Isoprene-catalysed lithiation: deprotection and functionalisation of imidazole derivatives

The isoprene-catalysed lithiation of different 1-substituted imidazoles (1) (such as trityl, allyl, benzyl, vinyl, N,N-dimethylsulfamoyl, para-toluenesulfonyl, tert-butoxycarbonyl, acetyl, trimethylsilyl, tert-butyldimethylsilyl derivatives) leads to the cleavage of the protecting group producing 1H-imidazole. The use of 1-(diethoxymethyl)imidazole (3) in the same lithiation reaction allows the preparation of the corresponding 2-lithio intermediate, which by reacting with different electrophiles leads to 2-functionalised imidazoles 4.