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Synthesis 2013; 45(1): 101-105
DOI: 10.1055/s-0032-1317707
DOI: 10.1055/s-0032-1317707
paper
The First Practical Additive-Free 1,4-Conjugated Alkylation of Fluoroalkylated Electron-Deficient Olefins with Various Organozinc Reagents
Weitere Informationen
Publikationsverlauf
Received: 30. September 2012
Accepted after revision: 08. November 2012
Publikationsdatum:
27. November 2012 (online)
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Abstract
1,4-Conjugated alkylation of fluoroalkylated olefins with organozinc reagents, such as RZnI and R2Zn, was conducted smoothly to give the corresponding products in moderate yields without the use of either transition metals or Lewis acids. This reaction protocol allows not only a wide range of alkyl groups but also electron-withdrawing groups to be incorporated as 1,4-conjugated adducts.
Key words
1,4-conjugated alkylation - organozinc reagents - trifluoromethyl - electron-deficient olefinSupporting Information
- for this article is available online at http://www.thieme-connect.com/ejournals/toc/synthesis.
- Supporting Information
-
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- 8 The alkylzinc halides, RZnI, were prepared according to the reported procedure; see ref. 4b.
- 9 The prepared dialkylzinc reagents were used without the removal of LiCl. For the detailed preparation procedure, see the experimental section.
- 10 The lithium zincate, (n-Bu)3ZnLi, was prepared by mixing 3 equiv of n-BuLi (1.6 M hexane solution) and 1 equiv of ZnCl2 (1.0 M, Et2O solution) at 0 °C for 30 min.
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- 12 The control experiments were conducted as follows. The 1,4-conjugated additions to (E)-1-phenylbut-2-en-1-one or chalcone with Et2Zn were attempted under the same conditions as given in Table 1, entry 2; however, a quantitative amount of the starting alkene was recovered in both cases (methods A and B).
For selected reviews on asymmetric 1,4-conjugate addition, see:
General reviews on organozinc reagents:
For recent studies on organozinc reagents, see:
For comprehensive reviews on diorganozinc reagents, see: