α,α-Disubstituted Boron Enolates in the Asymmetric Synthesis of Quaternary Carbon Centers

Organic Letters

Volumn 6, Issue 3, 2004, Pages 405-407

  Burke, E Diane ^a   Gleason, James L ^a  

^a MCGILL UNIVERSITY   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

ALDEHYDE; AMIDE; BORON DERIVATIVE; CARBON; PHENYL GROUP; THIOGLYCOLIC ACID DERIVATIVE;

ARTICLE; REDUCTION; STEREOCHEMISTRY; SYNTHESIS;

EID: 1342285523     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0364428     Document Type: Article

References (22)

1. For approaches to this problem using allylmetal species, see: (a) Kennedy, J. W. J.; Hall, D. G. J. Am. Chem. Soc. 2002, 124, 898. (b) Denmark, S. E.; Fu, J. J. Am. Chem. Soc. 2001, 123, 9488. For an alkylation approach, see: (c) Frater, G. Helv. Chim. Acta 1979, 62, 2825, 2829.
2. For approaches to this problem using allylmetal species, see: (a) Kennedy, J. W. J.; Hall, D. G. J. Am. Chem. Soc. 2002, 124, 898. (b) Denmark, S. E.; Fu, J. J. Am. Chem. Soc. 2001, 123, 9488. For an alkylation approach, see: (c) Frater, G. Helv. Chim. Acta 1979, 62, 2825, 2829.
3. For approaches to this problem using allylmetal species, see: (a) Kennedy, J. W. J.; Hall, D. G. J. Am. Chem. Soc. 2002, 124, 898. (b) Denmark, S. E.; Fu, J. J. Am. Chem. Soc. 2001, 123, 9488. For an alkylation approach, see: (c) Frater, G. Helv. Chim. Acta 1979, 62, 2825, 2829.
4. Manthorpe, J. M.; Gleason, J. L. J. Am. Chem. Soc. 2001, 123, 2091.
5. Manthorpe, J. M.; Gleason, J. L. Angew. Chem., Int. Ed. 2002, 41, 2338.
6. For purposes of convenience, the syn product is defined as the one with the larger group at the α-position and the hydroxyl group both forward when drawn in an extended format.
7. Crowden, C. J.; Patterson, I. Org. React. 1997, 51, 1.
8. Although simple amides have not been reported to undergo enolboration, N-acyl isoxazolidines have been shown to be useful substrates. See: Abiko, A.; Liu, J.-F.; Wang, G.-Q.; Masamune, S. Tetrahedron Lett. 1997, 38, 3261.
9. Haubenrieich, T.; Hünig, S.; Schulz, H.-J. Angew. Chem., Int. Ed. Engl. 1993, 32, 398. Fringuelli, F.; Piermatti, O.; Pizzo, F. J. Org. Chem. 1995, 60, 7006. Vicario, J. L.; Badia, D.; Dominguez, E.; Rodriguez, M.; Carrillo, L. J. Org. Chem. 2000, 65, 3754. For a recent example of transmetalation from a sodium enolate, see: Lang, F.; Zewge, D.; Song, Z. J.; Biba, M.; Dormer, P.; Tschaen, D.; Volante, R. P.; Reider, P. J. Tetrahedron Lett. 2003, 44, 5285. For transmetalation from copper, see: Lipshutz, B. H.; Papa, P. Angew. Chem., Int. Ed. 2002, 41, 4580.
10. Haubenrieich, T.; Hünig, S.; Schulz, H.-J. Angew. Chem., Int. Ed. Engl. 1993, 32, 398. Fringuelli, F.; Piermatti, O.; Pizzo, F. J. Org. Chem. 1995, 60, 7006. Vicario, J. L.; Badia, D.; Dominguez, E.; Rodriguez, M.; Carrillo, L. J. Org. Chem. 2000, 65, 3754. For a recent example of transmetalation from a sodium enolate, see: Lang, F.; Zewge, D.; Song, Z. J.; Biba, M.; Dormer, P.; Tschaen, D.; Volante, R. P.; Reider, P. J. Tetrahedron Lett. 2003, 44, 5285. For transmetalation from copper, see: Lipshutz, B. H.; Papa, P. Angew. Chem., Int. Ed. 2002, 41, 4580.
11. Haubenrieich, T.; Hünig, S.; Schulz, H.-J. Angew. Chem., Int. Ed. Engl. 1993, 32, 398. Fringuelli, F.; Piermatti, O.; Pizzo, F. J. Org. Chem. 1995, 60, 7006. Vicario, J. L.; Badia, D.; Dominguez, E.; Rodriguez, M.; Carrillo, L. J. Org. Chem. 2000, 65, 3754. For a recent example of transmetalation from a sodium enolate, see: Lang, F.; Zewge, D.; Song, Z. J.; Biba, M.; Dormer, P.; Tschaen, D.; Volante, R. P.; Reider, P. J. Tetrahedron Lett. 2003, 44, 5285. For transmetalation from copper, see: Lipshutz, B. H.; Papa, P. Angew. Chem., Int. Ed. 2002, 41, 4580.
12. Haubenrieich, T.; Hünig, S.; Schulz, H.-J. Angew. Chem., Int. Ed. Engl. 1993, 32, 398. Fringuelli, F.; Piermatti, O.; Pizzo, F. J. Org. Chem. 1995, 60, 7006. Vicario, J. L.; Badia, D.; Dominguez, E.; Rodriguez, M.; Carrillo, L. J. Org. Chem. 2000, 65, 3754. For a recent example of transmetalation from a sodium enolate, see: Lang, F.; Zewge, D.; Song, Z. J.; Biba, M.; Dormer, P.; Tschaen, D.; Volante, R. P.; Reider, P. J. Tetrahedron Lett. 2003, 44, 5285. For transmetalation from copper, see: Lipshutz, B. H.; Papa, P. Angew. Chem., Int. Ed. 2002, 41, 4580.
13. Haubenrieich, T.; Hünig, S.; Schulz, H.-J. Angew. Chem., Int. Ed. Engl. 1993, 32, 398. Fringuelli, F.; Piermatti, O.; Pizzo, F. J. Org. Chem. 1995, 60, 7006. Vicario, J. L.; Badia, D.; Dominguez, E.; Rodriguez, M.; Carrillo, L. J. Org. Chem. 2000, 65, 3754. For a recent example of transmetalation from a sodium enolate, see: Lang, F.; Zewge, D.; Song, Z. J.; Biba, M.; Dormer, P.; Tschaen, D.; Volante, R. P.; Reider, P. J. Tetrahedron Lett. 2003, 44, 5285. For transmetalation from copper, see: Lipshutz, B. H.; Papa, P. Angew. Chem., Int. Ed. 2002, 41, 4580.
14. α,α-Disubstituted boron enolates prepared by treatment of silyl enol ethers with dibutylboron triflate have been reported to give high diastereoselectivity in aldol condensations. See: Yamago, S.; Machii, D.; Nakamura, E. J. Org. Chem. 1991, 56, 2098.
15. The corresponding anti aldol products could not be produced with high selectivity. Similar low selectivity was observed in the alkylations of (E)-enolates using this auxiliary system (ref 3).
16. (a) Myers, A. G.; Yang, B. H.; Kopecky, D. J.; Tetrahedron Lett. 1996, 37, 3623.
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18. Due to complications from retro-aldol processes, this reduction only works on the free (unbenzylated) thiols. These intermediates are easily isolated directly from the aldol reaction mixture.
19. The pendant thioethylene chain presumably complexes to 1 equiv of the boron reagent, thus creating the possibility of an internal Lewis acid-directed aldol. For examples of external Lewis acids in boron aldols, see: (a) Danda, H. ; Hansen, M. M.; Heathcock, C. H. J. Org. Chem. 1990, 55, 173. (b) Walker, M. A.; Heathcock, C. H. J. Org. Chem. 1991, 56, 5747.
20. The pendant thioethylene chain presumably complexes to 1 equiv of the boron reagent, thus creating the possibility of an internal Lewis acid-directed aldol. For examples of external Lewis acids in boron aldols, see: (a) Danda, H. ; Hansen, M. M.; Heathcock, C. H. J. Org. Chem. 1990, 55, 173. (b) Walker, M. A.; Heathcock, C. H. J. Org. Chem. 1991, 56, 5747.
21. (a) Kim, Y.-J.; Streitwieser, A.; Chow, A.; Fraenkel, G. Org. Lett. 1999, 1, 2069.
22. (b) Pugh, J. K.; Streitwieser, A. J. Org. Chem. 2001, 66, 1334.