Syntheses of strychnine, norfluorocurarine, dehydrodesacetylretuline, and valparicine enabled by intramolecular cycloadditions of Zincke aldehydes

Journal of Organic Chemistry

Volumn 77, Issue 1, 2012, Pages 17-46

  Martin, David B C ^a   Nguyen, Lucas Q ^a   Vanderwal, Christopher D ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CYCLOREVERSION; DIELS-ALDER CYCLOADDITIONS; INTRAMOLECULAR CYCLOADDITIONS; MONOTERPENES;

ALDEHYDES; CYCLOADDITION;

ORGANIC COMPOUNDS;

ALDEHYDE DERIVATIVE; ALKALOID DERIVATIVE; DEHYDRODESACETYLRETULINE; INDOLE DERIVATIVE; NORFLUOROCURARINE; STRYCHNINE; TERPENE DERIVATIVE; TRYPTAMINE; UNCLASSIFIED DRUG; VALPARICINE; ZINCKE ALDEHYDE;

ARTICLE; CHEMICAL REACTION KINETICS; CONTROLLED STUDY; CROSS LINKING; CYCLOADDITION; CYCLOREVERSION; DIELS ALDER REACTION; DIMERIZATION; SYNTHESIS;

ALDEHYDES; CYCLIZATION; DIMERIZATION; INDOLE ALKALOIDS; MAGNETIC RESONANCE SPECTROSCOPY; MOLECULAR STRUCTURE; STRYCHNINE; TUBOCURARINE;

EID: 84855558725     PISSN: 00223263     EISSN: 15206904     Source Type: Journal    
DOI: 10.1021/jo2020246     Document Type: Article

References (160)

1. Pelletier, P. J.; Caventou, J. B. Ann. Chim. Phys. 1818, 8, 323
2. Pelletier, P. J.; Caventou, J. B. Ann. Chim. Phys. 1819, 10, 142
3. Regnault, V. Ann. 1838, 26 (17) 35
4. For a historical review of the chemistry of strychnine, see: Smith, G. F. In The Alkaloids; Manske, R. H. F., Ed.; Academic Press: New York, 1965; Vol. 8, pp 591-671.
5. For a lead reference that includes the synthesis of the Wieland-Gumlich aldehyde from strychnine, see: Anet, F. A. L.; Robinson, R. J. Chem. Soc. 1955, 2253-2262
6. For the original conversion of the Wieland-Gumlich aldehyde into strychnine, see: Anet, F. A. L.; Robinson, R. Chem. Ind. 1953, 245
7. Briggs, L. H.; Openshaw, H. T.; Robinson, R. J. Chem Soc. 1946, 903-908
8. Holmes, H. L.; Openshaw, H. T.; Robinson, R. J. Chem Soc. 1946, 910-912
9. Woodward, R. B.; Brehm, W. J. J. Am. Chem. Soc. 1948, 70, 2107-2115
10. Hofmann, A. W. Ann. 1851, 78, 253-286
11. Hofmann, A. W. Ber 1881, 14, 659-669
12. Polonovski, M.; Polonovski, M. Bull. Soc. Chim. Fr. 1927, 41, 1190-1208
13. Polonovski, M.; Polonovski, M. Bull. Soc. Chim. Belg 1930, 39, 1-39
14. von Braun, J. Ber 1900, 33, 1438
15. Emde, H. Ber. Deutsch Chem. Ges. 1909, 42, 2590
16. Bisset, N. G. In Indole and Biogenetically Related Alkaloids; Phillipson, J. D.; Zenk, M. H., Eds.; Academic Press: London, 1980; pp 27-61.
17. Kisakürek, M. V.; Leeuwenberg, A. J. M.; Hesse, M. In Alkaloids: Chemical and Biological Perspectives; Pelletier, S. W., Ed.; Wiley: New York, 1983; Vol 1, pp 211-376.
18. Woodward, R. B.; Cava, M. P.; Ollis, W. D.; Hunger, A.; Daeniker, H. U.; Schenker, K. J. Am. Chem. Soc. 1954, 76, 4749-4751
19. Magnus, P.; Giles, M.; Bonnert, R.; Kim, C. S.; McQuire, L.; Merritt, A.; Vicker, N. J. Am. Chem. Soc. 1992, 114, 4403-4405
20. Knight, S. D.; Overman, L. E.; Pairaudeau, G. J. Am. Chem. Soc. 1993, 115, 9293-9294
21. Kuehne, M. E.; Xu, F. J. Org. Chem. 1993, 58, 7490-7497
22. Rawal, V. H.; Iwasa, S. J. Org. Chem. 1994, 59, 2685-2686
23. Kuehne, M. E.; Xu, F. J. Org. Chem. 1998, 63, 9427-9433
24. Solé, D.; Bonjoch, J.; García-Rubio, S.; Peidró, E.; Bosch, J. Angew. Chem., Int. Ed. 1999, 38, 395-397
25. Ito, M.; Clark, C. W.; Mortimore, M.; Goh, J. B.; Martin, S. F. J. Am. Chem. Soc. 2001, 123, 8003-8010
26. Eichberg, M. J.; Dorta, R. L.; Lamottke, K.; Vollhardt, K. P. C. Org. Lett. 2000, 2, 2479-2481
27. Nakanishi, M.; Mori, M. Angew. Chem., Int. Ed. 2002, 41, 1934-1936
28. Bodwell, G. J.; Li, J. Angew. Chem., Int. Ed. 2002, 41, 3261-3262
29. Ohshima, T.; Xu, Y.; Takita, R.; Shimuzu, S.; Zhong, D.; Shibasaki, M. J. Am. Chem. Soc. 2002, 124, 14546-14547
30. Kaburagi, Y.; Tokuyama, H.; Fukuyama, T. J. Am. Chem. Soc. 2004, 126, 10246-10247
31. Zhang, H.; Boonsombat, J.; Padwa, A. Org. Lett. 2007, 9, 279-282
32. Sirasani, G.; Paul, T.; Dougherty, W., Jr.; Kassel, S.; Andrade, R. B. J. Org. Chem. 2010, 75, 3529-3532
33. Beemelmanns, C.; Reissig, H.-U. Angew. Chem., Int. Ed. 2010, 49, 8021-8025
34. Martin, D. B. C.; Vanderwal, C. D. Chem. Sci. 2011, 2, 649-651
35. Jones, S. B.; Simmons, B.; Mastracchio, A.; MacMillan, D. W. C. Nature 2011, 475, 185-188
36. Bonjoch, J.; Solé, D. Chem. Rev. 2000, 100, 3455-3482
37. Mori, M. Heterocycles 2010, 81, 259-292
38. Woodward, R. B. Nature 1948, 168, 155-156
39. Le Men, J.; Taylor, W. I. Experientia 1965, 21, 508-510
40. Kearney, A. M.; Vanderwal, C. D. Angew. Chem., Int. Ed. 2006, 45, 7803-7806
41. Steinhardt, S. E.; Silverston, J. S.; Vanderwal, C. D. J. Am. Chem. Soc. 2008, 130, 7560-7561
42. Michels, T. D.; Rhee, J. U.; Vanderwal, C. D. Org. Lett. 2008, 10, 4787-4790
43. Steinhardt, S. E.; Vanderwal, C. D. J. Am. Chem. Soc. 2009, 131, 7546-7547
44. Michels, T. D.; Kier, M. J.; Kearney, A. M.; Vanderwal, C. D. Org. Lett. 2010, 12, 3093-3095
45. Paton, R. S.; Steinhardt, S. E.; Vanderwal, C. D.; Houk, K. N. J. Am. Chem. Soc. 2011, 133, 3895-3905
46. Vanderwal, C. D. J. Org. Chem. 2011, 76, 9555-9567
47. Zincke, T. Liebigs Ann. Chem. 1903, 330, 361-374
48. Zincke, T. Liebigs Ann. Chem. 1904, 333, 296-345
49. Zincke, T.; Wurker, W. Liebigs Ann. Chem. 1905, 338, 107-141
50. König, W. J. Prakt. Chem. 1904, 69, 105-137
51. Ziegler, K.; Hafner, K. Angew. Chem. 1955, 67, 301
52. Köbrich, G.; Breckoff, W. E.; Drischel, W. Liebigs Ann. Chem. 1967, 704, 51-69
53. Kaiser, A.; Billot, X.; Gateau-Olesker, A.; Marazano, C.; Das, B. C. J. Am. Chem. Soc. 1998, 120, 8026-8034
54. Jakubowicz, K.; Ben Abdeljelil, K.; Herdemann, M.; Martin, M.-T.; Gateau-Olesker, A.; Al-Mourabit, A.; Marazano, C.; Das, B. C. J. Org. Chem. 1999, 64, 7381-7387
55. Wypych, J.-C.; Nguyen, T. M.; Nuhant, P.; Benechie, M.; Marazano, C. Angew. Chem., Int. Ed. 2008, 47, 5418-5421
56. Sinigaglia, I.; Nguyen, T. M.; Wypych, J.-C.; Delpech, B.; Marazano, C. Chem.-Eur. J. 2010, 16, 3594-3597
57. Rawal, V. H.; Michoud, C. Tetrahedron Lett. 1991, 32, 1695-1698
58. Rawal, V. H.; Michoud, C.; Monestel, R. F. J. Am. Chem. Soc. 1993, 115, 3030-3031
59. Martin, D. B. C.; Vanderwal, C. D. J. Am. Chem. Soc. 2009, 131, 3472-3473
60. González-Béjar, M.; Stiriba, S.-E.; Domingo, L. R.; Pérez-Prieto, J.; Miranda, M. A. J. Org. Chem. 2006, 71, 6932-6941
61. Haberl, U.; Steckhan, E.; Blechert, S.; Wiest, O. Chem.-Eur. J. 1999, 5, 2859-2865
62. Peglow, T.; Blechert, S.; Steckhan, E. Chem. Commun. 1999, 433-434
63. Bäckvall, J.-E.; Plobeck, N. A.; Juntunen, S. K. Tetrahedron Lett. 1989, 30, 2589-2592
64. Sato, S.; Fujino, T.; Isobe, H.; Nakamura, E. Bull. Chem. Soc. Jpn. 2006, 79, 1288-1292
65. Hsieh, M.-F.; Rao, P. D.; Liao, C.-C. Chem. Commun. 1999, 1441-1442
66. Rosenmund, P.; Hosseini-Merescht, M.; Bub, C. Liebigs Ann. Chem. 1994, 151-158
67. In contrast, dipolar cycloadditions of indoles are much more successful, and Boger has reported a fascinating [4 + 2]/1,3-dipolar cycloaddition cascade involving indole as the 2π component in the second reaction in their impressive synthesis of vindoline. Ishikawa, H.; Elliott, G. I.; Velcicky, J.; Choi, Y.; Boger, D. L. J. Am. Chem. Soc. 2006, 128, 10596-10612
68. Baldwin, J. E.; Claridge, T. D. W.; Culshaw, A. J.; Heupel, F. A.; Lee, V.; Spring, D. R.; Whitehead, R. C. Chem.-Eur. J. 1999, 5, 3154-3161 and references cited therein
69. A Zincke aldehyde-like compound [3-(3-indolyl)propenal] was found to be unreactive in Diels-Alder cycloadditions until the donor nature of the indole nitrogen was attenuated by N-tosylation. Even then, the reactivity was low. See: Kinsman, A. C.; Kerr, M. A. J. Am. Chem. Soc. 2003, 125, 14120-14125
70. Nuhant, P.; Raikar, S. B.; Wypych, J.-C.; Delpech, B.; Mazarano, C. J. Org. Chem. 2009, 74, 9413-9421
71. Bauld, N. L. Tetrahedron 1989, 45, 5307-5363
72. Markó, I. E.; Southern, J. M.; Adams, H. Tetrahedron Lett. 1992, 33, 4657-4660
73. Turet, L.; Markó, I. E.; Tinant, B.; Declercq, J.-P.; Touillaux, R. Tetrahedron Lett. 2002, 43, 6591-6595
74. Heureux, N.; Wouters, J.; Markó, I. E. Org. Lett. 2005, 7, 5245-5248
75. Büchi, G.; Matsumoto, K.; Nishimura, H. J. Am. Chem. Soc. 1971, 93, 3299-3301
76. Ando, M.; Büchi, G.; Ohnuma, T. J. Am. Chem. Soc. 1975, 97, 6880-6881
77. The Zincke reaction has been used to produce highly-colored cyanine dyes. For a review, see: Mishra, A.; Behera, R. K.; Behera, P. K.; Mishra, B. K.; Behera, G. B. Chem. Rev. 2000, 100, 1973-2011
78. Example of β-elimination of amine/amide from a dienolate: Dounay, A. B.; Humphreys, P. G.; Overman, L. E.; Wrobleski, A. D. J. Am. Chem. Soc. 2008, 130, 5368-5377
79. Cis -CE ring junction: Elliott, G. I.; Fuchs, J. R.; Blagg, S. J.; Ishikawa, H.; Tao, H.; Yuan, Z.-Q.; Boger., D. L. J. Am. Chem. Soc. 2006, 128, 10589-10595
80. Trans -CE ring junction: Dugat, D.; Benchekroun-Mounir, N.; Dauphin, G.; Gramain, J.-C. J. Chem. Soc., Perkin Trans. 1 1998, 2134-2150
81. Wypych, J.-C.; Nguyen, T. M.; Bénéchie, M.; Marazano, C. J. Org. Chem. 2008, 73, 1169-1172
82. Stauffacher, D. Helv. Chim. Acta 1961, 44, 2006-2015
83. Rakhimov, D. A.; Malikov, V. M.; Yusunov, C. Y. Khim. Prir. Soedin 1969, 5, 461-462
84. For NMR data, see: Clivio, P.; Richard, B.; Deverre, J.-R.; Sevenet, T.; Zeches, M.; Le Men-Oliver, L. Phytochemistry 1991, 30, 3785-3792
85. Crawley, G. C.; Harley-Mason, J. J. Chem. Soc. D., Chem. Commun. 1971, 685-686
86. Bonjoch, J.; Solé, D.; García-Rubio, S.; Bosch, J. J. Am. Chem. Soc. 1997, 119, 7230-7240
87. He, S. Ph.D. Dissertation (Rawal), University of Chicago, Chicago, IL, 2001.
88. Link, J. T. Organic Reactions; Wiley: Hoboken, NJ, 2002; Vol. 60, Chapter 2.
89. Birman, V. B.; Rawal, V. H. Tetrahedron Lett. 1998, 39, 7219-7222
90. Bennasar, M.-L.; Zulaica, E.; Solé, D.; Alonso, S. Chem. Commun. 2009, 3372-3374
91. Zu, L.; Boal, B. W.; Garg, N. K. J. Am. Chem. Soc. 2011, 133, 8877-8879
92. Solé, D.; Diaba, F.; Bonjoch, J. J. Org. Chem. 2003, 68, 5746-5749
93. Boonsombat, J.; Zhang, H.; Chughtai, M. J.; Hartung, J.; Padwa, A. J. Org. Chem. 2007, 73, 3539-3550
94. Zhang, D.; Song, H.; Qin, Y. Acc. Chem. Res. 2011, 44, 447-457
95. For a review of heterocycle synthesis using various Pd-catalyzed methods, see: Zeni, G.; Larock, R. C. Chem. Rev. 2006, 106, 4644-4680
96. For (Z)-1,2-dibromo-2-butene, see: Miyaura, N.; Ishikawa, M.; Suzuki, A. Tetrahedron Lett. 1992, 33, 2571-2574
97. Metz, P.; Linz, C. Tetrahedron 1994, 50, 3951-3966
98. Ilardi, E. A.; Stivala, C. E.; Zakarian, A. Org. Lett. 2008, 10, 1727-1730
99. Jeffery, T. Tetrahedron 1996, 52, 10113-10130
100. Lim, K.-H.; Low, Y.-Y.; Kam, T.-S. Tetrahedron Lett. 2006, 47, 5037-5039
101. Lim, K.-H.; Hiraku, O.; Komiyama, K.; Koyano, T.; Hayashi, M.; Kam, T.-S. J. Nat. Prod. 2007, 70, 1302-1307
102. For an early report on the role of Michael acceptors in cancer therapeutics, see: Kupchan, S. M.; Fessler, D. C.; Eakin, M. A.; Giacobbe, T. J. Science 1970, 168, 376-378
103. For a review of the Kopsia alkaloids, see: Kam, T.-S.; Lim, K.-H. In The Alkaloids: Chemistry and Biology; Cordell, G. G., Ed.; Elsevier: London, 2008; Vol. 66, pp 1-111.
104. In 2007, Padwa reported the first synthesis of valparicine using his Diels-Alder/fragmentation methodology. See: Boonsombat, J.; Zhang, H.; Chughtai, M. J.; Hartung, J.; Padwa, A. J. Org. Chem. 2007, 73, 3539-3550
105. The formyl groups in these vinylogous formamides do not behave like regular aldehydes in redox chemistry. For an example in the context of indole monoterpene aldehydes, see: Carroll, W. A.; Grieco, P. A. J. Am. Chem. Soc. 1993, 115, 1164-1165
106. Massiot, G.; Massousa, B.; Jacquier, M.-J.; Thepenier, P.; Le Men-Olivier, L.; Delaude, C.; Verpoorte, R. Phytochemistry 1988, 27, 3293-3304
107. Michoud, C. Ph.D. Dissertation (Rawal), The Ohio State University, OH, 1993.
108. Massiot, G.; Thépenier, P.; Jacquier, M.-J.; Lounkokobi, J.; Mirand, C.; Zèches, M.; Le Men-Olivier, L.; Delaude, C. Tetrahedron 1983, 39, 3645-3656
109. Wuts, P. G. M.; Greene, T. W. Greene's Protective Groups in Organic Synthesis, 4th ed.; Wiley: Hoboken, NJ, 2007; Chapter 7.
110. Zlotos, D. P. Eur. J. Org. Chem. 2004, 2375-2380
111. Zlotos, D. P.; Buller, S.; Stiefl, N.; Baumann, K.; Mohr, K. J. Med. Chem. 2004, 47, 3561-3571
112. Nussbaumer, P.; Baumann, K.; Dechat, T.; Harasek, M. Tetrahedron Lett. 1991, 47, 4591-4602
113. Olofsen, R. A.; Martz, J. T.; Senet, J.-P.; Piteau; Malfroot, T. J. Org. Chem. 1984, 49, 2081-2082
114. Yang, B. V.; O'Rourke, D.; Li, J. Synlett. 1993, 195-196
115. 2- group as a protecting group for a β-lactam, see: Heck, J. V.; Christenesen, B. G. Tetrahedron Lett. 1981, 22, 5027-5030
116. For its use for hydroxyl group protection, see: Ho, T.-L.; Hall, T. W. Synth. Commun. 1975, 5, 367-368
117. Garro-Helion, F.; Merzouk, A.; Guibé, F. J. Org. Chem. 1993, 58, 6109-6113
118. For a related preparation, see: Martin, S. F.; Williamson, S. A.; Gist, R. P.; Smith, K. M. J. Org. Chem. 1983, 48, 5170-5180
119. The phenallyl group (see 12i, Table 1, entry 9) was also an effective protecting group, providing similar yields in the deallylation/alkylation reaction. For a previous use of the phenallyl group as an amine protecting group, including its removal, see: Gommermann, N.; Knochel, P. Chem. Commun. 2005, 4175-4177
120. Blumenkopf; Overman, L. E. Chem. Rev. 1986, 86, 857-873
121. Overman, L. E.; Bell, K.; Ito, F. J. Am. Chem. Soc. 1984, 106, 4192-4201
122. Iminium catalysis: Lelais, G.; MacMillan, D. W. C. Aldrichim. Acta 2006, 39, 79-87
123. Knochel, P.; Betzemeier, B. In Modern Organocopper Chemistry; Krause, N., Ed.; Wiley-VCH: Weinheim, 2002; Chapter 2.
124. 3SnBr to give allenes, see: Eichberg, M. J.; Dorta, R. L.; Grotjahn, D. B.; Lamottke, K.; Schmidt, M.; Vollhardt, K. P. C. J. Am. Chem. Soc. 2001, 123, 9324-9337
125. Taguchi, H.; Ghoroku, K.; Tadaki, M.; Tsubouchi, A.; Takeda, T. J. Org. Chem. 2002, 67, 8450-8456
126. Taguchi, H.; Ghoroku, K.; Tadaki, M.; Tsubouchi, A.; Takeda, T. Org. Lett. 2001, 3, 3811-3814
127. Smith, A. B., III; Kim, W.-S.; Tong, R. Org. Lett. 2010, 12, 588-591
128. Smith, A. B., III; Tong, R.; Kim, W.-S.; Maio, W. A. Angew. Chem., Int. Ed. 2011, 50, 8904-8907
129. Trost, B. M.; Ball, Z. T. J. Am. Chem. Soc. 2005, 127, 17644-17655
130. Brook, A. G. Acc. Chem. Res. 1974, 7, 77-84
131. Herron, J. R.; Ball, Z. T. J. Am. Chem. Soc. 2008, 130, 16486-16487
132. Herron, J. R.; Russo, V.; Valente, E. J.; Ball, Z. T. Chem.-Eur. J. 2009, 15, 8713-8716
133. Russo, V.; Herron, J. R.; Ball, Z. T. Org. Lett. 2010, 12, 220-223
134. Lee, K.-S.; Hoveyda, A. H. J. Org. Chem. 2009, 74, 4455-4462
135. For a related reaction of a β-amino-aldehyde with diethyl malonate to give a similar malonamate, see: Abe, N.; Tanaka, K.; Yamagata, S.; Satoh, A.; Yamane, K. Bull. Chem. Soc. Jpn. 1992, 65, 340-344
136. Sirasani, G.; Andrade, R. B. Org. Lett. 2011, 13, 4736-4737 Curiously, the work in this recent paper allows for us to claim formal syntheses of racemic leuconicines A and B. The intermediate 15 from Sirasani and Andrade's paper, which they make enantioselectively in 10 steps and they convert to the natural products in three and four steps, respectively, is identical to our intermediate 36, which we made previously in four steps in racemic form for our norfluorocurarine synthesis
137. Nakao, Y.; Imanaka, H.; Chen, J.; Yada, A.; Hiyama, T. J. Organomet. Chem. 2007, 692, 585-603
138. Shindo, M.; Matsumoto, K.; Shishido, K. Synlett 2005, 176-179
139. Danheiser, R. L.; Renslo, A. R.; Amos, D. T.; Wright, G. T. Org. Synth. 2003, 80, 133-143
140. Joseph, S. B. M.Sc. Dissertation (Vanderwal), University of California, Irvine, CA, 2010.
141. Becher, J. Org. Synth. 1979, 59, 79-84
142. For a previous synthesis of phenallyl amines and their deprotection, see: Gommermann, N.; Knochel, P. Chem. Commun. 2005, 4175-4177
143. Becher, J. Synthesis 1980, 589-612
144. Jenkins, P. R.; Wilson, J.; Emmerson, D.; Garcia, M. D.; Smith, M. R.; Gray, S. J.; Britton, R. G.; Mahale, S.; Chaudhuri, B. Bioorg. Med. Chem. 2008, 16, 7728-7739
145. Sommer, L. H.; Bailey, D. L.; Goldberg, G. M.; Buck, C. E.; Bye, T. S.; Evans, F. J.; Whitmore, F. C. J. Am. Chem. Soc. 1954, 76, 1613-1618
146. Miniejew, C.; Outurquin, F.; Pannecoucke, X. Tetrahedron 2005, 61, 447-456
147. Kowalski, C. J.; Dung, J.-S. J. Am. Chem. Soc. 1980, 102, 7951-7953
148. Ohmura, T.; Masuda, K.; Takasa, I.; Suginome, M. J. Am. Chem. Soc. 2009, 131, 16624-16625
149. Mulzer, J.; Brüntrup, G.; Kühl, U.; Hartz, G. Chem. Ber. 1982, 115, 3453-3469
150. Yoshida, Y.; Sakakura, Y.; Aso, N.; Okada, S.; Tanabe, Y. Tetrahedron 1999, 55, 2183-2192
151. Falck, J. R.; Barma, D.; Mohaptra, S.; Bandyopadhyay, A.; Reddy, K. M.; Qi, J.; Campbell, W. Bioorg. Med. Chem. Lett. 2004, 14, 4987-4990
152. Pedras, M. S. C.; Jha, M. Bioorg. Med. Chem. 2006, 14, 4958-4979
153. Thompson, A. M.; Fry, D. W.; Kraker, A. J.; Denny, W. A. J. Med. Chem. 1994, 37, 598-609
154. Mewshaw, R. E.; Zhou, D.; Zhou, P.; Shi, X.; Hornby, G.; Spangler, T.; Scerni, R.; Smith, D.; Schechter, L. E.; Andree, T. H. J. Med. Chem. 2004, 47, 3823-3842
155. Kuehne, M. E.; Cowen, S. D.; Xu, F.; Borman, L. S. J. Org. Chem. 2001, 66, 5303-5316
156. Dai, W.-M.; Wu, J.; Fong, K. C.; Lee, M. Y. H.; Lau, C. W. J. Org. Chem. 1999, 64, 5062-5082
157. Loh, T.-P.; Cao, G.-Q.; Pei, J. Tetrahedron Lett. 1998, 39, 1453-1456
158. Krafft, M. E.; Cran, J. W. Synlett 2005, 1263-1266
159. Mori, A.; Danda, Y.; Fujii, T.; Hirabayashi, K.; Osakada, K. J. Am. Chem. Soc. 2001, 123, 10774-10775
160. Tong, R.; Valentine, J. C.; McDonald, F. E.; Fang, X.; Hardcastle, K. I. J. Am. Chem. Soc. 2007, 129, 1050-1051