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Synlett 2010(3): 379-382  
DOI: 10.1055/s-0029-1219195
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Silicon Tetrachloride Catalyzed Aza-Michael Addition of Amines to Conjugated Alkenes under Solvent-Free Conditions

Najmedin Azizi*a, Roya Baghib, Hossein Ghafurib, Mohammad Bolourtchiana, Mohammad Hashemib
a Chemistry and Chemical Engineering Research Center of Iran, P.O. Box 14335-186, Tehran, Iran
Fax: +98(21)44580762; e-Mail: azizi@ccerci.ac.ir;
b Department of Chemistry, Sharif University of Technology, P. O. Box 11365-9516, Tehran, Iran
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Publication History

Received 16 September 2009
Publication Date:
14 January 2010 (online)

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Abstract

The efficient and very simple conjugate addition of aromatic and aliphatic amines to α,β-unsaturated carbonyl compounds under solvent-free conditions in the presence of catalytic amount of silicon tetrachloride is reported. The reaction of aryl and alkyl amines with different Michael acceptors gave the corresponding Michael adducts with simple catalyst and good to excellent yields.

Key words

aromatic amine - conjugate addition - silicon tetrachloride - β-aminocarbonyl compounds

9

To the mixture of amine (5 mmol) and Michael acceptor (5.2 mmol) under argon, SiCl4 (2 mol%) was added at 0 ˚C, and the mixture was warmed to 60 ˚C and stirred for 1-4 h until the disappearance of the starting amine as indicated by TLC or GC. When the reaction was complete, EtOAc (10 mL) and H2O (10 mL) was added, the organic phase was separated, and dried over Na2SO4. The solvent was removed under reduced pressure, and in most cases, pure product was obtained. If needed, the residue was purified by silica gel column chromatography (hexane-EtOAc). All materials had analytical data in good agreement with data in the literature.