An Alternative Procedure for the Synthesis of [5]- and [7]Carbohelicenes
FULL PAPER
NMR (CDCl3): δ ϭ 7.26 (ddd, J ϭ 8.4, J ϭ 6.8, J ϭ 2.0 Hz, 1 H, [7]Helicene (5a) was obtained from 3a in 90% yield after chroma-
13-H), 7.47 (ddd, J ϭ 8.0, J ϭ 7.0, J ϭ 1.2 Hz, 1 H, 12-H), 7.52 tography with cyclohexane/ethyl acetate (99:1) as the eluent. NMR
(d, J ϭ 2.0 Hz, 1 H), 7.7Ϫ7.9 (8 H), 8.43 (d, J ϭ 8.4 Hz, 14-H), spectroscopic data are in agreement with those previously report-
8.61 (s, 1-H); 118.6 (C-Br), 124.6, 126.0, 126.3, 126.6, 126.9, 127.0,
127.8, 127.9, 128.0, 128.5, 129.4, 130.2, 131.2, 132.0 (C), 132.3 (C),
132.6 (C) ppm.
ed.[7a,20]
2,17-Dimethyl[7]helicene (5c) was obtained from 3c in 70% yield
(140 mg) after chromatography with cyclohexane/ethyl acetate
(90:10) as the eluent (Rf ϭ 0.7). Mass spectrum (E.I.): m/z ϭ 406
2-Bromo-13-methoxy[5]helicene (4b) was obtained from 2b in 68%
yield (0.13 g) after chromatography with cyclohexane/ethyl acetate
(90:10) as the eluent (Rf ϭ 0.6). Colourless solid. M.p. 165 °C.
Mass spectrum (E.I.): m/z ϭ 386 (M, 79Br, 35%), 276 (73%), 263
(65%), 131 (100%). 1H NMR (CDCl3): δ ϭ 3.52 (s, OMe), 7.13
(dd, J ϭ 8.8, J ϭ 2.6 Hz, 12-H), 7.50 (dd, J ϭ 8.6, J ϭ 1.8 Hz, 1
H), 7.6Ϫ7.9 (m, 9 H), 8.60 (d, J ϭ 1.6 Hz, 1-H) ppm. 13C NMR
(CDCl3): δ ϭ 55.0 (OMe), 108.7 (CH-o-OMe), 118.3 (C-Br), 118.6
(CH-o-OMe), 124.0, 126.0 (C), 126.7, 127.0, 127.5, 127.9 (C),
128.2, 129.1, 129.5, 129.6, 131.0 (C), 131.4 (C), 131.5 (C), 131.8,
132.6 (C), 132.9 (C), 156.9 (C-OMe) ppm. C23H15BrO (384.27):
calcd. C 71.33, H 3.90; found C 71.05, H, 4.05.
1
[M] (63%), 187 (100%). H NMR (CDCl3): δ ϭ 1.77 (s, 6 H, Me),
6.75 (dd, J ϭ 8.1, J ϭ 1 Hz, 2 H, 3-H, 16-H), 6.94 (d, J ϭ 1 Hz, 2
H, 1-H, 18-H), 7.22 (d, J ϭ 8.0 Hz, 2 H, 4-H, 15-H), 7.49 (AB,
J ϭ 8.5 Hz, 2 H), 7.67 (AB, J ϭ 8.5 Hz, 2 H), 7.93 (AB, J ϭ 8.2 Hz,
2 H), 8.00 (AB, J ϭ 8.2 Hz, 2 H), 8.03 (s, 2 H, 9-H, 10-H) ppm.
13C NMR (CDCl3) δ ϭ 20.1 (Me) 123.6, 123.9, 124.2 (C), 125.2,
125.5, 125.7, 125.8, 126.3, 127.2 (C), 128.2 (C), 128.9 (C), 130.0
(C), 130.7 (C),132.6 (C) ppm.
2-Methoxy[7]helicene (5d) was obtained from 3d in 89% yield
(180 mg) after chromatography with cyclohexane/ethyl acetate as
the eluent (Rf ϭ 0.5). Mass spectrum (E.I.): m/z ϭ 408 [M] (100%).
1H NMR (CDCl3): δ ϭ 3.04 (s, 3 H, OMe), 6.32 (ddd, J ϭ 8.4,
J ϭ 7.0, J ϭ 1.4 Hz, 1 H, 17-H), 6.5 (m, 2 H), 6.84 (ddd, J ϭ 8.0,
J ϭ 7.0, J ϭ 1.2 Hz, 1 H, 16-H), 7.02 (d, J ϭ 8.6 Hz, 1 H), 7.13
(d, J ϭ 8.6 Hz, 1 H), 7.27 (d, J ϭ 7.2 Hz, 1 H), 7.38 (d, J ϭ 8.4 Hz,
1 H), 7.50 (d, J ϭ 8.4 Hz, 1 H), 7.56 (d, J ϭ 8.4 Hz, 1 H), 7.67 (d,
J ϭ 8.4 Hz, 1 H), 7.81 (AB, J ϭ 8.1 Hz, 1 H), 7.84 (d, J ϭ 8.1 Hz,
1 H), 7.90 (AB, J ϭ 8.1 Hz, 1 H), 7.93 (d, J ϭ 8.4 Hz, 1 H), 7.95
(s, 2 H) ppm. 13C NMR (CDCl3) selected data: δ ϭ 52.8 (OMe),
103.4 (CH-3), 115.9 (CH-1), 155.4 (C-OMe) ppm.
2-Bromo-13-cyano[5]helicene (4c) was obtained from 2c in 62%
yield (0.12 g) after chromatography with cyclohexane/ethyl acetate
(90:10) as the eluent (Rf ϭ 0.4). Colourless solid. M.p. 288 °C.
1
Mass spectrum (E.I.): m/z ϭ 381 [M, 79Br] (30%), 301 (100%). H
NMR (CDCl3): δ ϭ 7.56 (dd, J ϭ 8.6, J ϭ 1.8 Hz, 1 H), 7.61 (dd,
J ϭ 8.4, J ϭ 1.6 Hz, 1 H), 7.7Ϫ8.0 (m, 8 H), 8.45 (d, J ϭ 1.6 Hz,
1-H), 8.79 (d, J ϭ 0.8 Hz, 14-H) ppm. 13C NMR (CDCl3): δ ϭ
107.8 (C-CN), 119.1 (C-Br), 119.4 (C), 125.4 (C), 126.2 (C), 126.7,
127.0, 127.4, 127.7, 127.8, 128.4, 129.2, 129.6, 129.8, 130.1, 130.3
131.2 (C), 131.4 (C), 132.7 (C), 133.0 (C), 133.8, 134.4 (C) ppm.
C23H12BrN (382.25): calcd. C 72.27, H 3.16; found C 72.12, H 3.84.
Acknowledgments
2-Bromo-13-methyl[5]helicene (4d) was obtained from 2d in 95%
yield (0.18 g) after chromatography with cyclohexane/ethyl acetate
(95:5) as the eluent (Rf ϭ 0.6). Colourless solid. M. p. 161 °C. Mass
spectrum (E.I.): m/z ϭ 370 [M, 79Br] (40%), 276 (93%), 138 (100%).
1H NMR (CDCl3): δ ϭ 7.29 (dd, J ϭ 8.0, J ϭ 1.4 Hz, 1 H), 7.49
(dd, J ϭ 8.6, J ϭ 2.0 Hz, 1 H), 7.6Ϫ7.8 (8 H), 8.22 (d, J ϭ 0.6 Hz,
1 H, 14-H), 8.64 (d, J ϭ 1.6 Hz, 1 H, 1-H) ppm. 13C NMR
(CDCl3): δ ϭ 21.7 (Me), 118.3 (C-Br), 125.4, 126.1 (C), 126.5 (C),
126.8, 127.0, 127.6, 127.9, 128.0, 128.3, 128.5, 129.2, 129.3, 130.3
(C), 130.8 (C), 131.0 (C), 131.4, 131.9 (C), 132.6, 134.5 ppm.
´
The authors are grateful to CMCU (Comite Mixte Franco-Tunis-
´
ien pour la Cooperation Universitaire) and EGIDE for financial
support and grants to R. E. A.
[1] [1a]
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2-Bromo-13-hydroxy[5]helicene (4f) was obtained from 2f in 73%
yield (0.15 g) after chromatography with cyclohexane/ethyl acetate
(70:30) as the eluent (Rf ϭ 0.6). Colourless solid. Mass spectrum
(E.I.): m/z ϭ 372 [M, 79Br] (17%), 293 [M Ϫ Br] (87%), 275 (100%).
1H NMR (CDCl3): δ ϭ 5.9 (OH), 7.19 (dd, J ϭ 8.7, J ϭ 2.3 Hz,
1 H, CH-o-OH), 7.56 (dd, J ϭ 8.5, J ϭ 1.9 Hz, 1 H), 7.71 (AB,
J ϭ 8.5 Hz, 1 H), 7.76 (AB, J ϭ 8.5 Hz, 1 H), 7.8Ϫ7.9 (7 H), 8.74
(d, J ϭ 1.5 Hz, 1 H, 1-H) ppm. 13C NMR (CDCl3): δ ϭ 112.2
(C12), 117.4 (C14), 118.4 (C-Br), 123.9, 125.8 (C), 126.1 (C), 126.7,
127.0, 127.1, 127.6, 127.8 (C), 128.0, 129.2, 129.4, 129.9, 131.1 (C),
131.5, 131.7 (C), 132.5 (C), 132.9 (C), 153.1 (C-OH) ppm.
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[2a]
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9-Bromo-1,3-dimethoxydibenzo[a,h]anthracene (6) was obtained
from 4e in 43% yield (90 mg) after chromatography with cyclohex-
ane/ethyl acetate (90:10) as the eluent (Rf ϭ 0.3). Colourless solid.
Mass spectrum (E.I.): m/z ϭ 416 [M] (78%), 322 (71%), 125 (100%).
1H NMR (CDCl3): δ ϭ 3.99 (s, OMe), 4.19 (s, OMe), 6.84 (d, J ϭ
2.4 Hz, 2-H), 6.94 (d, J ϭ 2.5 Hz, 4-H), 7.5Ϫ7.7 (m, 4 H), 7.90 (d,
J ϭ 8.9 Hz, 1 H), 7.94 (d, J ϭ 8.9 Hz, 1 H), 8.92Ϫ8.94 (2 H, 7-H,
8-H), 9.99 (s, 1 H, 14-H) ppm. 13C NMR (CDCl3) selected data:
δ ϭ 55.6 (OMe), 55.9 (OMe), 99.4 (CH-o-MeO), 102.3 (CH-o-
MeO) ppm.
[2g]
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[4]
Soc. Chim. Belg. 1986, 95, 547Ϫ556.
[4a]
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Eur. J. Org. Chem. 2004, 1517Ϫ1522
2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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