129378-60-5

Structural probes used to help elucidate mechanistic information of the organocatalyzed asymmetric ketimine hydrosilylation have revealed a new catalyst with unprecedented catalytic activity, maintaining adequate performance at 0.01 mol% loading. A new ‘dual activation’ model has been proposed that relies on the presence of both a Lewis basic and Br?nsted acidic site within the catalyst architecture.

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-diazabicyclooctane, 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.

Various substituents have been examined as possible 2-protecting groups against organolithium reagents in the syntheses of imidazoles on the basis of the ease of decarboxylation of imidazole-2-carboxylic acids and cleavage of the C(2)-Si bond.The tertiary