- The generation of iminium ions using chlorosilanes and their reactions with electron rich aromatic heterocycles
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Dichlorodimethylsilane and trichloromethylsilane have been used to generate iminium ions from aminals and aminol ethers derived from secondary alkylamines, including glycine derivatives, in aprotic media which were shown to undergo reactions with electron rich aromatic heterocycles, including furan, to give mono-aminoalkylation products in good yields. Whereas chlorotrimethylsilane has been shown to generate iminium ions from aminol ethers, no evidence was adduced for the involvement of iminium ions using aminals. 2,5-Disubstitution of N-methylpyrrole was the major result in reactions of N-methylpyrrole with aminals in the presence of chlorotrimethylsilane where no build up of hydrogen chloride occurs and where chlorotrimethylsilane can function catalytically. Experimental results, including the use of bis(trimethylsilyl)acetamide as a proton scavenger, and some relative rate data, are presented that allow possible mechanisms to be evaluated.
- Heaney, Harry,Papageorgiou, George,Wilkins, Robert F.
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- The activation of aminals and aminol ethers by sulfur dioxide and their reactions with electron rich aromatic compounds
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Reactions of bis(dialkylamino)methanes and ethoxydialkylaminomethanes with nucleophilic aromatic heterocycles in the presence of sulfur dioxide result in the formation of the expected Mannich bases in good yields. Reactions of phenols are similarly activated by sulfur dioxide which lead to improved regioselectivity: in particular the reactions of 2,5-dimethylphenol result in the formation of 2-dialkylaminomethyl-3,6-dimethylphenol whereas reaction occurs at the I-position using the classical procedures.
- Heaney, Harry,Papageorgiou, George,Wilkins, Robert F.
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p. 13361 - 13372
(2007/10/03)
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