872
M. Ahmed et al. / Tetrahedron Letters 45 (2004) 869–873
Table 3. One pot synthesis of indoles from olefinsa
Entry
1
Olefin
Hydrazine
Indol
Yieldb
85
n:iso
H
N
99:1
H2N
N
H
H
O
O
N
2
3
4
5
6
80
80
75
80
85
99:1
99:1
77:23
99:1
99:1
H2N
N
H
H
N
H2N
N
H
N
H2N
N
N
Ph
N
H2N
H
N
Cl
H2N
N
Cl
H
a Reaction conditions: olefin (10 mmol), hydrazine (10 mmol), Rh(CO)2acac (0.1 mol %), Iphos (0.2 mol %), toluene (30 mL), CO/H2 (1:1, 10 bar),
temperature (65 °C), time (16 h), then 4 equiv of ZnCl2 are added, and reaction is heated until conversion is complete.
b Isolated yield based on hydrazine.
Neibecker, D. In Catalytic Heterofunctionalization; Togni,
advantageous and environmentally friendly because
waste generation during work-up steps is minimized. In
addition, time and energy is saved.
€
A., Grutzmacher, H., Eds.; Wiley-VCH: Weinheim, 2001.
2. Eilbracht, P.; Barfacker, L.; Buss, C.; Hollmann, C.;
€
Kitsos-Rzychon, B. E.; Kranemann, C. L.; Rische, T.;
Roggenbuck, R.; Schmidt, A. Chem. Rev. 1999, 99, 3329–
3365.
€ €
3. Selected examples: (a) Toros, S.; Gemes-Pesci, I.; Heil, B.;
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€
We thank Prof. Peter Eilbracht (Universitat Dortmund)
for general discussions and information about his
work on indole syntheses from olefins. S. Buchholz,
H. Baudisch, K. Reincke, Dr. C. Fischer, Prof. M.
Michalik and Dr. W. Baumann (all IfOK) are thanked
for excellent analytical support. This work has been
financed by the State of Mecklenburg–Western Pom-
€
4. (a) Rische, T.; Barfacker, L.; Eilbracht, P. Eur. J. Org.
Chem. 1999, 3, 653–660; (b) Rische, T.; Kitsos-Rzychon,
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merania and the Bundesministerium fur Bildung und
Forschung (BMBF).
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9. General procedure: All carbonylation experiments were
carried out in a Parr stainless steel autoclave (100 mL). In