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L. Pérez-Serrano et al.
SHORT PAPER
J = 8.2 Hz), 7.23 (t, 1 H, J = 7.7 Hz), 7.37 (d, 1 H, J = 8.2 Hz), 7.58
(d, 1 H, J = 7.7 Hz).
13C NMR (CDCl3): = 137.6, 136.9, 127.9, 125.4, 122.2, 120.7,
120.3, 117.0, 109.2, 100.2, 78.2, 72.5, 32.6.
mmol), butylamine (3.6 mL, 44.88 mmol), trimethylsilylacetylene
(3.2 mL, 22.44 mmol) and copper(I) iodide (0.43 g, 2.24 mmol) in
toluene (25 mL) was added and the mixture was stirred at r.t. for 4
h. The solvent was evaporated under vacuum and the crude was
purified by flash chromatography (hexane) to obtain 9.
Anal. Calcd for C13H11N: C, 86.15; H, 6.12; N, 7.73. Found: C,
86.30; H, 6.28; N, 7.85.
Yield: 1.82 g (85%); yellow solid; mp 92–93 °C (hexane–EtOAc).
IR (KBr): 3490, 3040, 2140 cm–1.
1-Allyl-1H-indole-2-carboxylic Acid Methyl Ester (5)
1H NMR (CDCl3): = 0.29 (s, 9 H), 6.79 (d, 1 H, J = 1.1 Hz), 7.13
(td, 1 H, J = 7.7, 1.1 Hz), 7.24 (td, 1 H, J = 8.2, 1.1 Hz), 7.31 (dd,
1 H, J = 8.2, 1.1 Hz), 7.59 (d, 1 H, J = 7.7 Hz), 8.18 (br s, 1 H).
13C NMR (CDCl3): = 135.8, 127.4, 123.6, 120.9, 120.4, 118.5,
110.7, 109.2, 98.4, 96.9, –0.19.
Following the same procedure used for the synthesis of 3, from 1H-
indole-2-carboxylic acid methyl ester (1.0 g, 5.71 mmol), aq NaOH
(30%; 65 mL), allyl bromide (0.74 mL, 8.56 mmol) and tetrabutyl
ammonium iodide (0.21 g, 0.57 mmol) and after purification by
flash chromatography (hexane–EtOAc, 9:1), 6 was obtained.
Yield: 1.1g (90%); colourless oil.
IR (neat): 3040, 2940, 1710, 1515 cm–1.
1H NMR (CDCl3): = 3.90 (s, 3 H), 4.88 (m, 1 H), 5.11 (m, 1 H),
5.24 (m, 2 H), 5.99 (m, 1 H), 7.20 (m, 2 H), 7.34 (m, 2 H), 7.69 (m,
1 H).
1-Allyl-2-ethynyl-1H-indole (10)
Following the same procedure used for the synthesis of 4, from 9
(0.5 g, 2.7 mmol), caesium carbonate (0.88 g, 2.70 mmol) and allyl
bromide (4.77 mL, 5.4 mmol) and after purification by flash chro-
matography (hexane), 10 was obtained.
Yield: 0.352 g (70%); pale yellow oil.
IR (neat): 3280, 3040, 2090 cm–1.
13C NMR (CDCl3): = 162.3, 139.1, 133.8, 126.9, 125.9, 125.1,
122.6, 120.7, 115.9, 110.7, 110.6, 51.6, 46.7.
1H NMR (CDCl3): = 3.46 (s, 1 H), 4.85–4.88 (m, 2 H), 4.97 (dd,
1 H, J = 17.0, 1.6 Hz), 5.15 (dd, 1 H, J = 9.9, 1.6 Hz), 5.90–6.02
(m, 1 H), 6.85 (s, 1 H), 7.09–7.15 (m, 1 H), 7.21–7.29 (m, 2 H), 7.59
(d, 1 H, J = 7.7 Hz).
13C NMR (CDCl3): = 136.4, 132.9, 126.9, 123.3, 121.1, 120.2,
116.6, 109.9, 108.7, 108.6, 83.4, 75.3, 46.4.
1-Allyl-1H-indole-2-carbaldehyde (6)1e
Following the same procedure employed for the synthesis of 1, from
5 (1.0 g, 4.65 mmol), DIBAL-H (1.5M in toluene; 7.75 mL, 11.63
mmol) and then by treatment of the crude product with manganese
oxide (3.97 g, 46.5 mmol) and purification by flash chromatography
(hexane–AcOEt, 9:1), 6 was obtained.
Anal. Calcd for C13H11N: C, 86.15; H, 6.12; N, 7.73. Found: C,
86.33; H, 6.26; N, 7.87.
Yield: 0.67 g (78%); colourless oil.
IR (neat): 2800, 1665, 1515 cm–1.
1H NMR (CDCl3): = 4.91 (dd, 1 H, J = 17.0, 1.1 Hz), 5.11 (dd, 1
H, J = 10.0, 1.1 Hz), 5.23 (m, 2 H), 5.93–6.05 (m, 1 H), 7.19 (td, 1
H, J = 8.2, 2.2 Hz), 7.30 (s, 1 H), 7.41 (m, 2 H), 7.75 (d, 1 H, J = 8.2
Hz), 9.89 (s, 1 H).
13C NMR (CDCl3): = 182.7, 140.3, 133.4, 133.3, 127.0, 123.4,
121.0, 118.1, 118.0, 116.3, 110.8, 46.7.
Acknowledgment
This work was supported by DGCYT (MEC-Spain, PB98-0053)
and the Universidad San Pablo-CEU (grant 02/01). L. P-S gratefully
acknowledges pre-doctoral fellowship from the Universidad San
Pablo-CEU.
1-Allyl-2-vinyl-1H-indole (7)
References
Following the same procedure used for the synthesis of 2, from me-
thyltriphenylphosphonium bromide (0.87 g, 2.43 mmol), KHMDS
(0.5M in toluene; 4.22 mL, 2.1 mmol) and 6 (0.3 g, 1.62 mmol) and
after purification by flash chromatography (basic alumina; hexane),
7 was obtained.
(1) (a) Molander, G. A.; Schmitt, M. H. J. Org. Chem. 2000, 65,
3767. (b) Beccalli, E. M.; Broggini, G.; La Rosa, C.;
Passarella, D.; Pilati, T.; Terraneo, A.; Zecchi, G. J. Org.
Chem. 2000, 65, 8924. (c) Ziegler, F. E.; Jeroncic, L. O. J.
Org. Chem. 1991, 56, 3479. (d) Jones, G. B.; Moody, C. J.;
Padwa, A.; Kassir, J. M. J. Chem. Soc., Perkin Trans. 1
1991, 1721. (e) Jones G. B., Moody C. J.; J. Chem. Soc.,
Perkin Trans. 1; 1989, 2449.
(2) Pérez-Serrano, L.; González-Pérez, P.; Casarrubios, L.;
Domínguez, G.; Pérez-Castells, J. Synlett 2000, 1303.
(3) Rosillo, M.; Casarrubios, L.; Domínguez, G.; Pérez-
Castells, J. Tetrahedron Lett. 2001, 42, 7029.
(4) (a) Dufour, B.; Motorina, I.; Fowler, F. W.; Grierson, D. S.
Heterocycles 1994, 37, 1455. (b) Eitel, M.; Pindur, U.
Heterocycles 1988, 27, 2353. (c) Pindur, U.; Kim, M.-H.
Tetrahedron Lett. 1988, 29, 3927. (d) Pindur, U.
Heterocycles 1988, 27, 1253.
Yield: 0.22 g (75%); colourless oil.
IR (neat): 3060, 2920, 1630 cm–1.
1H NMR (CDCl3): = 4.73–4.75 (m, 2 H), 4.87 (dd, 1 H, J 1 = 18.1,
1.1 Hz), 5.12 (dd, 1 H, J = 10.4, 1.1 Hz), 5.32 (dd, 1 H, J = 11.0,
1.6 Hz), 5.81 (dd, 1 H, J = 17.6, 1.6 Hz), 5.88–5.99 (m, 1 H), 6.66–
6.75 (m, 2 H), 7.08 (td, 1 H, J = 7.7, 1.1 Hz), 7.16 (td, 1 H, J = 8.2,
1.1 Hz) 7.24 (d, 1 H, J = 8.2 Hz), 7.58 (d, 1 H, J = 7.7 Hz).
13C NMR (CDCl3): = 138.1, 137.3, 133.2, 127.8, 125.7, 121.8,
120.5, 119.9, 116.4, 116.3, 109.4, 99.2, 45.4.
Anal. Calcd for C13H13N: C, 85.21; H, 7.15; N, 7.64. Found: C,
85.39; H, 7.29; N, 7.78.
(5) For the first synthesis of 2-vinylindole, see: Pindur, U.; Eitel,
M. Helv. Chim. Acta 1988, 71, 1060.
(6) Marco, J. L. J. Heterocycl. Chem. 1998, 475.
(7) Bergman, J.; Venemalm, L. J. Org. Chem. 1992, 57, 2495.
(8) Echavarren, A. M. J. Org. Chem. 1990, 55, 4255.
2-Trimethylsilanylethynyl-1H-indole (9)
The crude product obtained in the reaction of indole (1.17 g, 10.0
mmol) with BuLi (2.5 M in hexane; 4.2 mL), t-BuLi (1.7 M in pen-
tane; 6.2 mL) and 1,2-diiodoethane (2.82 g, 10.0 mmol) following
the method described by Bergman and Velemalm7 was dissolved in
toluene (25 mL). Then, a solution of Pd(PPh3)2Cl2 (0.34 g, 0.56
Synthesis 2002, No. 13, 1810–1812 ISSN 0039-7881 © Thieme Stuttgart · New York