Concise, improved procedure for the synthesis of brassinolide and some novel side-chain analogues

Journal of Organic Chemistry

Volumn 62, Issue 4, 1997, Pages 1179-1182

  Back, Thomas G ^a   Baron, Denise L ^a   Luo, Weide ^a   Nakajima, Suanne K ^a  

^a UNIVERSITY OF CALGARY   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

BRASSINOLIDE; BRASSINOSTEROID; STEROID; UNCLASSIFIED DRUG;

ARTICLE; DRUG SYNTHESIS; IN VITRO STUDY; MASS SPECTROMETRY; NUCLEAR MAGNETIC RESONANCE; REACTION ANALYSIS; STEREOCHEMISTRY;

EID: 0030972058     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo961854y     Document Type: Article

References (35)

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3. For recent examples, see: (a) Li, J.; Nagpal, P.; Vitart, V.; McMorris, T. C.; Chory, J. Science 1996, 272, 398. (b) Clouse, S. D.; Langford, M.; McMorris, T. C. Plant Physiol. 1996, 111, 671.
4. For recent examples, see: (a) Li, J.; Nagpal, P.; Vitart, V.; McMorris, T. C.; Chory, J. Science 1996, 272, 398. (b) Clouse, S. D.; Langford, M.; McMorris, T. C. Plant Physiol. 1996, 111, 671.
5. For recent reviews, see: (a) Back, T. G. In Studies in Natural Products Chemistry; Atta-ur-Rahman, Ed.; Elsevier: Amsterdam, 1995; Vol. 16, pp 321-364. (b) McMorris, T. C.; Donaubauer, J. R.; Silveira, M. H.; Molinski, T. F. In ref 2; Chapter 4. (c) Khripach, V. A.; Zhabinskii, V. N.; Litvinovskaya, R. P. In ref 2; Chapter 5.
6. For recent reviews, see: (a) Back, T. G. In Studies in Natural Products Chemistry; Atta-ur-Rahman, Ed.; Elsevier: Amsterdam, 1995; Vol. 16, pp 321-364. (b) McMorris, T. C.; Donaubauer, J. R.; Silveira, M. H.; Molinski, T. F. In ref 2; Chapter 4. (c) Khripach, V. A.; Zhabinskii, V. N.; Litvinovskaya, R. P. In ref 2; Chapter 5.
7. For recent reviews, see: (a) Back, T. G. In Studies in Natural Products Chemistry; Atta-ur-Rahman, Ed.; Elsevier: Amsterdam, 1995; Vol. 16, pp 321-364. (b) McMorris, T. C.; Donaubauer, J. R.; Silveira, M. H.; Molinski, T. F. In ref 2; Chapter 4. (c) Khripach, V. A.; Zhabinskii, V. N.; Litvinovskaya, R. P. In ref 2; Chapter 5.
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11. For lead references to structure-activity studies of brassinosteroids, see: (a) Adam, G.; Marquardt, V.; Vorbrodt, H. M.; Hörhold, C.; Andreas, W.; Gartz, J. In ref 2; Chapter 7. (b) Brosa, C.; Capdevila, J. M.; Zamora, I. Tetrahedron 1996, 52, 2435.
12. Back, T. G.; Blazecka, P. G.; Krishna, M. V. Can. J. Chem. 1993, 71, 156.
13. One side-chain analogue (25-homobrassinolide) was recently reported to have greater activity than brassinolide itself: Mori, K.; Takeuchi, T. Liebigs Ann. Chem. 1988, 815.
14. 2S workup, 85%.
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17. For reviews of selenium-stabilized carbanions, see: (a) Krief, A. In The Chemistry of Organic Selenium and Tellurium Compounds; Patai, S., Ed.; Wiley: Chichester, 1987; Volume 2, Chapter 17. ( b) Reich, H. J. In Organoselenium Chemistry; Liotta, D., Ed.; Wiley: New York, 1987; Chapter 5. (c) Paulmier, C. Selenium Reagents and Intermediates in Organic Synthesis; Pergamon Press: Oxford, 1986; Chapter 9.
18. (a) For a discussion of the stereochemistry of additions of nucleophiles to aldehydes, see: Eliel, E. L.; Wilen, S. H.; Mander, L. N. Stereochemistry of Organic Compounds; Wiley: New York, 1994; pp 876-888. (b) For an example of a different stereoselective propenylation of a less elaborated steroidal C-22 aldehyde, see: Tsukamoto, M.; Iio, H.; Tokoroyama, T. Tetrahedron Lett. 1987, 28, 4561.
19. (a) For a discussion of the stereochemistry of additions of nucleophiles to aldehydes, see: Eliel, E. L.; Wilen, S. H.; Mander, L. N. Stereochemistry of Organic Compounds; Wiley: New York, 1994; pp 876-888. (b) For an example of a different stereoselective propenylation of a less elaborated steroidal C-22 aldehyde, see: Tsukamoto, M.; Iio, H.; Tokoroyama, T. Tetrahedron Lett. 1987, 28, 4561.
20. Selenoxide syn eliminations proceed with high regioselectivity away from oxygen substituents and generally favor the trans isomer when the product is a 1,2-disubstituted olefin. See (a) ref 11c, Chapter 5. (b) Back, T. G. In The Chemistry of Organic Selenium and Tellurium Compounds; Patai, S., Ed.; Wiley: Chichester, 1987; Volume 2, Chapter 3.
21. Selenoxide syn eliminations proceed with high regioselectivity away from oxygen substituents and generally favor the trans isomer when the product is a 1,2-disubstituted olefin. See (a) ref 11c, Chapter 5. (b) Back, T. G. In The Chemistry of Organic Selenium and Tellurium Compounds; Patai, S., Ed.; Wiley: Chichester, 1987; Volume 2, Chapter 3.
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29. When the reaction was run under more concentrated conditions, substantial amounts of the allylic alcohol 4 were also produced, resulting in poorer yields of 6.
30. Trifluoroperoxyacetic acid is the reagent of choice for the Baeyer-Villiger oxidation of many 6-ketosteroids; for examples see ref 4a, pp 329-330. A similar procedure was employed by McMorris et al. (ref 5) for the Baeyer-Villiger oxidation of a 2,3,22,23-tetrahydroxycampestan-6-one diacetonide.
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34. Recrystallization of the nonpolar fractions from ethanol permitted recovery of 70-90% of diphenyl diselenide.
35. The electron impact mass spectra of the tetrols 11 and 12 did not show their molecular ions. The mass spectra are therefore reported for the corresponding tetraacetates, which were prepared by treating 11 and 12 with acetic anhydride and 4-(dimethylamino)pyridine in pyridine for 4 h at room temperature.