Enantiodivergent syntheses of γ-substituted butenolides with tertiary and quaternary asymmetric centers

Tetrahedron Letters

Volumn 44, Issue 4, 2003, Pages 745-749

  Suzuki, Katsufumi ^a   Inomata, Kohei ^a  

^a TOHOKU PHARMACEUTICAL UNIVERSITY   (Japan)

Author keywords

Butenolides; Chiral building block; Chiral synthesis; Lactones; Nucleophilic addition

Indexed keywords

BUTENOLIDE; LACTONE; ORGANOMETALLIC COMPOUND;

ARTICLE; CHIRALITY; DIELS ALDER REACTION; ENANTIOMER; STEREOCHEMISTRY; SYNTHESIS;

EID: 0037455046     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(02)02711-9     Document Type: Article

References (44)

1. Rao Y.S. Chem. Rev. 64:1964;353-388.
2. Rao Y.S. Chem. Rev. 76:1976;625-694.
3. For examples of syntheses of γ-substituted butenolides, see the following reviews: (a) Negishi, E.; Kotora, M. Tetrahedron 1997, 53, 6707-6738; (b) Brückner, R. Chem. Commun. 2001, 141-152
4. For examples of syntheses of γ-substituted butenolides, see the following reviews: (a) Negishi, E.; Kotora, M. Tetrahedron 1997, 53, 6707-6738; (b) Brückner, R. Chem. Commun. 2001, 141-152.
5. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
6. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
7. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
8. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
9. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
10. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
11. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
12. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
13. For some examples of recent chiral syntheses of γ-substituted butenolides, see: (a) Martin, S. F.; Lopez, O. D. Tetrahedron Lett. 1999, 40, 8949-8953; (b) Nakache, P.; Ghera, E.; Hassner, A. Tetrahedron Lett. 2000, 41, 5583-5587; (c) Braun, M.; Rahematpura, J.; Bühne, C.; Paulitz, T. C. Synlett 2000, 1070-1072; (d) D'Oca, M. G. M.; Pilli, R. A.; Vencato, I. Tetrahedron Lett. 2000, 41, 9709-9712; (e) Ma, S.; Wu, S. Chem. Commun. 2001, 441-442; (f) Ma, S.; Shi, Z.; Wu, S. Tetrahedron: Asymmetry 2001, 12, 193-195; (g) Rudler, H.; Parlier, A.; Certal, V.; Frison, J.-C. Tetrahedron Lett. 2001, 42, 5235-5237; (h) Honzumi, M.; Ogasawara, K. Tetrahedron Lett. 2002, 43, 1047-1049.
14. Preliminary results of this work were presented at The 122nd Annual Meeting of the Pharmaceutical Society of Japan, Chiba, Japan, March 26-28, 2002. See abstracts vol. 2, p 39.
15. Preliminary results of this work were presented at The 122nd Annual Meeting of the Pharmaceutical Society of Japan, Chiba, Japan, March 26-28, 2002. See abstracts vol. 2, p 39.
16. 1M, undesirable dialkylated products were preferentially yielded.
17. A solvent effect similar to that of nucleophilic addition to lactone derivatives has been reported, see: Bessieres B., Morin C. Synlett. 2000;1691-1693.
18. 4) and evaporated under reduced pressure. The residue was chromatographed on silica gel (benzene/AcOEt=2/1) to give 6j (137 mg, 84%) as a colorless oil.
19. Ley S.V., Norman J., Griffith W.P., Marsden S.P. Synthesis. 1994;639-666.
20. Bloch R., Brillet C. Synlett. 1991;829-830.
21. Similar synthesis of butenolides via the retro-Diels-Alder reaction, see: Corbera, J.; Font, J.; Monsalvatje, M.; Ortuño, R. M.; Sánchez-Ferrando, F. J. Org. Chem. 1988, 53, 4393-4395. See also Refs. 13a and 16a.
22. Similar synthesis of butenolides via the retro-Diels-Alder reaction, see: Corbera, J.; Font, J.; Monsalvatje, M.; Ortuño, R. M.; Sánchez-Ferrando, F. J. Org. Chem. 1988, 53, 4393-4395. See also Refs. 13a and 16a.
23. For examples of chiral syntheses of 2a, see: (a) Bloch, R.; Gilbert, L. J. Org. Chem. 1987, 52, 4603-4605; (b) Takahata, H.; Uchida, Y.; Momose, T. J. Org. Chem. 1995, 60, 5628-5633; (c) Harcken, C.; Brückner, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 2750-2752; (d) Tsuboi, S.; Sakamoto, J.; Yamashita, H.; Sakai, T.; Utaka, M. J. Org. Chem. 1998, 63, 1102-1108.
24. For examples of chiral syntheses of 2a, see: (a) Bloch, R.; Gilbert, L. J. Org. Chem. 1987, 52, 4603-4605; (b) Takahata, H.; Uchida, Y.; Momose, T. J. Org. Chem. 1995, 60, 5628-5633; (c) Harcken, C.; Brückner, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 2750-2752; (d) Tsuboi, S.; Sakamoto, J.; Yamashita, H.; Sakai, T.; Utaka, M. J. Org. Chem. 1998, 63, 1102-1108.
25. For examples of chiral syntheses of 2a, see: (a) Bloch, R.; Gilbert, L. J. Org. Chem. 1987, 52, 4603-4605; (b) Takahata, H.; Uchida, Y.; Momose, T. J. Org. Chem. 1995, 60, 5628-5633; (c) Harcken, C.; Brückner, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 2750-2752; (d) Tsuboi, S.; Sakamoto, J.; Yamashita, H.; Sakai, T.; Utaka, M. J. Org. Chem. 1998, 63, 1102-1108.
26. For examples of chiral syntheses of 2a, see: (a) Bloch, R.; Gilbert, L. J. Org. Chem. 1987, 52, 4603-4605; (b) Takahata, H.; Uchida, Y.; Momose, T. J. Org. Chem. 1995, 60, 5628-5633; (c) Harcken, C.; Brückner, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 2750-2752; (d) Tsuboi, S.; Sakamoto, J.; Yamashita, H.; Sakai, T.; Utaka, M. J. Org. Chem. 1998, 63, 1102-1108.
27. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
28. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
29. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
30. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
31. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
32. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
33. For examples of chiral syntheses of 2b, see: (a) Camps, P.; Cardellach, J.; Corbera, J.; Font, J.; Ortuño, R. M.; Ponsatí, O. Tetrahedron 1983, 39, 395-400; (b) Chen, S-H.; Joullié, M. M. J. Org. Chem. 1984, 49, 2168-2174; (c) Cardellach, J.; Font, J.; Ortuño, R. M. Tetrahedron Lett. 1985, 26, 2815-2816; (d) Ortuño, R. M.; Alonso, D.; Font, J. Tetrahedron Lett. 1986, 27, 1079-1080; (e) Ortuño, R. M.; Alonso, D.; Cardellach, J.; Font, J. Tetrahedron 1987, 43, 2191-2198; (f) Bertus, P.; Phansavath, P.; Ratovelomanana-Vidal, V.; Genêt, J.-P.; Touati, A. R.; Homri, T.; Ben Hassine, B. Tetrahedron: Asymmetry 1999, 10, 1369-1380; (g) Tiecco, M.; Testaferri, L.; Marini, F.; Sternativo, S.; Bagnoli, L.; Santi, C.; Temperini, A. Tetrahedron: Asymmetry 2001, 12, 1493-1502. See also Ref. 13a.
34. For examples of chiral syntheses of 2c, see: (a) Bravo, P.; Carrera, P.; Resnati, G.; Ticozzi, C. Chem. Commun. 1984, 19-20; (b) Albinati, A.; Bravo, P.; Ganazzoli, F.; Resnati, G.; Viani, F. J. Chem. Soc., Perkin 1 1986, 1405-1415; See also Ref. 16b.
35. For examples of chiral syntheses of 2c, see: (a) Bravo, P.; Carrera, P.; Resnati, G.; Ticozzi, C. Chem. Commun. 1984, 19-20; (b) Albinati, A.; Bravo, P.; Ganazzoli, F.; Resnati, G.; Viani, F. J. Chem. Soc., Perkin 1 1986, 1405-1415; See also Ref. 16b.
36. For examples of chiral syntheses of 2d, see: (a) Bloch, R.; Brillet, C. Tetrahedron: Asymmetry 1991, 2, 797-800; (b) Renard, M.; Ghosez, L. A. Tetrahedron 2001, 57, 2597-2608.
37. For examples of chiral syntheses of 2d, see: (a) Bloch, R.; Brillet, C. Tetrahedron: Asymmetry 1991, 2, 797-800; (b) Renard, M.; Ghosez, L. A. Tetrahedron 2001, 57, 2597-2608.
38. For examples of chiral syntheses of 2e, see: (a) Musierowicz, S.; Wróblewski, A. E. Tetrahedron 1978, 34, 461-465; (b) Gaul, C.; Schärer, K.; Seebach, D. J. Org. Chem. 2001, 66, 3059-3037.
39. For examples of chiral syntheses of 2e, see: (a) Musierowicz, S.; Wróblewski, A. E. Tetrahedron 1978, 34, 461-465; (b) Gaul, C.; Schärer, K.; Seebach, D. J. Org. Chem. 2001, 66, 3059-3037.
40. Berkenbusch, T.; Brückner R. Tetrahedron 1998, 54, 11461-11470.
41. Harcken C., Brückner R., Rank E. Chem. Eur. J. 4:1998;2342-2352.
42. Takadoi M., Katoh T., Ishiwata A., Terashima S. Tetrahedron Lett. 40:1999;3399-3402.
43. 2 216.1150. Found: 216.1158.
44. In Ref. 4, we reported that ee values of (+)- and (-)-2a were 90-92% because of a partial racemizaton occurring under these reaction conditions. After the publication, we determined the ee of starting lactone 1. Because the lactone 1 we used in Ref. 4 existed in 90% ee, no racemization occurred through the retro-Diels-Alder reaction. In this report, lactone 1 with >98% ee, which was synthesized by the method in Ref. 6, was used as a starting material.