1. Synthesis of Daphnilongeranine C
A synthethic route presented
by Lab B members :
Guillaume Pelletier, Gérald Lemonnier, Philipp Gritsch,
William S. Bechara, Léa Constantineau-Forget and Alexandra Aubé
May 14th 2010

2. Background on the Natural Molecule
Isolated from Daphniphyllum longeracemosum, an evergreen tree in the Yunnan Province of China
2 quarternary and 5 tertiary centers
1 tertiary amine
8 stereogenic centers
Hexacyclic sytem

3. Retrosynthetic analysis

4. Retrosynthetic analysis

5. Synthesis of the cyclohexenone core
a) Funk, R.L.; Bolton, G. L. J. Org. Chem , 52, b) Evans, D. A.; Bender, S. L. Tetrahedron Lett. 1986, 27, 799.

6. Synthesis of the cyclohexenone core
a) Funk, R.L.; Bolton, G. L. J. Org. Chem , 52, b) Evans, D. A.; Bender, S. L. Tetrahedron Lett. 1986, 27, 799.

7. Synthesis of the cyclohexenone core
a) Funk, R.L.; Bolton, G. L. J. Org. Chem , 52, b) Evans, D. A.; Bender, S. L. Tetrahedron Lett. 1986, 27, 799.

8. Synthesis of the cyclohexenone core

9. Synthesis of the cyclohexenone core
a) Kanematsu, M. et al. Synthesis 2009, 17, b) Fischer, C.; Fu, G.C. J. Am. Chem. Soc. 2005, 127, c) Rudolph, A.; Lautens, M. Angew. Chem. Int. Ed. 2009, 48, 2. d) Genicot, C.; Gobeaux, B.; Ghosez, L. Tetrahedron Lett. 1991, 32, 3827.

10. Synthesis of the cyclohexenone core (alternative)
a) Kanematsu, M. et al. Synthesis 2009, 17, b) Fischer, C.; Fu, G.C. J. Am. Chem. Soc. 2005, 127, c) Rudolph, A.; Lautens, M. Angew. Chem. Int. Ed. 2009, 48, 2. d) Genicot, C.; Gobeaux, B.; Ghosez, L. Tetrahedron Lett. 1991, 32, 3827.

11. Intramolecular [2+2] on a keteniminium intermediate
Genicot, C.; Gobeaux, B.; Ghosez, L. Tetrahedron Lett. 1991, 32, 3827.

12. Ring expansion via an intramolecular Schmidt reaction
a) Martinelli, M. J.; et al. Tetrahedron Lett. 2000, 41, b) Zhen, Z. B. et al J. Org. Chem , 73, 7310
c) Zeng, Y.; Aubé, J. J. Am. Chem. Soc. 2005, 127,

13. Ring expansion via an intramolecular Schmidt reaction
Zeng, Y.; Aubé, J. J. Am. Chem. Soc. 2005, 127,

14. Synthesis of the cyclopentene core
a) Babler, J. H. et al. Synth. Commun. 1996, 26, b) Kvita, V. et al. Helv. Chem. Acta 1990, 73, 883.

15. Synthesis of the cyclopentene core
a) Babler, J. H. et al. Synth. Commun. 1996, 26, b) Kvita, V. et al. Helv. Chem. Acta 1990, 73, 883.
c) Marko, I. E. et al. Tetrahedron Lett. 1994, 35, d) Marko, I. E. et al Org. Lett. 2000, 2, 2123.

16. Radical-mediated ring fragmentation
c) Marko, I. E. et al. Tetrahedron Lett. 1994, 35, d) Marko, I. E. et al Org. Lett. 2000, 2, 2123.

17. Radical-mediated ring fragmentation
c) Marko, I. E. et al. Tetrahedron Lett. 1994, 35, d) Marko, I. E. et al Org. Lett. 2000, 2, 2123.

18. Synthesis of the cyclopentene core
a) Kende, A. S. et al. J. Am. Chem. Soc. 1990, 112, c) Kazahawa, K. et al. Synlett 2004, 1640.
d) Paquette, L. E. et al. J. Org. Chem. 1996, 61, 3268.

19. Synthesis of the cyclopentene core
a) Paquette, L. E. et al. J. Org. Chem. 1996, 61, b) Hoye, T. R.; Caruso, A. J. Dellaria, J. F.; Kurth, M. J. J. Am. Chem. Soc. 1982, 104, c) Schuppan et al. Angew. Chem. Int. Ed. 2001, 40, 2063.

20. Synthesis of the cyclopentene core
a) Paquette, L. E. et al. J. Org. Chem. 1996, 61, b) Hoye, T. R.; Caruso, A. J. Dellaria, J. F.; Kurth, M. J. J. Am. Chem. Soc. 1982, 104, c) Schuppan et al. Angew. Chem. Int. Ed. 2001, 40, 2063.

21. Coupling of both partners
a) Trost, B. M.; Dong, G. Nature 2008, 456, 485.

22. Coupling of both partners
a) Trost, B. M.; Dong, G. Nature 2008, 456, 485.

23. Movassaghi’s deoxygenation reaction
a) Myers, A. G.; Movassaghi, M.; Zheng, B. J. Am. Chem. Soc. 1997, 119, 8572.

24. Intramolecular Stille reaction

25. Chemoselective reduction of tertiary amide and endmath
Barbe, G.; Charette, A. B. J. Am. Chem. Soc. 2008, 130, 18.

26. Conclusion Enantioselective and diastereoselective synthesis
of (+)-Daphnilongeranine C
 25 steps for the longest linear sequence
 38 steps total
 Key steps include :
An intramolecular [2+2] cycloaddition on a keteniminum intermediate
An intramolecular Schmidt reaction
A diastereoselective and enantioselective inverse-demand Diels-Alder
An intramolecular Stille reaction

27. Caracterization