Enantioselective synthesis of dihydropyrans. Catalysis of hetero Diels - Alder reactions by bis(oxazoline) copper(II) complexes

Journal of the American Chemical Society

Volumn 122, Issue 8, 2000, Pages 1635-1649

  Evans, David A ^a   Johnson, Jeffrey S ^a   Olhava, Edward J ^a  

^a HARVARD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

COPPER COMPLEX; PYRAN DERIVATIVE;

ARTICLE; CATALYSIS; CHEMICAL INTERACTION; CHEMICAL REACTION; CHEMICAL STRUCTURE; ENANTIOMER; REACTION ANALYSIS; SYNTHESIS;

EID: 0034006954     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja992175i     Document Type: Article

References (136)

1. National Science Foundation Predoctoral Fellow.
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4. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
5. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
6. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
7. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
8. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
9. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
10. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
11. Representative examples: (a) Monensin: Agtarap, A.; Chamberlin, J. W.; Pinkerton, M.; Steinrauf, L. J. Am. Chem. Soc. 1967, 89, 5737. (b) X-537A (Lasalocid A): Westley, J. W.; Evans, R. H.; Williams, T.; Stempel, A. Chem. Commun. 1970, 71. (c) Bryostatin I.; Pettit, G. R.; Herald, C. L.; Doubek, D. L.; Herald, D. L. J. Am. Chem. Soc. 1982, 104, 6846. (d) Miyakolide: Higa, T.; Tanaka, J.; Komesu, M.; Gravalos, D. C.; Puentes, J. L. F.; Bernardinelli, G.; Jefford, C. W. J. Am. Chem. Soc. 1992, 114, 7587. (e) Zincophorin: Brooks, H. A.; Gardner, D.; Poyser, J. P.; King, T. K. J. Antibiot. 1984, 37, 1501. (f) Altohyrtin: Kobayashi, M.; Aoki, S.; Kitigawa, I. Tetrahedron Lett. 1994, 35, 1243. (g) Phorboxazole: Searle, P. A.; Molinski, T. F. J. Am. Chem. Soc. 1995, 117, 8126. (h) Palytoxin: Cha, J. K.; Christ, W. J.; Finan, J. M.; Fujioka, H.; Kishi, Y.; Klein, L. L.; Ko, S. S.; Leder, J.; McWhorter, W. W.; Pfaff, K.-P.; Yonaga, M.; Uemura, D.; Hirata, Y. J. Am. Chem. Soc. 1982, 104, 7369.
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21. For other examples of auxiliary-controlled intermolecular inverse electron demand hetero Diels-Alder reactions, see: (a) Dondoni, A.; Kniezo, L.; Martinkova, M.; Imrich, J. Chem. Eur. J. 1997, 3, 424. (b) Degaudenzi, L.; Apparao, S.; Schmidt, R. R. Tetrahedron 1990, 46, 277. (c) Snider, B. B.; Zhang, Q. J. Org. Chem. 1991, 56, 4908. (d) Sato, M.; Sunami, S.; Kaneko, C.; Satoh, S. I.; Furuya, T. Tetrahedron: Asymmetry 1994, 5, 1665 and references therein. (e) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc., Chem. Commun. 1988, 514. (f) Hayes, P.; Dujardin, G.; Maignan, C. Tetrahedron Lett. 1996, 37, 3687. (g) Wallace, T. W.; Wardell, I.; Li, K. D.; Challand, S. R. J. Chem. Soc., Chem. Commun. 1991, 1707. (h) Haagzeino, B.; Schmidt, R. R. Liebigs Ann. Chem. 1990, 1197.
22. For other examples of auxiliary-controlled intermolecular inverse electron demand hetero Diels-Alder reactions, see: (a) Dondoni, A.; Kniezo, L.; Martinkova, M.; Imrich, J. Chem. Eur. J. 1997, 3, 424. (b) Degaudenzi, L.; Apparao, S.; Schmidt, R. R. Tetrahedron 1990, 46, 277. (c) Snider, B. B.; Zhang, Q. J. Org. Chem. 1991, 56, 4908. (d) Sato, M.; Sunami, S.; Kaneko, C.; Satoh, S. I.; Furuya, T. Tetrahedron: Asymmetry 1994, 5, 1665 and references therein. (e) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc., Chem. Commun. 1988, 514. (f) Hayes, P.; Dujardin, G.; Maignan, C. Tetrahedron Lett. 1996, 37, 3687. (g) Wallace, T. W.; Wardell, I.; Li, K. D.; Challand, S. R. J. Chem. Soc., Chem. Commun. 1991, 1707. (h) Haagzeino, B.; Schmidt, R. R. Liebigs Ann. Chem. 1990, 1197.
23. For other examples of auxiliary-controlled intermolecular inverse electron demand hetero Diels-Alder reactions, see: (a) Dondoni, A.; Kniezo, L.; Martinkova, M.; Imrich, J. Chem. Eur. J. 1997, 3, 424. (b) Degaudenzi, L.; Apparao, S.; Schmidt, R. R. Tetrahedron 1990, 46, 277. (c) Snider, B. B.; Zhang, Q. J. Org. Chem. 1991, 56, 4908. (d) Sato, M.; Sunami, S.; Kaneko, C.; Satoh, S. I.; Furuya, T. Tetrahedron: Asymmetry 1994, 5, 1665 and references therein. (e) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc., Chem. Commun. 1988, 514. (f) Hayes, P.; Dujardin, G.; Maignan, C. Tetrahedron Lett. 1996, 37, 3687. (g) Wallace, T. W.; Wardell, I.; Li, K. D.; Challand, S. R. J. Chem. Soc., Chem. Commun. 1991, 1707. (h) Haagzeino, B.; Schmidt, R. R. Liebigs Ann. Chem. 1990, 1197.
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25. For other examples of auxiliary-controlled intermolecular inverse electron demand hetero Diels-Alder reactions, see: (a) Dondoni, A.; Kniezo, L.; Martinkova, M.; Imrich, J. Chem. Eur. J. 1997, 3, 424. (b) Degaudenzi, L.; Apparao, S.; Schmidt, R. R. Tetrahedron 1990, 46, 277. (c) Snider, B. B.; Zhang, Q. J. Org. Chem. 1991, 56, 4908. (d) Sato, M.; Sunami, S.; Kaneko, C.; Satoh, S. I.; Furuya, T. Tetrahedron: Asymmetry 1994, 5, 1665 and references therein. (e) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc., Chem. Commun. 1988, 514. (f) Hayes, P.; Dujardin, G.; Maignan, C. Tetrahedron Lett. 1996, 37, 3687. (g) Wallace, T. W.; Wardell, I.; Li, K. D.; Challand, S. R. J. Chem. Soc., Chem. Commun. 1991, 1707. (h) Haagzeino, B.; Schmidt, R. R. Liebigs Ann. Chem. 1990, 1197.
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27. For other examples of auxiliary-controlled intermolecular inverse electron demand hetero Diels-Alder reactions, see: (a) Dondoni, A.; Kniezo, L.; Martinkova, M.; Imrich, J. Chem. Eur. J. 1997, 3, 424. (b) Degaudenzi, L.; Apparao, S.; Schmidt, R. R. Tetrahedron 1990, 46, 277. (c) Snider, B. B.; Zhang, Q. J. Org. Chem. 1991, 56, 4908. (d) Sato, M.; Sunami, S.; Kaneko, C.; Satoh, S. I.; Furuya, T. Tetrahedron: Asymmetry 1994, 5, 1665 and references therein. (e) Lopez, J. C.; Lameignere, E.; Lukacs, G. J. Chem. Soc., Chem. Commun. 1988, 514. (f) Hayes, P.; Dujardin, G.; Maignan, C. Tetrahedron Lett. 1996, 37, 3687. (g) Wallace, T. W.; Wardell, I.; Li, K. D.; Challand, S. R. J. Chem. Soc., Chem. Commun. 1991, 1707. (h) Haagzeino, B.; Schmidt, R. R. Liebigs Ann. Chem. 1990, 1197.
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42. A portion of this work has been previously communicated: (b) Evans, D. A.; Johnson, J. S. J. Am. Chem. Soc. 1998, 120, 4895. (b) Evans, D. A.; Olhava, E. J.; Johnson, J. S.; Janey, J. M. Angew. Chem., Int. Ed. Engl. 1998, 37, 3372. (c) Evans, D. A.; Johnson, J. S.; Burgey, C. S.; Campos, K. R. Tetrahedron Lett. 1999, 40, 2879.
43. A portion of this work has been previously communicated: (b) Evans, D. A.; Johnson, J. S. J. Am. Chem. Soc. 1998, 120, 4895. (b) Evans, D. A.; Olhava, E. J.; Johnson, J. S.; Janey, J. M. Angew. Chem., Int. Ed. Engl. 1998, 37, 3372. (c) Evans, D. A.; Johnson, J. S.; Burgey, C. S.; Campos, K. R. Tetrahedron Lett. 1999, 40, 2879.
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48. Parikh, J. R.; Doering, W. v. E. J. Am. Chem. Soc. 1967, 89, 5505.
49. Cationic copper(II) complexes were prepared as described previously. See: (a) Reference 9b. (b) Evans, D. A.; Peterson, G. S.; Johnson, J. S.; Barnes, D. M.; Campos, K. R.; Woerpel, K. A. J. Org. Chem. 1998, 63, 4541.
50. Cationic copper(II) complexes were prepared as described previously. See: (a) Reference 9b. (b) Evans, D. A.; Peterson, G. S.; Johnson, J. S.; Barnes, D. M.; Campos, K. R.; Woerpel, K. A. J. Org. Chem. 1998, 63, 4541.
51. 4OH sequesters the Cu-(II) and allows for recovery of the ligand. Assays of diastereomeric and enantiomeric excess were performed prior to flash chromatography.
52. Evans, D. A.; Murry, J. A.; von Matt, P.; Norcross, R. D.; Miller, S. J. Angew. Chem., Int. Ed. Engl. 1995, 34, 798.
53. By way of comparison, the reactivity of ethyl vinyl ether is intermediate to dihydropyran and dihydrofuran. Since these reactions may reasonably be assumed to proceed through a concerted, but asynchronous transition state (vide infra), a correlation between heterodienophile reactivity and enol ether nucleophilicity might be expected. The observed trend betweeen dihydrofuran and dihydropyran is consistent with the Mayr nucleophilicity scale, but ethyl vinyl ether was reported to be less nucleophilic than dihydropyran: Mayr, H.; Patz, M. Angew. Chem., Int. Ed. Engl. 1994, 33, 938.
54. The cycloadduct 14/15 and Michael adduct 16 do not interconvert upon independent resubjection to catalyst 2a.
55. Afarinkia, K.; Echenique, J.; Nyburg, S. C. Tetrahedron Lett. 1997, 38, 1663.
56. (a) Enders, D.; Papadopoulos, K. Tetrahedron Lett. 1983, 24, 4967.
57. (b) Shi, Y.; Wulff, W. D.; Yap, G. P. A.; Rheingold, A. L. Chem. Commun. 1996, 2601.
58. In this case, the diastereoisomeric products were separated by preparative HPLC. Dihydropyran 14 (R = TBS, 96% ee) was subjected to acidic MeOH.; the enantiomeric excess of the product keto ester 17 was also 96%.
59. Among those tried: 2-methoxypropene (1a, dr 4.5:1, 72 and 37% ee; 2b, dr 6.9:1, -57 and -38% ee), 2-trimethylsiloxypropene (2a, dr 1.7: 1, 43% ee), 1-cyclohexyl-1-trimethylsiloxyethylene (low conversion), α-methoxy styrene (2a, dr 2.4:1, 86 and 72% ee; 2b, dr 2.4:1, 36 and 49% ee). For these enol ethers, only the dihydropyran product was obtained.
60. Instead of reporting that this was the first enantioselective example of cyclopentadiene behaving as a dieneophile with an α,β-unsaturated carbonyl, our initial communication stated only that this was the first example. We thank Prof. S. Hanessian for alerting us to this error and calling to our attention this example: (a) Weichert, A.; Hoffmann, H. M. R. J. Org. Chem. 1991, 4098. In that case the normal Diels-Alder adduct was preferred (5:1). In our case, we note that when the reaction is conducted thermally (neat), the normal [4+2] pathway is preferred (2:1). To our knowledge, the first examples of cyclopentadiene acting as a dieneophile in hetero Diels-Alder reactions with α,β-unsaturated carbonyls were reported in 1982: (b) Ismail, Z. M.; Hoffmann, H. M. R. Angew. Chem., Int. Ed. Engl. 1982, 21, 859. (c) Dvorák, D.; Arnold, Z. Tetrahedron Lett. 1982, 23, 4401.
61. Instead of reporting that this was the first enantioselective example of cyclopentadiene behaving as a dieneophile with an α,β-unsaturated carbonyl, our initial communication stated only that this was the first example. We thank Prof. S. Hanessian for alerting us to this error and calling to our attention this example: (a) Weichert, A.; Hoffmann, H. M. R. J. Org. Chem. 1991, 4098. In that case the normal Diels-Alder adduct was preferred (5:1). In our case, we note that when the reaction is conducted thermally (neat), the normal [4+2] pathway is preferred (2:1). To our knowledge, the first examples of cyclopentadiene acting as a dieneophile in hetero Diels-Alder reactions with α,β-unsaturated carbonyls were reported in 1982: (b) Ismail, Z. M.; Hoffmann, H. M. R. Angew. Chem., Int. Ed. Engl. 1982, 21, 859. (c) Dvorák, D.; Arnold, Z. Tetrahedron Lett. 1982, 23, 4401.
62. Instead of reporting that this was the first enantioselective example of cyclopentadiene behaving as a dieneophile with an α,β-unsaturated carbonyl, our initial communication stated only that this was the first example. We thank Prof. S. Hanessian for alerting us to this error and calling to our attention this example: (a) Weichert, A.; Hoffmann, H. M. R. J. Org. Chem. 1991, 4098. In that case the normal Diels-Alder adduct was preferred (5:1). In our case, we note that when the reaction is conducted thermally (neat), the normal [4+2] pathway is preferred (2:1). To our knowledge, the first examples of cyclopentadiene acting as a dieneophile in hetero Diels-Alder reactions with α,β-unsaturated carbonyls were reported in 1982: (b) Ismail, Z. M.; Hoffmann, H. M. R. Angew. Chem., Int. Ed. Engl. 1982, 21, 859. (c) Dvorák, D.; Arnold, Z. Tetrahedron Lett. 1982, 23, 4401.
63. The absolute configuration of 19 was established through chemical correlation to the corresponding carboxylic acid of known absolute configuration: (a) Berson, J. A.; Bergman, R. G.; Hammons, J. H.; McRowe, A. W. J. Am. Chem. Soc. 1967, 89, 2581. (b) Berson, J. A.; Hammons, J. H.; McRowe, A. W.; Bergman, R. G.; Remanick, A.; Houston, D. J. Am. Chem. Soc. 1967, 89, 2590. (matrix presented)
64. The absolute configuration of 19 was established through chemical correlation to the corresponding carboxylic acid of known absolute configuration: (a) Berson, J. A.; Bergman, R. G.; Hammons, J. H.; McRowe, A. W. J. Am. Chem. Soc. 1967, 89, 2581. (b) Berson, J. A.; Hammons, J. H.; McRowe, A. W.; Bergman, R. G.; Remanick, A.; Houston, D. J. Am. Chem. Soc. 1967, 89, 2590. (matrix presented)
65. Evans, D. A.; Miller, S. J.; Lectka, T.; von Matt, P. J. Am. Chem. Soc. 1999, 121, 7559-7573.
66. For approaches to the synthesis of quaternary carbon stereocenters, see: (a) Fuji, K. Chem. Rev. 1993, 93, 2037. (b) Corey, E. J.; Guzman- Perez, A. Angew. Chem., Int. Ed. Engl. 1998, 37, 388.
67. For approaches to the synthesis of quaternary carbon stereocenters, see: (a) Fuji, K. Chem. Rev. 1993, 93, 2037. (b) Corey, E. J.; Guzman-Perez, A. Angew. Chem., Int. Ed. Engl. 1998, 37, 388.
68. For a relevant example, see: (a) Evans, D. A.; Chapman, K. T.; Bisaha, J. J. Am. Chem. Soc. 1988, 110, 1238. For an example of a catalytic asymmetric reaction under Curtin-Hammett control, see: (b) Halpern, J. Science 1982, 217, 401.
69. For a relevant example, see: (a) Evans, D. A.; Chapman, K. T.; Bisaha, J. J. Am. Chem. Soc. 1988, 110, 1238. For an example of a catalytic asymmetric reaction under Curtin-Hammett control, see: (b) Halpern, J. Science 1982, 217, 401.
70. Alternatively, the major diastereoisomer could be formed through an exo selective cycloaddition through the intermediacy of complex 23. Since the endo transition state is favored for every catalyzed reaction studied with ethyl vinyl ether, we do not favor this analysis. In theory, employing a group larger than ethyl should further amplify the proposed Curtin-Hammett effect; in practice, the β-methyl-β-isopropyl substrate is unreactive. No reaction was observed with 6f using catalyst 2a.
71. Sugimura, H.; Yoshida, K. Bull. Chem. Soc. Jpn. 1992, 65, 3209.
72. Tietze, L. F.; Meier, H.; Voss, E. Synthesis 1988, 274.
73. Sibi, M. P.; Marvin, M.; Sharma, R. J. Org. Chem. 1995, 60, 5016.
74. (a) Reference 9b.
75. (b) Barnes, D. M. Ph.D. Thesis, Harvard University, 1997.
76. For other uses of aquo complexes in catalytic asymmetric reactions, see: (c) Kanemasa, S.; Oderaotoshi, Y.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Org. Chem. 1997, 62, 6454-6455. (d) Kanemasa, S.; Oderaotoshi, Y.; Sakaguchi, S.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Am. Chem. Soc. 1998, 120, 3074-3088. (e) Ghosh, A. K.; Cho, H.; Cappiello, J. Tetrahedron: Asymmetry 1998, 9, 3687-3691.
77. For other uses of aquo complexes in catalytic asymmetric reactions, see: (c) Kanemasa, S.; Oderaotoshi, Y.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Org. Chem. 1997, 62, 6454-6455. (d) Kanemasa, S.; Oderaotoshi, Y.; Sakaguchi, S.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Am. Chem. Soc. 1998, 120, 3074-3088. (e) Ghosh, A. K.; Cho, H.; Cappiello, J. Tetrahedron: Asymmetry 1998, 9, 3687-3691.
78. For other uses of aquo complexes in catalytic asymmetric reactions, see: (c) Kanemasa, S.; Oderaotoshi, Y.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Org. Chem. 1997, 62, 6454-6455. (d) Kanemasa, S.; Oderaotoshi, Y.; Sakaguchi, S.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Am. Chem. Soc. 1998, 120, 3074-3088. (e) Ghosh, A. K.; Cho, H.; Cappiello, J. Tetrahedron: Asymmetry 1998, 9, 3687-3691.
79. The reaction of E-ethyl-5-methyl-2-oxo-3-hexenoate (24c) and ethyl vinyl ether was conducted with catalysts (2 mol %) prepared three different ways: (A) 27a was stirred for 1 h in THF and the reaction was conducted as normal; (B) 27a was stirred in the presence of 3 Å molecular sieves for 1 h in THF, after which time the mixture was filtered through an oven-dried 0.2 μm filter into an oven-dried flask. The reaction was conducted as normal; (C) 27a was stirred in the presence of 3 Å molecular sieves for 1 h in THF and the reaction was conducted as normal. Approximate half-lives for the reactions (0 °C): A, ≈20 h; B, ≈5 h; and C, <5 min.
80. The reactions were conducted at 0 °C for the sake of simplicity. The higher temperature should also accentuate any differences in enantioselectivity.
81. Reaction of the phenyl-substituted unsaturated keto ester in THF to give 26b: -40 °C, >99% ee; -20 °C, 98% ee; 0 °C, 97% ee; and 25 °C, 94% ee.
82. The authors thank Mr. Jacob M. Janey for performing one of these reactions (30a).
83. (a) Sibi, M. P. Org. Prep. Proc. Int. 1993, 25, 15-40.
84. (b) Mentzel, M.; Hoffmann, H. M. R. J. Prakt. Chem. 1997, 339, 517-524.
85. For an excellent example, see: Hansen, K. F.; Leighton, J. L.; Jacobsen, E. N. J. Am. Chem. Soc. 1996, 118, 10924.
86. 2, the ee is 87%.
87. If the reaction was stopped prior to completion, complete incorporation of MeOH was observed at the anomeric carbon of the dihydropyran and the equilibrium cis:trans ratio was 1:3.
88. R = Me (32a) and Ph (32b): (a) Irwin, A. J.; Jones, J. B. J. Am. Chem. Soc. 1977, 99, R = i-Pr: (b) Paquette, L. A.; Dahnke, K.; Doyon, J.; He, W.; Wyant, K.; Friedrich, D. J. Org. Chem. 1991, 56, 6199.
89. R = Me (32a) and Ph (32b): (a) Irwin, A. J.; Jones, J. B. J. Am. Chem. Soc. 1977, 99, R = i-Pr: (b) Paquette, L. A.; Dahnke, K.; Doyon, J.; He, W.; Wyant, K.; Friedrich, D. J. Org. Chem. 1991, 56, 6199.
90. 3, EtOH) at the anomeric carbon for 10, 12-endo, and 12-exo generated compound 7a as a cis/trans mixture. Comparison of retention times by GC and chiral HPLC (with co-injection of authentic samples) allowed stereochemical assignment. The correlations demonstrate that both heterodienophiles approach 6a from the same enantioface in the endo transition state. The configuration at the methyl-bearing stereocenter is opposite for the exo product derived from tert-butyl vinyl ether (12-exo). For further details, see the Supporting Information.
91. (a) Shing, T. K. M.; Tai, V. M. F.; Tan, E. K. W. Angew. Chem., Int. Ed. Engl. 1994, 33, 2312.
92. (b) Shing, T. K. M.; Tam, E. K. W.; Tai, V. W. F.; Chung, I. H. F.; Jiang, Q. Chem. Eur. J. 1996, 2, 50.
93. See the Supporting Information. The authors thank Mr. Kevin R. Campos for solving this crystal structure.
94. 40b: (a) Helmchen, G.; Nill, G. Angew. Chem., Int. Ed. Engl. 1979, 18, 66, 40c: (b) King, C.-H. R.; Poulter, C. D. J. Am. Chem. Soc. 1982, 104, 1413.
95. 40b: (a) Helmchen, G.; Nill, G. Angew. Chem., Int. Ed. Engl. 1979, 18, 66, 40c: (b) King, C.-H. R.; Poulter, C. D. J. Am. Chem. Soc. 1982, 104, 1413.
96. Desimoni, G.; Bamba, A.; Monticelli, M.; Nicola, M.; Tacconi, G. J. Am. Chem. Soc. 1976, 98, 2947.
97. For a summary, see: Boger, D. I. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 5, pp 451-512.
98. Liu, J.; Niwayama, S.; You, Y.; Houk, K. N. J. Org. Chem. 1998, 63, 1064.
99. X-ray crystallography: (a) Reference 19b. (b) Evans, D. A.; Rovis, T.; Kozlowski, M. C.; Tedrow, J. T. J. Am. Chem. Soc. 1999, 121, 1994. Double stereodifferentiating experiments: (c) Evans, D. A.; Miller, S. J.; Lectka, T. J. Am. Chem. Soc. 1993, 115, 6460. PM3 and EPR experiments: (d) Reference 9.
100. X-ray crystallography: (a) Reference 19b. (b) Evans, D. A.; Rovis, T.; Kozlowski, M. C.; Tedrow, J. T. J. Am. Chem. Soc. 1999, 121, 1994. Double stereodifferentiating experiments: (c) Evans, D. A.; Miller, S. J.; Lectka, T. J. Am. Chem. Soc. 1993, 115, 6460. PM3 and EPR experiments: (d) Reference 9.
101. X-ray crystallography: (a) Reference 19b. (b) Evans, D. A.; Rovis, T.; Kozlowski, M. C.; Tedrow, J. T. J. Am. Chem. Soc. 1999, 121, 1994. Double stereodifferentiating experiments: (c) Evans, D. A.; Miller, S. J.; Lectka, T. J. Am. Chem. Soc. 1993, 115, 6460. PM3 and EPR experiments: (d) Reference 9.
102. X-ray crystallography: (a) Reference 19b. (b) Evans, D. A.; Rovis, T.; Kozlowski, M. C.; Tedrow, J. T. J. Am. Chem. Soc. 1999, 121, 1994. Double stereodifferentiating experiments: (c) Evans, D. A.; Miller, S. J.; Lectka, T. J. Am. Chem. Soc. 1993, 115, 6460. PM3 and EPR experiments: (d) Reference 9.
103. Geometry optimizations were performed at the PM3(tm) level using the Spartan Semiempirical Program 5.0 (Wavefunction Inc., Irvine, CA 92612) on a Silicon Graphics Impact 10000 (195 MHz, 128 M RAM) running IRIX 6.2. Calculations were performed without counterions or solvent using these parameters: optcycle = 5000, maxcycle = 10000, charge = 2, multiplicity = 2. Calculations converged (energy difference between cycles <0.0005 kcal/mol) in ≤4 h CPU time.
104. (a) Johannsen, M.; Jørgensen, K. A. J. Org. Chem. 1995, 60, 5757.
105. (b) Johannsen, M.; Jørgensen, K. A. Tetrahedron 1996, 52, 7321.
106. (c) Johannsen, M.; Yao, S.; Jørgensen, K. A. Chem. Commun. 1997, 2169.
107. (d) Johannsen, M.; Yao, S.; Graven, A.; Jørgensen, K. A. Pure Appl. Chem. 1998, 70, 1117.
108. (e) Yao, S. L.; Johannsen, M.; Audrain, H.; Hazell, R. G.; Jørgensen, K. A. J. Am. Chem. Soc. 1998, 120, 8599.
109. (f) Reference 11.
110. Evans, D. A.; Burgey, C. S.; Paras, N. A.; Vojkovsky, T.; Tregay, S. W. J. Am. Chem. Soc. 1998, 120, 5824.
111. Other examples of an enantioselectivity turnover from t-Bu to Ph bis(oxazoline): (a) Ghosh, A. K.; Mathivanan, P.; Cappiello, J.; Krishnan, K. Tetrahedron: Asymmetry 1996, 7, 2165. (b) Sibi, M. P.; Ji, J.; Wu, J. H.; Guertler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200-9201. (c) Yao, S.; Johannsen, M.; Jørgensen, K. A. J. Chem. Soc., Perkin Trans. 1 1997, 2345.
112. Other examples of an enantioselectivity turnover from t-Bu to Ph bis(oxazoline): (a) Ghosh, A. K.; Mathivanan, P.; Cappiello, J.; Krishnan, K. Tetrahedron: Asymmetry 1996, 7, 2165. (b) Sibi, M. P.; Ji, J.; Wu, J. H.; Guertler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200-9201. (c) Yao, S.; Johannsen, M.; Jørgensen, K. A. J. Chem. Soc., Perkin Trans. 1 1997, 2345.
113. Other examples of an enantioselectivity turnover from t-Bu to Ph bis(oxazoline): (a) Ghosh, A. K.; Mathivanan, P.; Cappiello, J.; Krishnan, K. Tetrahedron: Asymmetry 1996, 7, 2165. (b) Sibi, M. P.; Ji, J.; Wu, J. H.; Guertler, S.; Porter, N. A. J. Am. Chem. Soc. 1996, 118, 9200-9201. (c) Yao, S.; Johannsen, M.; Jørgensen, K. A. J. Chem. Soc., Perkin Trans. 1 1997, 2345.
114. The authors thank David M. Barnes (41a) and Dr. Christopher S. Burgey (41b,c) for obtaining these crystals and Mr. Kevin R. Campos for solving the structures.
115. Hathaway, B. J.; Billing, D. E. Coord. Chem. Rev. 1970, 5, 143.
116. 2O) was 3.32 Å; the distance from the water oxygen to the phenyl centroid is ca. 3.9 Å for 41b.
117. 6 counterions) successfully reproduced the direction of distortion, but not the magnitude (ca. 30°).
118. For experimental verification of this effect in Diels-Alder reactions of Cu(II) vs Zn(II) Lewis acids, see: Evans, D. A.; Kozlowski, M. C.; Tedrow, J. S. Tetrahedron Lett. 1996, 37, 7481.
119. The above discussion relies on reactions proceeding through a concerted, asynchronous transition state, but at this time it is not possible to exclude a two-step mechanism. Tietze and Evans have both provided experimental evidence for concerted cycloadditions: (a) Tietze, L. F.; Bratz, M.; Machinek, R.; Kiedrowski, G. v. J. Org. Chem. 1987, 52, 1638. (b) Reference 11a. Even if the reaction occurs in two steps, the uniformally high diastereoselectivities suggest a highly ordered transition state.
120. The above discussion relies on reactions proceeding through a concerted, asynchronous transition state, but at this time it is not possible to exclude a two-step mechanism. Tietze and Evans have both provided experimental evidence for concerted cycloadditions: (a) Tietze, L. F.; Bratz, M.; Machinek, R.; Kiedrowski, G. v. J. Org. Chem. 1987, 52, 1638. (b) Reference 11a. Even if the reaction occurs in two steps, the uniformally high diastereoselectivities suggest a highly ordered transition state.
121. Girard, C.; Kagan, H. B. Angew. Chem., Int. Ed. Engl. 1998, 37, 2923.
122. Barnes, D. M. Ph.D. Thesis, Harvard University, 1997.
123. (a) Evans, D. A.; Lectka, T.; Miller, S. J. Tetrahedron Lett. 1993, 34, 7027.
124. (b) Kanemasa, S.; Oderaotoshi, Y.; Sakaguchi, S.; Yamamoto, H.; Tanaka, J.; Wada, E.; Curran, D. P. J. Am. Chem. Soc. 1998, 120, 3074.
125. (c) Evans, D. A.; Kozlowski, M. C.; Murry, J. A.; Burgey, C. S.; Campos, K. R.; Connell, B. T.; Staples, R. J. J. Am. Chem. Soc. 1999, 121, 669.
126. Palucki, M.; Finney, N. S.; Pospisil, P. J.; Guler, M. L.; Ishida, T.; Jacobsen, E. N. J. Am. Chem. Soc. 1998, 120, 948.
127. The ligands were synthesized according to the method of ref 19b. For synthessis of the amino alcohols, see: (a) Chang, H. T.; Sharpless, K. B. Tetrahedron Lett. 1996, 37, 3219. (b) Kawasaki, K.; Katsuki, T. Tetrahedron 1997, 53, 6337.
128. The ligands were synthesized according to the method of ref 19b. For synthessis of the amino alcohols, see: (a) Chang, H. T.; Sharpless, K. B. Tetrahedron Lett. 1996, 37, 3219. (b) Kawasaki, K.; Katsuki, T. Tetrahedron 1997, 53, 6337.
129. (a) Oppolzer, W.; Kurth, M.; Reichlin, D.; Chapuis, C.; Mohnhaupt, M.; Moffatt, F. Helv. Chim. Acta 1981, 64, 2802.
130. (b) Evans, D. A.; Chapman, K. T.; Hung, D. T.; Kawaguchi, A. T. Angew. Chem., Int. Ed. Engl. 1987, 26, 1184.
131. (c) Quan, R. W.; Li, Z.; Jacobsen, E. N. J. Am. Chem. Soc. 1996, 118, 8156.
132. Buschmann, H.; Scharf, H.-D.; Hoffmann, H.; Esser, P. Angew. Chem., Int. Ed. Engl. 1991, 30, 477.
133. Davies, I. W.; Deeth, R. J.; Larsen, R. D.; Reider, P. J. Tetrahedron Lett. 1999, 40, 1233.
134. For an excellent discussion on cation π interactions, see: Dougherty, D. A. Science 1996, 271, 163.
135. Since experiments suggest that reactions with α-trialkylsiloxystyrene are not concerted, antiperiplanar approach of the nucleophile should also be considered; however, reactions with E and Z propionate silyl enol ethers and ketene acetals in the study of the Mukaiyama Michael reaction have provided some evidence that these additions proceed via a synclinal transition state. Evans, D. A.; Willis, M. C.; Johnston, J. N. Org. Lett. 1999, 1, 865.
136. Evans, D. A.; Johnson, D. S. Org. Lett. 1999, 1, 595.