Catalytic enantioselective protonation of samarium enolates by a C2-symmetric chiral diol

Tetrahedron Letters

Volumn 37, Issue 16, 1996, Pages 2805-2808

  Nakamura, Yutaka ^a   Takeuchi, Seiji ^a   Ohira, Akiko ^a   Ohgo, Yoshiaki ^a  

^a NIIGATA UNIVERSITY OF PHARMACY AND APPLIED LIFE SCIENCES   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

ALKANOL; DIKETONE; KETONE; PHENOL DERIVATIVE;

ARTICLE; CATALYSIS; CHIRALITY; DRUG SYNTHESIS; REACTION ANALYSIS;

EID: 0029921615     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/0040-4039(96)00434-0     Document Type: Article

References (18)

1. a) Matsumoto, K.; Ohta, H. Chem. Lett. 1989, 1589-1592.
2. b) Matsumoto, K.; Tsutsumi, S.; Ihori, T.; Ohta, H. J. Am. Chem. Soc. 1990, 112, 9614-9619.
3. c) Matsumoto, K.; Ohta, H. Tetrahedron Lett. 1991, 32, 4729-4732.
4. d) Piva, O.; Henin, F.; Muzzart, J.; Pete, J-P. Tetrahedron Lett. 1987, 28, 4825-4828.
5. e) Piva, O.; Pete, J-P. Tetrahedron Lett. 1990, 31, 5157-5160.
6. f) Piva, O.; Mortezaei, R.; Henin, F.; Muzart, J.; Pete, J-P. J. Am. Chem. Soc. 1990, 112, 9263-9272.
7. g) Reymond, J-L.; Janda, K. D.; Lener, R. A. J. Am. Chem. Soc. 1992, 114, 2257-2258.
8. h) Fujii, I.; Lerner, R. A.; Janda, K. D. J. Am. Chem. Soc. 1991, 113, 8528-8529.
9. i) Reymond, J-L.; Jahangiri, G. K.; Staudt, C.; Lerner, R. A. J. Am. Chem. Soc. 1993, 115, 3909-3917.
10. j) Reymond, J-L.; Rever, J-L.; Lerner, R. A. Angew. Chem. Int. Ed. Engl. 1994, 33, 475-477.
11. k) Jahangiri, G. K.; Reymond, J-L. J. Am. Chem. Soc. 1994, 116, 11264-11274.
12. a) Fehr, C.; Stempf, I; Galindo, J. Angew. Chem. Int. Ed. Engl. 1993, 32, 1042-1044.
13. b) Fehr, C.; Stempf, I.; Galindo, J. ibid. 1993, 32, 1044-1046.
14. Yanagisawa, A.; Kikuchi, T.; Watanabe, T.; Kuribayashi, T.; Yamamoto, H. Synlett 1995, 372-374.
15. a) Takeuchi, S.; Miyoshi, N.; Ohgo, Y. Chem. Lett. 1992, 551-554.
16. b) Takeuchi, S.; Ohira, A.; Miyoshi, N.; Mashio, H.; Ohgo, Y. Tetrahedron Asymm. 1994, 5, 1763-1780. Several by-products were obtained through PTLC. Trace amounts of 4-iodobutyl-2,3-dimethyl-3-phenylbutanoate which was formed by a reaction between the ketene and THF, and 2,3-dimethyl-3-phenylbutanoic acid were isolated. Other by-products seem to contain allylated products and oligomers of the ketene, but these have not yet been identified precisely.
17. The difference between the Yanagisawa and Yamamoto system and our reaction conditions to give the maximum enantiomeric excesses may come from stronger co-ordination of the oxygen anion to the samarium ion than to the lithium ion. Thus, higher reaction temperature is required for the protonation of the conjugate base of DHPEX and the samarium enolate, which results in more severe reaction conditions for the selective protonation of the conjugate base. Therefore, longer reaction time and weaker acidity are desired for our reaction system compared to the Yanagisawa and Yamamoto system.
18. 3+ group owing to a change of the co-ordination sphere of the samarium enolate. In the catalytic reaction, trityl alcohoxide anion is formed during the reaction, and it may disturb the co-ordination sphere of the samarium enolate. See Ref. 4b), details will be reported elsewhere.