The preparation of the vinylogue guanidinium salt 10c is described. The reaction of the vinylogue orthocarbonic acid amide derivative 12 with CH2-acidic compounds 14a–s affords the ketene aminals 15a–s. At room temperature the succinimide 19a is deprotonated by 12 to give the vinylogue salt 10e. The bis-ketene aminal 20 is formed in the reaction of 19a with 12 at elevated temperatures. Succinic acid esters 21 do not react cleanly with the orthoamide 12, but mixtures of ketene aminals 23 and bis-ketene aminals 22 are formed. From succinodinitrile (24) and 12 the bis-ketene aminal 25 could be obtained, which is also accessible by the action of the salt 10c with 24 in the presence of sodium hydride.
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