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2. Magnier, E.; Langlois, Y. Tetrahedron Lett. 1995, 36, 9475.
3. Magnier, E.; Langlois, Y. Tetrahedron Lett. 1998, 39, 837.
4. (a) Chen, T.-K.; Bradsher, C. K. J. Org. Chem. 1979, 44, 4680–4683. (b) Manna, S.; Falk, J. R.; Mioskowski, C.
J. Org. Chem. 1982, 47, 5021–5023. (c) Falk, J. R.; Manna, S.; Mioskowski, C. J. Am. Chem. Soc. 1982, 105,
631–633. (d) Gupta, R. B.; Frank, R. W. J. Am. Chem. Soc. 1987, 109, 5393–5403. (e) Gupta, R. B.; Franck, R.
W.; Onan, K. D.; Soll, C. E. J. Org. Chem. 1989, 54, 1097–1101. (f) Bolitt, V.; Mioskowski, C.; Kollah, R. O.;
Manna, S.; Rajapaksa, D.; Falk, J. R. J. Am. Chem. Soc. 1991, 113, 6320–6321. (g) Yin, H.; Frank, R. W.; Chen,
S.-L.; Quigley, G. J.; Todaro, L. J. Org. Chem. 1992, 57, 644–651.
5. Sageot, O.; Monteux, D.; Langlois, Y.; Riche, C.; Chiaroni, A. Tetrahedron Lett. 1996, 37, 7019.
6. For a precedent example of asymmetric Bradsher cycloaddition, see: Choudury, A.; Frank, R. W.; Gupta, R. B.
Tetrahedron Lett. 1989, 37, 4921–4924.
7. Gnecco, D.; Marazano, C.; Das, B. C. J. Chem. Soc., Chem. Commun. 1991, 625–626 and references cited therein.
8. Benhida, R.; Devys, M.; Fourrey, J.-L.; Lecubin, F.; Sun, J.-S. Tetrahedron Lett. 1998, 39, 6167–6170.
9. (S)- or (R)-serine were used indifferently as starting material.
10. Sugano, H.; Miyashi, M. J. Org. Chem. 1976, 41, 2352–2353.
11. Pansare, S. V.; Arnold, L. D.; Vederas, J. C. Org. Synth. 1991, 70, 10–17.
12. Sakai, M.; Hashimoto, K.; Shirahama, H. Heterocycles 1997, 44, 319–324.
13. Purification by chromatography on silica gel induced a nucleophilic attack of the hydroxy group on C1 affording
an unstable dihydronaphthyridine intermediate.
14. Duval, E.; Zoltobroda, G.; Langlois, Y. Tetrahedron Lett. 2000, 41, 337–339.
15. Yields were calculated from 2,7-naphthyridine 2 for two steps: Zincke reaction and Bradsher cycloaddition.
16. Compound 25 in which the primary alcohol is silylated gave significantly lower yield in these cycloadditions.
17. Racemic 28a was obtained by benzylation of the known corresponding adduct resulting from a cycloaddition
between compounds 3 and 17. Racemic adduct 4 was correlated in two steps with adduct 30a (mesylation,
nucleophilic displacement of the mesylate intermediate with PhSe−).
18. Racemisation during salt 14 formation seems unlikely, see for other examples Ref. 7.
19. In the previous case3 of naphthyridinium salt 3, adduct 4 is the only product of the reaction. The same steric
hindrance probably induced the nucleophilic attack of only the pro R* primary alcohol on the iminium
intermediate.
.