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
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
Retrosynthetic analysis
Retrosynthetic analysis
Synthesis of the cyclohexenone core a) Funk, R.L.; Bolton, G. L. J. Org. Chem. 1987, 52, 3174. b) Evans, D. A.; Bender, S. L. Tetrahedron Lett. 1986, 27, 799.
Synthesis of the cyclohexenone core a) Funk, R.L.; Bolton, G. L. J. Org. Chem. 1987, 52, 3174. b) Evans, D. A.; Bender, S. L. Tetrahedron Lett. 1986, 27, 799.
Synthesis of the cyclohexenone core a) Funk, R.L.; Bolton, G. L. J. Org. Chem. 1987, 52, 3174. b) Evans, D. A.; Bender, S. L. Tetrahedron Lett. 1986, 27, 799.
Synthesis of the cyclohexenone core
Synthesis of the cyclohexenone core a) Kanematsu, M. et al. Synthesis 2009, 17, 2893. b) Fischer, C.; Fu, G.C. J. Am. Chem. Soc. 2005, 127, 4594. c) Rudolph, A.; Lautens, M. Angew. Chem. Int. Ed. 2009, 48, 2. d) Genicot, C.; Gobeaux, B.; Ghosez, L. Tetrahedron Lett. 1991, 32, 3827.
Synthesis of the cyclohexenone core (alternative) a) Kanematsu, M. et al. Synthesis 2009, 17, 2893. b) Fischer, C.; Fu, G.C. J. Am. Chem. Soc. 2005, 127, 4594. c) Rudolph, A.; Lautens, M. Angew. Chem. Int. Ed. 2009, 48, 2. d) Genicot, C.; Gobeaux, B.; Ghosez, L. Tetrahedron Lett. 1991, 32, 3827.
Intramolecular [2+2] on a keteniminium intermediate Genicot, C.; Gobeaux, B.; Ghosez, L. Tetrahedron Lett. 1991, 32, 3827.
Ring expansion via an intramolecular Schmidt reaction a) Martinelli, M. J.; et al. Tetrahedron Lett. 2000, 41, 3773. b) Zhen, Z. B. et al J. Org. Chem. 2008, 73, 7310 c) Zeng, Y.; Aubé, J. J. Am. Chem. Soc. 2005, 127, 15712.
Ring expansion via an intramolecular Schmidt reaction Zeng, Y.; Aubé, J. J. Am. Chem. Soc. 2005, 127, 15712.
Synthesis of the cyclopentene core a) Babler, J. H. et al. Synth. Commun. 1996, 26, 1943. b) Kvita, V. et al. Helv. Chem. Acta 1990, 73, 883.
Synthesis of the cyclopentene core a) Babler, J. H. et al. Synth. Commun. 1996, 26, 1943. b) Kvita, V. et al. Helv. Chem. Acta 1990, 73, 883. c) Marko, I. E. et al. Tetrahedron Lett. 1994, 35, 2771. d) Marko, I. E. et al Org. Lett. 2000, 2, 2123.
Radical-mediated ring fragmentation c) Marko, I. E. et al. Tetrahedron Lett. 1994, 35, 2771. d) Marko, I. E. et al Org. Lett. 2000, 2, 2123.
Radical-mediated ring fragmentation c) Marko, I. E. et al. Tetrahedron Lett. 1994, 35, 2771. d) Marko, I. E. et al Org. Lett. 2000, 2, 2123.
Synthesis of the cyclopentene core a) Kende, A. S. et al. J. Am. Chem. Soc. 1990, 112, 4070. c) Kazahawa, K. et al. Synlett 2004, 1640. d) Paquette, L. E. et al. J. Org. Chem. 1996, 61, 3268.
Synthesis of the cyclopentene core a) Paquette, L. E. et al. J. Org. Chem. 1996, 61, 3268. b) Hoye, T. R.; Caruso, A. J. Dellaria, J. F.; Kurth, M. J. J. Am. Chem. Soc. 1982, 104, 6704. c) Schuppan et al. Angew. Chem. Int. Ed. 2001, 40, 2063.
Synthesis of the cyclopentene core a) Paquette, L. E. et al. J. Org. Chem. 1996, 61, 3268. b) Hoye, T. R.; Caruso, A. J. Dellaria, J. F.; Kurth, M. J. J. Am. Chem. Soc. 1982, 104, 6704. c) Schuppan et al. Angew. Chem. Int. Ed. 2001, 40, 2063.
Coupling of both partners a) Trost, B. M.; Dong, G. Nature 2008, 456, 485.
Coupling of both partners a) Trost, B. M.; Dong, G. Nature 2008, 456, 485.
Movassaghi’s deoxygenation reaction a) Myers, A. G.; Movassaghi, M.; Zheng, B. J. Am. Chem. Soc. 1997, 119, 8572.
Intramolecular Stille reaction
Chemoselective reduction of tertiary amide and endmath Barbe, G.; Charette, A. B. J. Am. Chem. Soc. 2008, 130, 18.
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
Caracterization