Double stereocontrol in α-alkylation of chiral lithium dienolates generated from (E)-α,β-olefinic amides and esters

Chemistry Letters

Volumn , Issue 10, 1998, Pages 1049-1050

  Tomooka, Katsuhiko ^a   Nagasawa, Atsushi ^a   Nakai, Takeshi ^a  

^a TOKYO INSTITUTE OF TECHNOLOGY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0002496685     PISSN: 03667022     EISSN: None     Source Type: Journal    
DOI: 10.1246/cl.1998.1049     Document Type: Article

References (19)

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3. c) D. A. Evans, Aldrichimica Acta, 15, 23 (1982).
4. K. Tomooka, A. Nagasawa, S.-Y. Wei, and T. Nakai, Tetrahedron Lett., 37, 8895 (1996). For similar reactions of the boron dienolate of (E)-2a with α,β-enals, see: K. Tomooka, A. Nagasawa, S.-Y. Wei, and T. Nakai, Tetrahedron Lett., 37, 8899 (1996).
5. K. Tomooka, A. Nagasawa, S.-Y. Wei, and T. Nakai, Tetrahedron Lett., 37, 8895 (1996). For similar reactions of the boron dienolate of (E)-2a with α,β-enals, see: K. Tomooka, A. Nagasawa, S.-Y. Wei, and T. Nakai, Tetrahedron Lett., 37, 8899 (1996).
6. (E)-1a-f were prepared from (E)-2-pentenoyl chloride according to the reported procedures. 1a: W. Oppolzer, J. Blagg, I. Rodriguez, and E. Walther, J. Am. Chem. Soc., 112, 2767 (1990).
7. 1b: J. R. Gage and D. A. Evans, Org. Synth. Coll., VIII, 339 (1993).
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9. 1d: J. d'Angelo and J. Maddaluno, J. Am. Chem. Soc., 108, 8112 (1986).
10. 1e: Y. Kawanami, Y. Ito, T. Kitagawa, Y. Taniguchi, T. Katsuki, and M. Yamaguchi, Tetrahedron Lett., 25, 857 (1984).
11. 1f: D. A. Evans and J. M. Takacs, Tetrahedron Lett., 21, 4233 (1980).
12. R=20.6 min for (E, S)-isomer.
13. The stereochemistry at the α-position was assigned as (S) for 3a, b and 3e, (R) for 3c and 3d, based on the our allylation reaction (ref. 2) and reported results (ref. 3).
14. Note that, the allylation reaction also proceeds in a highly stereoselective manner: A reaction of the dienolate derived from (E)-1e with allyl bromide gave the (Z)-3 (R=allyl) in 99% de, 98% Z.
15. a) E.-P. Krebs, Helv. Chim. Acta, 64, 1023 (1981).
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