Stereoselection in the prins-pinacol synthesis of acyltetrahydrofurans

Organic Letters

Volumn 3, Issue 8, 2001, Pages 1225-1228

  Cohen, Frederick ^a   MacMillan, David W C ^a,b   Overman, Larry E ^a   Romero, Alex ^a,c  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b CALIFORNIA INSTITUTE OF TECHNOLOGY   (United States)

^c Optimer Pharmaceuticals Inc   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

FURAN DERIVATIVE; TETRAHYDROFURAN;

ARTICLE; CHEMICAL MODEL; METHODOLOGY; ORGANIC CHEMISTRY; SYNTHESIS; TIME;

CHEMISTRY, ORGANIC; FURANS; MODELS, CHEMICAL; TIME FACTORS;

EID: 0035912325     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0157003     Document Type: Article

References (34)

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4. (b) Brown, M. J.; Harrison, T.; Herrinton, P. M.; Hopkins, M. H.; Hutchinson, K. D.; Mishra, P.; Overman, L. E. J. Am. Chem. Soc. 1991, 113, 5365-5378.
5. (c) Overman, L. E.; Rishton, G. M. Organic Syntheses; Wiley: New York, 1998; Collect. Vol. IX, pp 4-9.
6. For the discovery of this route to tetrahydrofurans, see: Martinet, P.; Mousset, G. Bull. Soc. Chim. Fr. 1970, 1071-1076.
7. (a) Brown, M. J.; Harrison, T.; Overman, L. E. J. Am. Chem. Soc. 1991, 113, 5378-5384.
8. (b) Grese, T. A.; Hutchinson, K. D.; Overman, L. E. J. Org. Chem. 1993, 58, 2468-2477.
9. (c) MacMillan, D. W. C.; Overman, L. E. J. Am. Chem. Soc. 1995, 117, 10391-10392.
10. (d) Hanaki, N.; Link, J. T.; MacMillan, D. W. C.; Overman, L. E.; Trankle, W. G.; Wurster, J. A. Org. Lett. 2000, 2, 223-226.
11. (e) Overman, L. E.; Pennington, L. D. Org. Lett. 2000, 2, 2683-2686.
12. 7
13. (a) Bartok, M.; Molnar, A. In Chemistry of Ethers, Crown Ethers, Hydroxyl Compounds and Their Sulfur Analogues; Patai, S., Ed.; Wiley: New York, 1980; Part 2, pp 722-732.
14. (b) Rickborn, B. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 3, pp 721-732.
15. Minor, K. P.; Overman, L. E. Tetrahedron 1997, 53, 8927-8940.
16. (a) Cremer, D.; Gauss, J.; Childs, R. F.; Blackburn, C. J. Am. Chem. Soc. 1985, 107, 2435-2441.
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18. 10b
19. (a) Still, W. C.; MacDonald, J. H., III. Tetrahedron Lett. 1980, 21, 1031-1034.
20. (b) Overman, L. E.; Rishton, G. M. Organic Syntheses; Wiley: New York, 1998; Collect. Vol. IX, pp 139-142.
21. In 94-99% isomeric purity by capillary GLC analysis.
22. Romero, A. Ph.D. Dissertation, University of California, Irvine. 1998.
23. Eliel, E. L., Binsh, G.; Willey, W. J. J. Am. Chem. Soc. 1970, 92, 5394-5402.
24. 4-promoted reactions led to lower reaction rates.
25. Isomer ratios were determined by capillary GLC analysis and are mean values of 2-4 experiments. When the minor isomer was not detected, the ratio is shown as >99:1.
26. 3N. Acyltetrahydrofurans 12b and 13b were isolated in a 1.2:1 ratio and 61% combined yield, and acetals 7s and 7a were recovered in a 1.6:1 ratio (31% combined yield). This result demonstrates that the anti stereoisomer reacts slightly faster and confirms that 7s would have been detected, if epimerization of 7a → 7s had been occurring under the rearrangement conditions (Table 2, entry 4).
27. (a) Additional evidence for the cis relationship of the acetyl and C2 methyl groups of 12a was obtained by exposing 12a to methanolic KOH at room temperature for 24 h to give 12a and its C3 acetyl epimer in a ratio of 8:92. Similar treatment of 13d provided an 84:16 ratio 13d and its C3 epimer under identical conditions, consistent with the acetyl and C2 substituents being trans in 13d.
28. (b) The stereostructure of the major acyltetrahydrofuran product formed from a congener of 13c was secured by single-crystal X-ray analysis of the thiosemicarbazone derivative; see: MacMillan, D. W. C. Ph.D. Dissertation, University of California, Irvine, 1996.
29. For reviews, see: (a) Houk, K. N.; Paddon-Row, M. N.; Rondan, N. G.; Wu, Y. D.; Brown, F. K.; Spellmeyer, D. C.; Metz, J. T.; Li, Y.; Loncharich, R. J. Science 1986, 231, 1108-1117.
30. (b) Hoveyda, A. H.; Evans, D. A.; Fu, G. C. Chem. Rev. 1993, 93, 1307-1370.
31. (c) For an alternate analysis, see: Kahn, S. D.; Pau, C. F.; Chamberlin, A. R.; Hehre, W. J. J. Am. Chem. Soc. 1987, 109, 650-663.
32. Hammond, G. S. J. Am. Chem. Soc. 1955, 77, 334-338.
33. Transition states found at the 6-31G* level are consistent with the transition state of the Prins cyclization being later in the vinyl i than the propenyl ii series (black = carbon, dotted = oxygen, clear = hydrogen; only the internal hydrogen of the vinyl group is shown). The dihedral angle between the developing p orbital and the σ bond to the methyl group at the original allylic carbon is 43.1° in i and 47.9° in ii. (matrix presented)
34. 4 faster than 1-substituted alkenes; see: Mayr, H.; Patz, M. Angew. Chem., Int. Ed. Engl. 1994, 33, 938-957.