7068
N. Sel6akumar et al. / Tetrahedron Letters 44 (2003) 7065–7069
trigger a new area of research among synthetic and
medicinal chemists to unravel the biological properties
of this group of alkaloids. The application of this
methodology to prepare a variety of 1-methoxyindoles
along with their corresponding indoles and their biolog-
ical evaluation is under progress in our laboratory. The
usefulness of this methodology is substantiated by a
direct total synthesis of 9-methoxycarbazole-3-carbalde-
hyde 1 in the following letter.15
(b) Experimental procedure for 10: A solution of the
nitro-diester 9 (500 mg, 1.5 mmol) in DMSO (10 mL) was
added using a syringe pump to a preheated (155°C, oil
bath temperature) and stirred solution of NaCl (255 mg,
4.4 mmol) in DMSO (10 mL) over 15 min. The resultant
mixture was further stirred for 30 min and then allowed
to cool to ambient temperature. The reaction mixture was
worked-up by adding water followed by extraction with
ethyl acetate. The combined organic extracts were washed
with water, brine and dried. The residue obtained upon
evaporation of the solvent was passed through a column
of silica gel to afford compound 10 (300 mg, 75%) as a
colorless oil, which became solid upon storage in a refrig-
erator. Further elution yielded the mono-decarboxylated
product (ca. 10%) as an oil. An analytical sample of
compound 10 was obtained by washing the solid with dry
hexane. Mp 80–82°C; IR (neat, w cm−1): 1699, 760; lH
(400 MHz, CDCl3): 8.26–8.23 (m, 1H), 7.67–7.29 (m,
8H), 3.79 (s, 3H), 3.72 (s, 3H); lC (50 MHz, CDCl3):
50.6, 64.8, 100.8, 108.3, 121.9, 122.4, 122.8, 123.3, 127.6
(2C), 128.3, 129.0, 130.5 (2C), 131.2, 141.3, 165.0. Mass
(CI): 282 (M++1), 250. Anal. calcd for C17H15NO3: C,
72.57; H, 5.38; N, 4.98; found: C, 72.37; H, 5.16; N, 5.25.
11. (a) Stauss, U.; Harter, H. P.; Neuenschwander, M.;
Schindler, O. Helv. Chim. Acta 1972, 55, 771; (b) Kondo,
Y.; Shiga, F.; Murata, N.; Sakamoto, T.; Yamanaka, H.
Tetrahedron 1994, 50, 11803; (c) Characterization data
for 11: mp 148°C (lit. mp 148–151°C);11a IR (neat, w
cm−1): 1699, 760; lH (200 MHz, CDCl3): 8.67 (bs, 1H),
8.23–8.18 (m, 1H), 7.67–7.25 (m, 8H), 3.83 (s, 3H); lC (50
MHz, CDCl3): 50.8, 104.1, 111.2, 122.0, 123.1, 127.4,
128.0 (2C), 128.8, 129.1, 129.5 (2C), 131.8, 135.2, 144.7,
166.0. Mass (CI): 252 (M++1), 220.
Acknowledgements
We thank Dr. K. Anji Reddy for his continued encour-
agement in this work. We would like to record our
special thanks to Dr. Sanjay Trehan for some useful
discussions. The help extended by Dr. R. Rajagopalan
is greatly acknowledged. We appreciate the services
extended by the Analytical Research department of
Discovery Research, Dr. Reddy’s Laboratories Ltd. for
this communication.
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14. Selected spectral data: 13: IR (neat, w cm−1): 1697,1439,
1212, 1114; lH (200 MHz, CDCl3): 8.15 (d, J=7.3 Hz,
1H), 7.69–7.26 (m, 4H), 6.40 (d, J=18.1 Hz, 1H), 5.75 (d,
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121.8, 121.7, 108.5, 100.7, 64.5, 50.9. Mass (CI): 232
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MHz, CDCl3): 8.12 (d, J=7.0 Hz, 1H), 7.43–7.23 (m,
4H), 7.03–6.91 (m, 1H), 3.95 (s, 3H), 3.94 (s, 3H), 2.06
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137.7, 134.7, 132.0, 123.3, 122.5, 122.2, 121.9, 118.5,
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10. (a) It is important to note that the starting material
should be added to a 155–160°C solution of NaCl in
DMSO. In cases where we heated all the reactants
together gradually from rt to 155°C, significant amounts
of decarboxylated products were isolated.