Functionalized triarylcarbenium ions as catalysts in mukaiyama aldol addition: Effects of counter ions and silyl groups on the intervention of silyl catalysis

Synlett

Volumn , Issue 8, 1998, Pages 924-926

  Chen, Chien Tien ^a   Chao, Shi Deh ^a   Yen, Kuao Chung ^a  

^a NATIONAL TAIWAN NORMAL UNIVERSITY   (Taiwan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0042438583     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-1998-1815     Document Type: Article

References (19)

1. (a) Kobayashi, S. Kagaku To Kogyo 1989, 42, 245 and references therein.
2. (b) Kobayashi, S.; Nagayama, S. J. Am. Chem. Soc. 1997, 119, 10049.
3. 3SiOTf mediated aldols: (a) Mukai, C.; Hashizume, S.; Nagami, K.; Hanaoka, M. Chem. Pharm. Bull. 1990, 38, 1509.
4. (b) Murata, S.; Suzuki, M.; Noyori, R. Tetrahedron 1988, 44, 4259.
5. Hollis, T. K.; Bosnish, B. J. Am. Chem. Soc. 1995, 117, 4570.
6. Denmark, S. E.; Chen, C.-T. Tetrahedron Lett. 1994, 35, 4327.
7. All new compounds gave satisfactory spectroscopic and elemental analyses.
8. (a) Olah, G. A.; Liang, G. J. Org. Chem. 1975, 40, 2108.
9. 3-mediated aldol addition completely took over (see ref. 2).
10. 3 (10 mL) or pH 7 buffer was added and the reaction mixture was warmed to room temperature. After usual workup, the crude yellowish oil was purified by column chromatography (EtOAc/hexane, 1/4) on silica gel to afford 131.2 mg (55 %) of β-hydroxy ester 4b as a mixture of anti/syn (86/14) isomers along with 4a (45%, anti/syn = <5/>95).
11. Heathcock, C. H.; Davidsen, S. K.; Hug, K. T.; Flippin, L. A. J. Org. Chem. 1986, 51, 3027.
12. 3) solution for 12 hours.
13. Note added in proof: The chiral version of the Mukaiyama aldol addition between benzaldehyde and silyl ketene acetal derived from ethyl acetate showed unsatisfactory but significant enantioselectivity. (t-butylphenyl: 11 %ee (TMS), 6 %ee (TBS); 2,6-dimethoxyphenyl: 22 %ee (TBS)). Chen, C.-T.; Chao, S.-D.; Yen, K.-C.; Chen, C.-H.; Chou, I.-C.; Hon, S.-W. J. Am. Chem. Soc. 1997, 119, 11341.
14. - (3).
15. 3 as Lewis acids, see: Le Roux, C.; Gaspard-Iloughmane, H.; Dubac, J.; Jaud, J.; Vignaux, P. J. Org. Chem. 1993, 58, 1835.
16. 4-mediated aldol reaction: Tomo, Y.; Yamamoto, K. Tetrahedron Lett. 1985, 26, 1061.
17. 2 in the aldol addition, see: Mukaiyama, T.; Kobayashi, S. Chem. Lett. 1987, 491.
18. (a) Olah, G. A.; Heiliger, L.; Li, X.-Y.; Prakash, G. K. S. J. Am. Chem. Soc. 1990, 112, 5991.
19. 2 has been used as an active catalyst in Mukaiyama-type aldol reaction: Iwasama, N.; Mukaiyama, T. Chem. Lett. 1987, 463.