2(3H)-and 2(5H)-furanones. VII. Chirality transfer on the tetronic acid templates

Heterocycles

Volumn 51, Issue 6, 1999, Pages 1321-1343

  Momose, Takefumi ^a   Toyooka, Naoki ^a   Nishio, Morihiro ^a   Shinoda, Hiroyuki ^a   Fujii, Hiromi ^b   Yanagino, Hironobu ^b  

^a UNIVERSITY OF TOYAMA   (Japan)

^b KINKI UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

3 METHYL 3 (3 OXOBUTYL) 5 (2 PROPYL) 2,4 FURANDIONE; 3 [2 (1,3 DIOXOLAN 2 YL)ETHYL] 3 METHYL 5 (2 PROPYL) 2,4 FURANDIONE; AMINE; CASSIOL; FURANONE DERIVATIVE; O METHYLJOUBERTIAMINE; UNCLASSIFIED DRUG;

ALKYLATION; ARTICLE; CHEMICAL REACTION; CHIRALITY; DIASTEREOISOMER; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0033150197     PISSN: 03855414     EISSN: None     Source Type: Journal    
DOI: 10.3987/com-99-8494     Document Type: Article

References (40)

1. The previous paper entitled "Di-π-methane rearrangement of the α-substituted 4-benzylfuran-2(5H)-one system" [O. Muraoka, G. Tanabe, M. Higashiura, T. Minematsu, and T. Momose, J. Chem. Soc. Perkin Trans., 1, 1995, 1437] constitutes Part VI of this series.
2. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
3. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
4. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
5. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
6. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
7. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
8. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
9. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
10. D. G. Schmidt, P. D. Seemuth, and H. Zimmer, J. Org. Chem., 1983, 48, 1914; Y. Hamada, A. Kawai, and T. Shioiri, Tetrahedron Lett., 1984, 25, 5409; Idem, Chem. Pharm. Bull., 1985, 33, 5601; T. Kametani, T. Katoh, M. Tsubuki, and T. Honda, J. Am. Chem. Soc., 1986, 108, 7055; Idem, Chem. Pharm. Bull., 1987, 35, 2334; K. Okumura, K. Okazaki, K. Takeda, and E. Yoshii, Tetrahedron Lett., 1989, 30, 2233; T. Honda, T. Hayakawa, H. Kondoh, A. Okuyama, and M. Tsubuki, Chem. Lett., 1991, 1861; T. Honda, T. Yamada, T. Hayakawa, and K. Kanai, Tetrahedron: Asymmetry, 1994, 5, 247; F. Effenberger and J. Syed, Tetrahedron: Asymmetry, 1998, 9, 817 and references cited therein.
11. T. Momose, N. Toyooka, and Y. Takeuchi, Heterocycles, 1986, 24, 1429.
12. T. Momose, N. Toyooka, T. Nishi, and Y. Takeuchi, Heterocycles, 1988, 27, 1907.
13. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
14. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
15. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
16. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
17. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
18. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
19. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
20. Selective O-alkylation of tetronic acids has been reported; see A. S. Wegnel, T. Reffstrup, and P. M. Boll, Tetrahedron, 1979, 35, 2181; S. V. Ley and D. J. Wadsworth, Tetrahedron Lett., 1989, 30, 1001; S. Gelin and P. Pallet, Synth. Commun., 1980, 10, 805; H. Zimmer, A. Amer, C. V. Pham, and D. G. Schmidt, J. Org. Chem., 1988, 53, 3368; J. S. Bajwa and R. C. Anderson, Tetrahedron Lett., 1990, 31, 6973. Selective C-alkylation of tetronic acids has been reported, see: M. Moreno-Mañas, M. Prat, J. Ribas, and A. Virgiri, Tetrahedron Lett., 1988, 29, 581. Selective C-alkylation of ascorbic acid has been reported, see: A. J. Poss and R. K. Belter, Synth. Commun., 1988, 18, 417; M. Moreno-Mañas, R. Pleixats, and M. Villarroya, J. Org. Chem., 1990, 55, 4925.
21. For preliminary accounts, see: T. Momose, N. Toyooka, H. Fujii, and H. Yanagino, Heterocycles, 1989, 29, 453.
22. a) Isolation, see: T. Akira, S. Tanaka, and M. Tabata, Planta Medica, 1986, 440; Y. Shiraga, K. Okano, T. Akira, C. Fukaya, K. Yokoyama, S. Tanaka, H. Fukui, and M. Tabata, Tetrahedron, 1988, 44, 4703.
23. a) Isolation, see: T. Akira, S. Tanaka, and M. Tabata, Planta Medica, 1986, 440; Y. Shiraga, K. Okano, T. Akira, C. Fukaya, K. Yokoyama, S. Tanaka, H. Fukui, and M. Tabata, Tetrahedron, 1988, 44, 4703.
24. b) First chiral synthesis, see: T. Takemoto, C. Fukaya, and K. Yokoyama, Tetrahedronn Lett., 1989, 30, 723.
25. c) Other chiral syntheses, see: T. Uno, H. Watanabe, and K. Mori, Tetrahedron, 1990, 46, 5563; E. J. Corey, A. Guzman-Perez, and T.-P. Loh, J. Am. Chem. Soc., 1994, 116, 3611; B. M. Trost and Y. Li, J. Am. Chem. Soc., 1996, 118, 6625; D. F. Taber, R. P. Meagley, and D. J. Doren, J. Org. Chem., 1996, 61, 5723; O. Irie, Y. Fujiwara, H. Nemoto, and K. Shishido, Tetrahedron Lett., 1996, 37, 9229; S. Maiti, B. Achari, and A. K. Banerjee, SYNLETT, 1998, 129.
26. c) Other chiral syntheses, see: T. Uno, H. Watanabe, and K. Mori, Tetrahedron, 1990, 46, 5563; E. J. Corey, A. Guzman-Perez, and T.-P. Loh, J. Am. Chem. Soc., 1994, 116, 3611; B. M. Trost and Y. Li, J. Am. Chem. Soc., 1996, 118, 6625; D. F. Taber, R. P. Meagley, and D. J. Doren, J. Org. Chem., 1996, 61, 5723; O. Irie, Y. Fujiwara, H. Nemoto, and K. Shishido, Tetrahedron Lett., 1996, 37, 9229; S. Maiti, B. Achari, and A. K. Banerjee, SYNLETT, 1998, 129.
27. c) Other chiral syntheses, see: T. Uno, H. Watanabe, and K. Mori, Tetrahedron, 1990, 46, 5563; E. J. Corey, A. Guzman-Perez, and T.-P. Loh, J. Am. Chem. Soc., 1994, 116, 3611; B. M. Trost and Y. Li, J. Am. Chem. Soc., 1996, 118, 6625; D. F. Taber, R. P. Meagley, and D. J. Doren, J. Org. Chem., 1996, 61, 5723; O. Irie, Y. Fujiwara, H. Nemoto, and K. Shishido, Tetrahedron Lett., 1996, 37, 9229; S. Maiti, B. Achari, and A. K. Banerjee, SYNLETT, 1998, 129.
28. c) Other chiral syntheses, see: T. Uno, H. Watanabe, and K. Mori, Tetrahedron, 1990, 46, 5563; E. J. Corey, A. Guzman-Perez, and T.-P. Loh, J. Am. Chem. Soc., 1994, 116, 3611; B. M. Trost and Y. Li, J. Am. Chem. Soc., 1996, 118, 6625; D. F. Taber, R. P. Meagley, and D. J. Doren, J. Org. Chem., 1996, 61, 5723; O. Irie, Y. Fujiwara, H. Nemoto, and K. Shishido, Tetrahedron Lett., 1996, 37, 9229; S. Maiti, B. Achari, and A. K. Banerjee, SYNLETT, 1998, 129.
29. c) Other chiral syntheses, see: T. Uno, H. Watanabe, and K. Mori, Tetrahedron, 1990, 46, 5563; E. J. Corey, A. Guzman-Perez, and T.-P. Loh, J. Am. Chem. Soc., 1994, 116, 3611; B. M. Trost and Y. Li, J. Am. Chem. Soc., 1996, 118, 6625; D. F. Taber, R. P. Meagley, and D. J. Doren, J. Org. Chem., 1996, 61, 5723; O. Irie, Y. Fujiwara, H. Nemoto, and K. Shishido, Tetrahedron Lett., 1996, 37, 9229; S. Maiti, B. Achari, and A. K. Banerjee, SYNLETT, 1998, 129.
30. c) Other chiral syntheses, see: T. Uno, H. Watanabe, and K. Mori, Tetrahedron, 1990, 46, 5563; E. J. Corey, A. Guzman-Perez, and T.-P. Loh, J. Am. Chem. Soc., 1994, 116, 3611; B. M. Trost and Y. Li, J. Am. Chem. Soc., 1996, 118, 6625; D. F. Taber, R. P. Meagley, and D. J. Doren, J. Org. Chem., 1996, 61, 5723; O. Irie, Y. Fujiwara, H. Nemoto, and K. Shishido, Tetrahedron Lett., 1996, 37, 9229; S. Maiti, B. Achari, and A. K. Banerjee, SYNLETT, 1998, 129.
31. d) First chiral synthesis of (-)-cassioside, see: R. K. Boekman, Jr. and Y. Liu, J. Org. Chem., 1996, 61, 7984.
32. a) Isolation, see: J. J. Nieuwenhuis, F. Stelow, H. F. Strauss, and A. Wiechers, J. Chem. Soc., Perkin Trans. 1, 1981, 284.
33. b) First chiral synthesis, see: M. Asaoka, N. Fujii, and H. Takei, Chem. Lett., 1988, 1655.
34. c) Other chiral synthesis, see: D. F. Taber, J. F. Mack, A. L. Rheingold, and S. J. Geib, J. Org. Chem., 1989, 54, 3831.
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36. 1H NMR spectrum of the MTPA ester of the alcohol (A) derived from 4a. (matrix presented)
37. The enantiomeric excess of the C-allyl products (4a), (4b), and (4c) obtained from procedure B or Claisen rearrangement of corresponding allyl tetronates 3a-c was comfirmed by the comparison of the optical rotations with those of 4a-c obtained from procedure C (see experimental section).
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