Continuum of mechanisms for nucleophilic substitutions of cyclic acetals

Organic Letters

Volumn 10, Issue 21, 2008, Pages 4907-4910

  Krumper, Jennifer R ^a   Salamant, Walter A ^a   Woerpel, K A ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ACETAL DERIVATIVE;

ARTICLE; CHEMICAL MODEL; CHEMICAL STRUCTURE; CHEMISTRY; CYCLIZATION; STATIC ELECTRICITY; STEREOISOMERISM; SYNTHESIS;

ACETALS; CYCLIZATION; MODELS, CHEMICAL; MOLECULAR STRUCTURE; STATIC ELECTRICITY; STEREOISOMERISM;

EID: 58149154432     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol8019956     Document Type: Article

References (38)

1. Garcia, B. A.; Gin, D. Y. J. Am. Chem. Soc. 2000, 122, 4269-4279.
2. Sammakia, T.; Smith, R. S. J. Am. Chem. Soc. 1994, 116, 7915-7916.
3. Boebel, T. A.; Gin, D. Y. J. Org. Chem. 2005, 70, 5818-5826.
4. Kim, J.-H.; Yang, H.; Park, J.; Boons, G.-J. J. Am. Chem. Soc. 2005, 127, 12090-12097.
5. Nukada, T.; Berces, A.; Zgierski, M. Z.; Whitfield, D. M. J. Am. Chem. Soc. 1998, 120, 13291-13295.
6. Berces, A.; Enright, G.; Nukada, T.; Whitfield, D. M. J. Am. Chem. Soc. 2001, 123, 5460-5464.
7. Fan, E.; Shi, W.; Lowary, T. L. J. Org. Chem. 2007, 72, 2917-2928.
8. Banait, N. S.; Jencks, W. P. J. Am. Chem. Soc. 1991, 113, 7951-7958.
9. Crich, D.; Chandrasekera, N. S. Angew. Chem., Int. Ed. 2004, 43, 5386-5389.
10. El-Badri, M. H.; Willenbring, D.; Tantillo, D. J.; Gervay-Hague, J. J. Org. Chem. 2007, 72, 4663-4672.
11. Crich, D.; Sun, S. J. Org. Chem. 1996, 61, 4506-4507.
12. Crich, D.; Li, L. J. Org. Chem. 2007, 72, 1681-1690.
13. Minehan, T. G.; Kishi, Y. Tetrahedron Lett. 1997, 38, 6815-6818.
14. Brown, D. S.; Bruno, M.; Davenport, R. J.; Ley, S. V. Tetrahedron 1989, 45, 4293-4308.
15. Crich, D.; Pedersen, C. M.; Bowers, A. A.; Wink, D. J. J. Org. Chem. 2007, 72, 1553-1565.
16. Vankar, Y. D.; Vankar, P. S.; Behrendt, M.; Schmidt, R. R. Tetrahedron 1991, 47, 9985-9992.
17. Mayr, H.; Kempf, B.; Ofial, A. R. Acc. Chem. Res. 2003, 36, 66-77.
18. 3SiOTf (1.6 equiv) under standard reaction conditions. The ester trans-4 did not react under these conditions: neither stereochemical inversion to cis-4 nor chemical exchange to form cis- or trans-6 was observed.
19. Romero, J. A. C.; Tabacco, S. A.; Woerpel, K. A. J. Am. Chem. Soc. 2000, 122, 168-169.
20. Ayala, L.; Lucero, C. G.; Romero, J. A. C.; Tabacco, S. A.; Woerpel, K. A. J. Am. Chem. Soc. 2003, 125, 15521-15528.
21. Shenoy, S. R.; Woerpel, K. A. Org. Lett. 2005, 7, 1157-1160.
22. Mayr, H.; Ofial, A. R. Angew. Chem., Int. Ed. 2006, 45, 1844-1854.
23. Winstein, S.; Grunwald, E.; Jones, H. W. J. Am. Chem. Soc. 1951, 73, 2700-2707,
24. Jencks, W. P. Acc. Chem. Res. 1980, 13, 161-169.
25. Richard, J. P.; Jencks, W. P. J. Am. Chem. Soc. 1982, 104, 4689-4691.
26. Ta-Shma, R.; Rappoport, Z. J. Am. Chem. Soc. 1983, 105, 6082-6095.
27. Denmark, S. E.; Almstead, N. G. J. Org. Chem. 1991, 56, 6485-6487.
28. Crich, D.; Sun, S. J. Am. Chem. Soc. 1997, 119, 11217-11223.
29. N2 substitution to form cis products, (b) Anomeric isomers of triflate II are formed reversibly and interconvert rapidly via an oxocarbenium ion intermediate, presumably in a solvent cage with the triflate counterion. Cis selectivity, in this case, arises from a preference for reaction through trans diaxial triflate II. Attempts to observe triflate II at low temperature have been unsuccessful thus far.
30. Suzuki, S.; Matsumoto, K.; Kawamura, K.; Suga, S.; Yoshida, J. Org. Lett. 2004, 6, 3755-3758.
31. 2 (1.6 equiv). The ester cis-4 did not react under these conditions: neither stereochemical inversion to trans-4 nor chemical exchange to form cis- or trans-6 was observed.
32. Shenoy, S. R.; Smith, D. M.; Woerpel, K. A. J. Am. Chem. Soc. 2006, 128, 8671-8677.
33. Bartl, J.; Steenken, S.; Mayr, H.; McClelland, R. A. J. Am. Chem. Soc. 1990, 112, 6918-6928.
34. 2-mediated conditions to ion pairing with the acetate counterion. This hypothesis is buttressed by our results with the pivaloate substrate 17 (vide infra).
35. eq, addition to the top face (pathway a) is at the diffusion limit, while addition to the bottom face (pathway b) occurs with a rate that is slightly below the diffusion limit. This scenario leads to a reduced, but not completely eroded, selectivity.
36. Manoharan, M.; Eliel, E. L. Tetrahedron Lett. 1984, 25, 3267-3268.
37. Diastereoselectivities were consistent with the data in Tables 1 and 2.
38. All substitutions of pivaloate 17 gave diastereoselectivities similar to those of acetate 1, as detailed in the Supporting Information.