H. Ishikawa et al. / Tetrahedron Letters 43 (2002) 5637–5639
5639
mixture of carbamates, without purification, was
reduced with Red-Al in toluene to afford meso-chimo-
nanthine (9, 30% yield) and rac-chimonanthine (10,
13% yield), together with a dimeric compound (11, 23%
yield) and Nb-methyltryptamine (9% yield). The syn-
thetic rac-chimonanthine (10, mp 178–180°C) was
directly compared with the natural product that was
isolated from Calycanthus praecox in our laboratory.
The spectral data of synthetic 9 (mp 199–202°C) agreed
with those in the literature.13a The structure of dimer 11
(mp 119–123°C) was inferred from spectral data, partic-
ularly, by observations of HMBC correlations and
NOEs as shown in Fig. 1.
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A. J., Jr.; Chou, T. T. Heterocycles 1986, 24, 669–678.
7. Crystal data for 6b (mp 149–155°C). Data were acquired
with a CCD diffractometer with Mo–Ka radiation (u=
Further application of this type of reaction to the
synthesis of natural indole alkaloids is in progress.
,
0.71069 A), graphite monochromated, monoclinic,
Acknowledgements
C24H24N2 (Mw: 340.47), space group P21/n with a=
,
,
,
12.056 (2) A, b=12.466 (2) A, c=12.073 (2) A, i=
3
,
102.487 (2) °, V=1771.6 (4) A , Z=4, and Dcalc=1.276
The authors are indebted to Professor Dr. Kentaro
Yamaguchi, Analysis Center of Chiba University, for
X-ray crystallographic analysis. This work was sup-
ported in part by a Grant-in-Aid (No. 14370718) for
Scientific Research from the Ministry of Education,
Culture, Sports, Science and Technology, Japan, and
JSPS Research Fellowship for Young Scientists to H.I.
g/cm3. The final R value was 0.039 (Rw=0.048) for 2521
reflections (I>3|(I)).
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Chem. Soc. 1961, 465–466; (b) Hall, E. S.; McCapra, F.;
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