grossularine-13) which is a type of alkaloid.
References
1) Synthesis of 3-substituted indoles
M. Amat, S. Sathyanarayana, S. Hadida, J. Bosch, Heterocycles, 43, 1713 (1996).
2) Synthesis of β-Methyltryptophan
R. S. Hoerrner, D. Askin, R. P. Volante, P. J. Reider, Tetrahedron Lett., 39, 3455 (1998).
3) Total synthesis of Grossularines-1 and -2
T. Choshi, S. Yamada, E. Sugino, T. Kuwada, S. Hibino, J. Org. Chem., 60, 5899 (1995).
M. Amat, S. Sathyanarayana, S. Hadida, J. Bosch, Heterocycles, 43, 1713 (1996).
2) Synthesis of β-Methyltryptophan
R. S. Hoerrner, D. Askin, R. P. Volante, P. J. Reider, Tetrahedron Lett., 39, 3455 (1998).
3) Total synthesis of Grossularines-1 and -2
T. Choshi, S. Yamada, E. Sugino, T. Kuwada, S. Hibino, J. Org. Chem., 60, 5899 (1995).
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