Progressive-convergent elucidation of stereochemistry in complex polyols. The absolute configuration of (-)-sagittamide A

Journal of the American Chemical Society

Volumn 128, Issue 36, 2006, Pages 11764-11765

  Lievens, Sarah C ^a   Molinski, Tadeusz F ^a,b  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DICARBOXYLIC ACID; POLYOL; SAGITTAMIDE A; UNCLASSIFIED DRUG;

ARTICLE; CARBON NUCLEAR MAGNETIC RESONANCE; CHEMICAL STRUCTURE; CIRCULAR DICHROISM; EXCITON COUPLING CIRCULAR DICHROISM; STEREOCHEMISTRY;

CIRCULAR DICHROISM; MOLECULAR CONFORMATION; NUCLEAR MAGNETIC RESONANCE, BIOMOLECULAR; ORNITHINE; STEREOISOMERISM; VALINE;

EID: 33748503605     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja063735y     Document Type: Article

References (19)

1. Lievens, S. C.; Molinski, T. F. Org. Lett. 2005, 7(11), 2281-2284.
2. All attempts to convert 1 to a C1-O5 δ-lactone (potentially useful for stereochemical assignment) using acid catalysis were unsuccessful.
3. Murata, M.; Nakamura, H.; Tachibana, K. J. Org. Chem. 1999, 64, 866-876.
4. (a) Kobayashi, Y.; Hayashi, N.; Kishi, Y. Org Lett. 2002, 4, 411-414.
5. (b) Kobayashi, Y.; Tan, C.-H.; Kishi, Y. J. Am. Chem. Soc. 2001, 123, 2076-2078.
6. (c) Kobayashi, Y.; Lee, J.; Tezuka, K.; Kishi, Y. Org. Lett. 1999, 1, 2177-2180.
7. (a) Vazquez, J. T.; Wiesler, W. T.; Nakanishi, K. J. Am. Chem. Soc. 1987, 109, 5586-5592.
8. (b) Zhou, P.; Berova, N.; Nakanishi, K.; Knani, M.; Rohmer, M. J. Am. Chem. Soc. 1991, 113, 4040-4042.
9. (c) Harada, N.; Nakanishi, K. Circular Dichroic Spectroscopy: Exciton Coupling in Organic Stereochemistry: University Science Books: Mill Valley, CA, 1983.
10. The carbons numbered C7, C8, and C9 in 1 map to C4, C3, and C2 of ribose or xylose, respectively. Thus, the stereochemical descriptors 'xylo-' and 'ribo-' in the context of this work refer to C7-C9 of 1.
11. The configuration of the major isomer was assigned by analogy with the well-known 1,2-syn-stereopreference for 1n°-promoted allylation of aldohexoses [(a) Kim, E.; Gordon, D. M.; Schmid, W.; Whitesides, G. M. J. Chem. Org. 1993, 58, 5500-5507.
12. (b) Kobayashi, S.; Nagayama, S. J. Org. Chem. 1996, 61, 2256-2257] and subsequent conversion to the acetonides 10 and 11.
13. 2.
14. Blakemore, P. R.; Cole, W. J.; Kocienski, P. J.; Morley, A. Synlett 1998, (1), 26-28. Both 14 and 15 were prepared from δ-valerolactone in three and four steps, respectively (see S1).
15. 13C NMR spectra of 2 and 8 (see S1).
16. This observation suggests caution in using J-based methodology and overreliance on the underlying assumption of all-staggered conformations and the accuracy of J's measured in strongly coupled contiguous polyols that may not be amenable to first-order spin analysis.
17. 2, MeOH-ether, ref 1) and the hexaols corresponding to 6 and 7 were each converted (excess BzCl, pyridine, 40 °C) to hexabenzoates 17, 18, and 19, respectively, after HPLC purification. Benzoylation at higher temperatures (60-90 °C) led to significant formation of tetrabenzoyloxy-tetrahydrofuran.
18. The similarity of CD spectra of diastereomeric 19 and 20 reflect the dominance of the C7-C10 configuration on the Cotton effects.
19. Rychnovsky, S. D.; Rogers, B.; Yang, G. J. Org. Chem. 1993, 58, 3511-3515.