A. K. Mohanakrishnan, P. Amaladass / Tetrahedron Letters 46 (2005) 4225–4229
4229
R. H. L.; Adriaensens, P. J. A.; Vanderzande, D. J. N.;
Gelan, J. M. J. V. J. Org. Chem. 1997, 62, 1473–1480.
9. Mohanakrishnan, A. K.; Lakshmikantham, M. V.;
McDougal, C. D.; Cava, M. P.; Baldwin, J. W.; Metzger,
R. M. J. Org. Chem. 1998, 63, 3105–3112.
10. Raimundo, J. M.; Blanchard, P.; Brisset, H.; Akoudad, S.;
Roncali, J. Chem. Commun. 2000, 939–940.
11. Strassler, C.; Davis, N. E.; Kool, E. T. Helv. Chim. Acta
1999, 82, 2160–2171.
12. Tan, S.; Bhowmik, A. K.; Thakur, M.; Lakshmikantham,
M. V.; Cava, M. P. J. Chem. Phys. 2000, 112, 383–385.
13. (a) Cowell, A.; Stille, J. K. J. Am. Chem. Soc. 1980, 102,
4193–4198; (b) Negishi, E. T.; Conperet, C.; Ma, S.; Lion,
S. Y.; Liu, F. Chem. Rev. 1996, 96, 365–393; (c) Ojima, I.;
Tzamarionadki, N.; Li, Z.; Donoban, R. J. Chem. Rev.
1996, 96, 635–662; (d) Kitagawa, K.; Inoue, A.; Shin-
okubo, H.; Oshima, K. Angew. Chem. 2000, 39, 2481–
2483; (e) Kondo, Y.; Asai, M.; Miura, T.; Uchiyama, M.;
Sakamoto, T. Org. Lett. 2001, 3, 13–15; (f) Inoue, A.;
Kitagawa, K.; Shinokubo, H.; Oshima, K. J. Org. Chem.
2001, 66, 4333–4339; (g) Lei, J. G.; Hung, R.; Yuan, S. G.;
Lin, G. K. Synlett 2002, 927–930; (h) Yang, X.; Rotter, T.;
Piazza, C.; Knochel, P. Org. Lett. 2003, 5, 1229–1231.
14. Rayabarapu, D.; Chang, H. T.; Cheng, C. H. Chem. Eur.
J. 2004, 10, 2991–2996.
1.71 mL, 17.72 mmol) and Mg (0.510 g, 21.27 mmol) were
added to a solution of phthalide 3d (5 g, 16.12 mmol) at
0 ꢁC. After the addition was complete, the reaction
mixture was poured into an ice-cooled NH4Cl solution,
and extracted with CH2Cl2 (100 mL) and dried (Na2SO4).
The solution was treated with LawessonÕs reagent (3.26 g,
8.05 mmol) and stirred at room temperature overnight.
The solvent was removed and the residue was gently
heated on a steam bath with ethanol. The crude product
was purified by column chromatography (neutral alumina,
hexane) to afford benzo[c]thiophene 4g as a yellow solid
(4.1 g, 65%).
Spectral data of some selected benzo[c]thiophenes: For 4a:
1
mp 107 ꢁC; H NMR (400 MHz, CDCl3): d 3.91 (s, 3H),
7.03 (d, J = 8.8 Hz, 2H), 7.05–7.16 (m, 3H), 7.33–7.36 (m,
2H), 7.59 (d, J = 8.8 Hz, 2H), 7.74 (d, J = 8.8 Hz, 1H),
7.95 (d, J = 8.76 Hz, 1H). 13C NMR (75 MHz, CDCl3): d
55.64, 114.80, 121.54, 124.30, 124.79, 125.34, 125.42,
126.20, 128.04, 130.70, 132.21, 134.37, 135.15, 136.24,
159.63. MS(EI) m/z (%): 322(M+, 100), 307(93), 279(32),
195(43), 161(45), 77(14). Elemental Anal. Calcd for
C19H14OS2: C, 70.77; H, 4.38; S, 19.89%. Found: C,
70.60; H, 4.36; S, 19.80%.
1
For 4c: mp 170 ꢁC; H NMR (400 MHz, CDCl3): d 6.92–
7.01 (m, 3H), 7.12 (dd, J = 3.68 Hz, J = 1.44 Hz, 1H), 7.29
(d, J = 3.88 Hz, 1H), 7.42–7.56 (m, 5H), 7.85 (d,
J = 9.28 Hz, 1H), 8.00 (d, J = 8.8 Hz, 2H), 8.06 (d,
J = 8.32 Hz, 2H), 8.62 (s, 1H). MS(EI) m/z (%): 392(M+,
5), 375(100), 351(26), 301(15), 264(29), 233(42), 154(27).
Elemental Anal. Calcd for C26H16S2: C, 79.55; H, 4.11; S,
16.34%. Found: C, 79.46; H, 4.18; S, 16.36%.
15. Jensen, A. E.; Dohle, W.; Sapountzis, I.; Lindsay, D. M.;
Au, V. A.; Knochel, P. Synthesis 2002, 4, 565–569.
16. Kato, S.; Nonoyama, N.; Tomimoto, K.; Mase, T.
Tetrahedron Lett. 2002, 43, 7315–7317.
17. Wheeler, D. D.; Young, D. C.; Erley, D. S. J. Org. Chem.
1956, 22, 547–556.
18. X-ray data for the X-ray data for compound 4i: X-ray
data were collected at 293(2) K on a ENRAF NONIUS-
CAD4 diffractometer with graphite monochromated
For 4g: mp 80 ꢁC; 1H NMR (300 MHz, CDCl3): d 0.90 (t,
J = 6.1 Hz, 3H), 1.32–1.51 (m, 6H), 1.77 (quin, J = 7.1 Hz,
2H), 3.94 (t, J = 6.25 Hz, 2H), 6.94–7.09 (m, 5H), 7.28 (d,
J = 4.04 Hz, 2H), 7.52 (d, J = 8.24 Hz, 2H), 7.72 (d,
J = 8.45 Hz, 1H), 7.92 (d, J = 8.45 Hz, 1H). 13C NMR
(75 MHz, CDCl3): d 14.04, 22.58, 25.69, 29.18, 31.55,
68.05,114.98, 121.27, 123.93, 124.94, 125.01, 126.61,
127.01, 127.71, 130.30, 134.20, 135.15, 135.81, 136.24,
158. 87. MS(EI) m/z (%): 392 (M+, 49), 346(14), 281(100),
239(55), 223(43), 137(62), 104(59). Elemental Anal. Calcd
for C24H24OS2: C, 73.43; H, 6.16; S, 16.34%. Found: C,
73.35; H, 6.14; S, 16.29%.
˚
Mo-Ka radiation (k = 0.71073 A). The structure was
solved by direct methods (SHELX-97). Refinement was
done by full-matrix least-squares procedures on F2 using
SHELX-97. All non-hydrogen atoms were refined aniso-
tropically. C22H18O2S, MW = 346, yellow crystal of size:
0.30 · 0.22 · 0.28 mm3, crystal system: orthorhombic,
˚
cell parameters: a = 7.508(6) A,
space group: Pcab
,
3
˚
˚
˚
b = 16.493(9) A, C = 27.952(9) A, V = 3461(4) A , Z = 8,
Dc = 1.330 mg/m3, T = 293(2) K, l(Mo-Ka) = 0.199
mmÀ1, F000 = 1456, total number of l.s. parameters = 228,
R1 = 0.0580 for 3579 I > 2r(I) and 0.0955 for all 5044
data. WR2 = 0.1716, GOF = 1.043 for all data. Crystallo-
graphic data (excluding structure factors) for 4i have been
deposited with the Cambridge Crystallographic Data
Center as supplementary publication number CCDC
268130. Copies of the data may be obtained, free of
charge, on application to CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: +44(0)-1223-33603 or
e-mail: deposit@ccdc.cam.ac.uk).
1
For 4h: mp 116 ꢁC; H NMR (400 MHz, CDCl3): d 7.17–
7.24 (m, 4H), 7.40 (dd, J = 2.44 Hz, J = 1.22 Hz, 1H), 7.44
(d, J = 4.88 Hz, 1H), 7.83 (d, J = 9.28 Hz, 2H), 8.02 (d,
J = 2.44 Hz, 1H), 8.34 (d, J = 8.8 Hz, 2H). MS(EI) m/z
(%): 338 (M+1+, 100), 292(69), 228(42), 123(36), 82(29).
Elemental Anal. Calcd for C18H11NO2S2: C, 64.07; H,
3.29; N, 4.15; S, 19.01%. Found: C, 64.03; H, 3.33; N,
4.12; S, 18.95%.
For 4j: mp 118 ꢁC; 1H NMR (400 MHz, CDCl3): d 2.42 (s,
6H), 7.05 (dd, J = 3.44 Hz, J = 3.4 Hz, 2H), 7.29 (d,
J = 7.8 Hz, 4H), 7.57 (d, J = 7.8 Hz, 4H), 7.80 (dd,
J = 3.92 Hz, J = 2.92 Hz, 2H). 13C NMR (75 MHz,
CDCl3): d 21.22, 121.20, 123.93, 129.08, 129.70, 131.46,
133.83, 134.99, 137.29. MS(EI) m/z (%): 314(M+,100),
298(18), 283(20), 208(17), 157(35), 77(12). Elemental Anal.
Calcd for C22H18S: C, 84.03; H, 5.77; S, 10.20%. Found:
C, 83.83; H, 5.83; S, 10.34%.
19. The aryl Grignards reagents were prepared from the
corresponding bromo compounds by refluxing with
magnesium in dry THF under N2 atmosphere.
20. All benzo[c]thiophene analogs 4a–l gave satisfactory
spectral and analytical data.
A representative procedure for 4g: Freshly prepared thienyl
magnesium bromide (from 2-bromothiophene, 2.89 g