"Contra-Michael" addition of alkyllithiums to silicon- and phenyl-substituted α,β-unsaturated amides in the presence of t-BuOK

Chemistry Letters

Volumn 36, Issue 1, 2007, Pages 54-55

  Hinago, Tomoko ^a   Teshima, Nana ^a   Kenmoku, Satoko ^a   Kamata, Tiyako ^a   Terauchi, Nahoko ^a   Chiba, Nao ^a   Satoh, Chikako ^a   Nakamura, Aya ^a   Asaoka, Mono ^a  

^a JAPAN WOMEN'S UNIVERSITY   (Japan)

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[No Author keywords available]

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EID: 34247236222     PISSN: 03667022     EISSN: None     Source Type: Journal    
DOI: 10.1246/cl.2007.54     Document Type: Article

References (27)

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15. When N-methyl-3-(dimethylphenylsilyl)acrylamide was used in place of 1a, sec-BuLi and t-BuLi were reacted in THF at -78°C for 3 h to afford the corresponding contra-Michael adducts exclusively (50 and 52% yield), however, only the Michael adduct (69% yield) was obtained by the reaction with n-BuLi under the same reaction conditions. In the case of N-methyl-3-(fert-butyldimethylsilyl)acrylamide, the reaction with n-BuLi, sec-BuLi, and t-BuL was sluggish under the same reaction conditions. Addition of TMEDA was necessary for reasonable reaction rate. The Michael adduct (58% yield) was obtained with n-BuLi and the contra-Michel adducts (36 and 66% yields) were obtained with sec-BuLi and r-BuLi in THF in the presence of TMEDA (3 equiv.) at -78°C for 3 h.
16. The combination of n-BuLi with t-BuOK is known as Schlosser's super-base. For Schlosser's super-base and related super-bases, see: M. Schlosser, S. Strunk, Tetrahedron Lett. 1984, 25, 741;
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26. 3): δ 0.04 (s, 9H), 0.71 (dd, 7 = 6.2 and 14.5 Hz, 1H), 0.88 (t, J = 7.0 Hz, 3H), 0.96 (dd, J = 8.7 and 14.5 Hz, 1H), 1.19-1.63 (m, 6H), 2.10 (m, 1H), 2.81 (d, J = 5.0Hz, 3H), 5.59 (brs, 1H). The authentic samples of the Michael and the contra-Michael adducts were prepared as follows.
27. The use of Grignard reagents in place of RLi was also examined but the results were not fruitful; when n-BuMgCl was allowed to react with la in the presence or in the absence of t-BuOK in THF at room temperature, only a trace amount of the corresponding 1,4-adduct was obtained together with a large amount of the starting material.