Transfer of alkoxycarbonyl from alkyl imidazolium-2-carboxylates to benzyl alcohol, a cyclohexanone enamine and diethylamine
Abstract
Alkylimidazole-2-carboxylates may be alkylated with methyl triflate to give the corresponding N-methylimidazolium salts. These salts react with benzyl alcohol in the presence of 1,4-diazabicyclo[2.2.2]octane, with 1-(pyrrolidin-1-yl)cyclohexene and with diethylamine to give benzyl alkyl carbonates, an enamino ester and a urethane respectively; in one case a tetrahedral intermediate is observed. The corresponding phenyl ester was consumed without attack by benzyl alcohol at the carbonyl group. A 2-cyanoimidazolium salt underwent similar ill-defined consumption whereas a 2-dimethylaminocarbonyl derivative remained unchanged. 2-Methylsulfonylimidazolium salts suffered attack by benzyl alcohol at the ring C-2.
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