Boron-mediated double aldol reaction of carboxylic esters [10]

Journal of the American Chemical Society

Volumn 121, Issue 30, 1999, Pages 7168-7169

  Abiko, Atsushi ^a   Liu, Ji Feng ^b   Buske, Dana C ^b   Moriyama, Satoshi ^a   Masamune, Satoru ^b  

^a KYOTO INSTITUTE OF TECHNOLOGY   (Japan)

^b MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CHEMICAL ANALYSIS; CHEMICAL BINDING; CHEMICAL REACTION; CHEMICAL STRUCTURE; LETTER; STRUCTURE ANALYSIS;

EID: 0033523219     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9914184     Document Type: Letter

References (15)

1. Abiko, A.; Liu, J.-F.; Masamune, S. J. Org. Chem. 1996, 61, 2590.
2. Abiko, A.; Liu, J.-F.; Masamune, S. J. Am. Chem. Soc. 1997, 119, 2586.
3. Liu, J.-F.; Abiko, A.; Pei, Z.; Buske, D. C.; Masamune, S. Tetrahedron Lett. 1998, 39, 1873.
4. X-ray data in Supporting Information.
5. 5a-C is possibly produced from both diastereomers of the mono-aldolate. For a detailed discussion of the stereochemistry of the double aldol reaction and information to support a cyclic transition state involving an E(O)-enolate, see the Supporting Information.
6. (a) Moberg, C. Angew. Chem., Int. Ed. 1998, 37, 248.
7. (b) Nugent, W. A. J. Am. Chem. Soc. 1998, 120, 7139 and references therein.
8. Lütjens, H.; Wahl, G.; Möller, F.; Knochel, P.; Sundermeyer, J. Organometallics 1997, 16, 5869.
9. The reaction with EtCHO produced 5b-A:5b-B:5b-C = 89:3:8 in 95% yield, from which 5b-A of 94% de was obtained by chromatography. In the subsequent step, diastereomerically pure acetonide 6b-A was isolated by recrystallization. The reaction with PhCHO produced 5c-A:5c-B:5c-C = 85: 1:14 in 97% yield, from which 5c-A was isolated by recrystallization. For characterization and determination of the absolute stereochemistry of 5b-A and 5c-A, see the Supporting Information.
10. For oxidation of 7c-A, pyridinium chlorochromate was used instead of pyridinium dichromate.
11. With i-PrMgCl, reduction product 7a-A was obtained in 35% yield.
12. Compare with: Luke, G. P.; Morris, J. J. Org. Chem. 1995, 60, 3013.
13. Only this mono-aldolate species is responsible for the double aldol reaction. This species seems to be rather labile and readily decomposed, thus allowing for the formation of mono-aldol products. Indeed, when the aldehyde was added rapidly, a significant amount of the mono-aldol product 4 was formed.
14. The oligomeric form of boron triflate, with a dimeric diboradioxetane structure, may be responsible for the enolization of carboxylic esters. See, Ooi, T.; Uraguchi, D.; Maruoka, K. Tetrahedron Lett. 1998, 39, 8105. (Matrix Presented)
15. It is not clear that the boron species described in ref 13 is incorporated in the aldol reaction of propionate esters in general. The failure of the double aldol reaction for propionate ester 1 and 2 very likely be attributed to the steric reason.