A. Ardeo et al. / Tetrahedron Letters 44 (2003) 8445–8448
8447
2. For reviews, see: (a) de Koning, H.; Speckamp, W. N. In
Stereoselective Synthesis [Houben-Weyl], Helmchen, G.;
Hoffmann, R. W.; Muzler, J.; Schaumann, E., Eds.;
Thieme: Stuttgart, 1996, Workbench ed. E21, Vol. 3,
1952–2010; (b) See also Ref. 1.
3. For some recent examples, see: (a) Luker, T.; Koot,
W.-J.; Hiemstra, H.; Speckamp, W. N. J. Org. Chem.
1998, 63, 220–221; (b) Padwa, A.; Heidelbaugh, T. M.;
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4. For some representative examples, see: (a) Speckamp, W.
N. Rec. Trav. Chim. Pays-Bas. 1981, 345–354; (b)
Maryanoff, B. E.; McComsey, D. F.; Duhl-Emswiler, B.
A. J. Org. Chem. 1983, 48, 5062–5074; (c) Kano, S.;
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D. F.; Almond, H. R., Jr.; Mutter, M. S. J. Org. Chem.
1986, 51, 1341–1346; (e) Ent, H.; Koning, H.; Speckamp,
W. N. Heterocycles 1988, 27, 237–243; (f) Bahajaj, A. A.;
Vernon, J. M.; Wilson, G. D. J. Chem. Soc. Perkin Trans.
2001, 1446–1451; (g) Katritzky, A. R.; Mehta, S.; He,
H.-Y. J. Org. Chem. 2001, 66, 148–152.
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Villa, M. J. Synlett 1993, 41–42; (b) Collado, M. I.;
Sotomayor, N.; Villa, M. J.; Lete, E. Tetrahedron Lett.
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62, 2080–2092; (d) Osante, I.; Garc´ıa, E.; Ardeo, A.;
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Scheme 3. Reagents: (a) LiBH4, TMSCl, THF; (b) TBDPSCl,
imidazole; (c) succinic anhydride, Et2O, reflux; then NaOAc,
Ac2O; (d) MeLi (4 equiv.), THF, −78°C; (e) BF3·OEt2,
CH2Cl2, reflux.
position. This result is consistent with our previous
results in the synthesis of pyrroloisoquinolines,7 and
with the results reported by Allin,11 and could be
explained by a balance between A(1,3) strain and syn-
axial 1,3-interactions, favouring the pseudo-equatorial
disposition of the C-5 substituent in the transition state
(Scheme 3).
In conclusion, the stereoselective synthesis of enan-
tiomerically pure indolo[2,3-a]indolizidinones is feasible
via a diastereoselective a-amidoalkylation reaction that
leads to the 5S,11bS-trans diastereomer. This result
illustrates the influence of the nature of the substituent
on C-11b. Thus, in the synthesis of related b-carboline
derivatives with no substitution on C-11b, cis
diastereomers in which the substituent a to nitrogen is
in an axial orientation are preferentially formed.17
6. (a) Osante, I.; Collado, M. I.; Lete, E.; Sotomayor, N.
Synlett 2000, 101–103; (b) Osante, I.; Collado, M. I.;
Lete, E.; Sotomayor, N. Eur. J. Org. Chem. 2001, 1267–
1277.
7. Garc´ıa, E.; Arrasate, S.; Ardeo, A.; Lete, E.; Sotomayor,
N. Tetrahedron Lett. 2001, 42, 1511–1513.
8. Gonza´lez-Temprano, I.; Sotomayor, N.; Lete, E. Synlett
2002, 593–597.
Acknowledgements
9. (a) Allin, S. M.; James, S. L.; Martin, W. P.; Smith, T. A.
D. Tetrahedron Lett. 2001, 42, 3943–3946; (b) Allin, S.
M.; James, S. L.; Martin, W. P.; Smith, T. A. D.;
Elsegood, M. R. J. J. Chem. Soc., Perkin Trans. 1 2001,
3029–3036.
Financial support from Gobierno Vasco (PI-1999-165),
MCYT (BQU2000-0223), and Universidad del Pa´ıs
Vasco is gratefully acknowledged. We also thank the
Gobierno Vasco for grants (A.A., E.G.).
10. This work was presented in part at the 12th European
Symposium on Organic Chemistry (ESOC-12), Gronin-
gen, The Netherlands, July 13-18, 2001, see book of
abstracts: communication P2-160.
11. Allin, S. M.; Thomas, C. I.; Allard, J. E.; Duncton, M.;
Elsegood, M. R. J.; Edgar, M. Tetrahedron Lett. 2003,
44, 2335–2337.
12. (a) Narayanan, K.; Cook, J. M. Tetrahedron Lett. 1990,
31, 3397–3400; (b) Narayanan, K.; Cook, J. M. J. Org.
Chem. 1991, 56, 5733–5736.
13. Padwa, A.; Waterson, A. G. Tetrahedron 2000, 56,
10159–10173.
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