Asymmetric allenylation of aliphatic aldehydes catalyzed by a chiral formamide

Tetrahedron Asymmetry

Volumn 9, Issue 16, 1998, Pages 2889-2894

  Iseki, Katsuhiko ^a   Kuroki, Yoshichika ^a   Kobayashi, Yoshiro ^a  

^a DAIKIN INDUSTRIES LTD   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

ALDEHYDE DERIVATIVE; ALIPHATIC COMPOUND; FORMAMIDE DERIVATIVE; HEMPA;

ARTICLE; CATALYSIS; CHIRALITY; ENANTIOMER; GAS CHROMATOGRAPHY; HIGH PERFORMANCE LIQUID CHROMATOGRAPHY; PRIORITY JOURNAL; RACEMIC MIXTURE; REACTION ANALYSIS; STEREOCHEMISTRY; STRUCTURE ACTIVITY RELATION; SYNTHESIS;

EID: 0032555625     PISSN: 09574166     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0957-4166(98)00290-0     Document Type: Article

References (17)

1. For enantioselective allenylation using a stoichiometric amount of chiral ligands, see: (a) Boldrini, G. P.; Lodi, L.; Tagliavini, E.; Tarasco, C.; Trombini, C.; Umani-Ronchi, A. J. Org. Chem. 1987, 52, 5447-5452. (b) Corey, E. J.; Yu, C.-M.; Lee, D.-H. J. Am. Chem. Soc. 1990, 112, 878-879.
2. For enantioselective allenylation using a stoichiometric amount of chiral ligands, see: (a) Boldrini, G. P.; Lodi, L.; Tagliavini, E.; Tarasco, C.; Trombini, C.; Umani-Ronchi, A. J. Org. Chem. 1987, 52, 5447-5452. (b) Corey, E. J.; Yu, C.-M.; Lee, D.-H. J. Am. Chem. Soc. 1990, 112, 878-879.
3. (a) Kobayashi, S.; Nishio, K. Tetrahedron Lett. 1993, 34, 3453-3456;
4. (b) Kobayashi, S.; Nishio, K. Synthesis 1994, 457-459;
5. (c) Kobayashi, S.; Nishio, K. J. Org. Chem. 1994, 59, 6620-6628;
6. (d) Wang, Z.; Wang, D.; Sui, X. J. Chem. Soc., Chem. Commun. 1996, 2261-2262.
7. Kobayashi, S.; Nishio, K. J. Am. Chem. Soc. 1995, 117, 6392-6393.
8. Iseki, K.; Mizuno, S.; Kuroki, Y.; Kobayashi, Y. Tetrahedron Lett. 1998, 39, 2767-2770.
9. 2O at room temperature for 16 h generated 3 selectively (3:4=86:14); see Ref. 3. However, the distillation (55-58°C/85 torr) from the reaction mixture caused the isomerization between 3 and 4 (3:4=75:25).
10. D -10.2 (c 2.1, benzene).
11. Kobayashi and Nishio have shown that 3 and 4 react with aldehydes in DMF to afford 5 and 6, respectively; see Ref. 3.
12. The reason why HMPA improves the enantioselectivity remains unclear. Both HMPA and 1 may coordinate with 3 to generate a hexavalent silicate.
13. The allenylation of 2e using 40 mol% of 1 and 200 mol% of HMPA in dichloromethane at -78°C for 7 days gave 5e in 74% yield with 28% ee (5e:6e=99:1). Acetone provides higher enantiomeric excesses than dichloromethane in the allenylation of straight-chain aldehydes.
14. 4).
15. Although HMPA itself catalyzes the allenylation of aromatic aldehydes at -78°C, 1 is not effective in terms of enantio selectivity even in the absence of HMPA; see Ref. 4.
16. The present allenylation is very sluggish at -78°C. Elevating the temperature improves the reaction rate but dramatically suppresses the enantio selectivity; the allenylation of 2a in the presence of 1 (40 mol%) and HMPA (200 mol%) was carried out at -40°C for 7 days to afford (S)-5a (5a:6a=91:9) in 84% yield with 19% e.e.
17. Krimen, L. I. Organic Synthesis; John Wiley: New York, 1988; Collect. Vol. 6, pp. 8-9.