LETTER
New Synthesis of a Pyrroloquinoline Skeleton
1627
Stevenson, P. J.; Thompson, N. Tetrahedron Lett. 2001, 42,
6417. (h) Frank, K. E.; Aube, J. J. Org. Chem. 2000, 65,
655. (i) Nieman, J. A.; Ennis, M. D. Org. Lett. 2000, 2,
1395. (j) Nyerges, M.; Fejes, I.; Toke, L. Tetrahedron Lett.
2000, 41, 7951. (k) Snider, B. B.; Ahn, Y.; Foxman, B. M.
Tetrahedron Lett. 1999, 40, 3339. (l) Hadden, M.;
Stevenson, P. J. Tetrahedron Lett. 1999, 40, 1215.
(m) Batey, R. A.; Simoncic, P. D.; Lin, D.; Smyj, R. P.;
Lough, A. J. Chem. Commun. 1999, 651. (n) Lovely, C. J.;
Mahmud, H. Tetrahedron Lett. 1999, 40, 2079. (o) Kim, S.
S.; Cheon, H. G.; Kang, S. K.; Yum, E. K.; Choi, J. K.
Heterocycles 1998, 48, 221. (p) Gurjar, M. K.; Pal, S.; Rama
Rao, A. V. Heterocycles 1997, 45, 231. (q) Ho, T. C. T.;
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acid–ethanol to provide cyanomethyl ketone 25 in 88%
yield. 2,3-trans Arrangement of 25 was ambiguously con-
firmed by NMR spectra (J2,3 = 9.5 Hz). Reductive cy-
clization of 25 with Raney nickel (W-2) in ethanol under
refluxing conditions proceeded along with debenzylation
and unexpectedly resulted in cyclic imine 26 which was
easily converted to pyrroquinoline 277 in 58% yield from
25 after reduction with NaBH3CN in methanol followed
by N-protection with Boc2O (Scheme 4).
In summary, we have succeeded in preparation of ad-
vanced intermediate 27 in 34% overall yield from 17
towards the synthesis of martinelline taking advantage of
the Michael–aldol strategy.
(3) (a) Ma, D.; Xia, C.; Jiang, J.; Zhang, J.; Tang, W. J. Org.
Chem. 2003, 68, 442. (b) Xia, C.; Heng, L.; Ma, D.
Tetrahedron Lett. 2002, 43, 9405. (c) Powell, D. A.; Batey,
R. A. Org. Lett. 2002, 4, 2913. (d) Ma, D.; Xia, C.; Jiang, J.;
Zhang, J. Org. Lett. 2001, 3, 2189. (e) Snider, B. B.; Ahn,
Y.; O’Hare, S. M. Org. Lett. 2001, 3, 4217.
(4) Makino, K.; Hara, O.; Takiguchi, Y.; Katano, T.; Asakawa,
Y.; Hatano, K.; Hamada, Y. Tetrahedron Lett. 2003, 44,
8925.
Acknowledgment
This work was financially supported in part by a Grant-in-Aid for
Scientific Research (C) from the Ministry of Education, Culture,
Sports, Science, and Technology, Japan.
(5) List, B.; Lerner, R. A.; Barbas, C. F. I. I. I. J. Am. Chem. Soc.
2000, 122, 2395.
References
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(2) (a) He, Y.; Mahmud, H.; Wayland, B. R.; Dias, H. V. R.;
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(7) Compound 27: amorphous powder. IR (KBr): 3389, 2979,
1700, 1685, 1559, 1458 cm–1. 1H NMR (CDCl3, 55 °C): d =
1.09–1.19 (m, 1 H), 1.23–1.43 (m, 22 H), 1.62–1.75 (m, 3
H), 2.37 (s, 3 H), 3.08–3.22 (m, 4 H), 4.51–4.55 (m, 2 H),
6.45 (m, 1 H), 6.54 (d, J = 2.7 Hz, 1 H), 6.73 (dd, J = 8.5, 2.4
Hz, 1 H), 7.19 (d, J = 8.1 Hz, 2 H), 7.34 (d, J = 8.5 Hz, 1 H),
7.48 (d, J = 8.1 Hz, 2 H). 13C NMR (CDCl3, 55 °C): d = 21.4,
27.1, 28.5, 54.1, 80.0, 112.9, 114.9, 125.3, 126.9, 129.9,
130.4, 136.4, 155.7, 156.3. HRMS-FAB: m/z calcd for
C31H43O7N3S: 601.2822 [M+ + 1]. Found: 601.2792
[M+ + 1].
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(g) Hadden, M.; Nieuwenhuyzen, M.; Osborne, D.;
Synlett 2004, No. 9, 1625–1627 © Thieme Stuttgart · New York