Ketene aminals amidinium salts

Ketene aminals can be transformed by various electrophilic reagents to amidinium salts, thus mineral acids, alkyl halides, A///-dialkyliminium salts, alkoxymethyleneiminium salts, formamidinium salts, acyl halides, diazonium salts, vinylogous amidinium salts,sulfonyl halides, ketene dichlorides ... 

Ketoketene aminals as well as 3-(methylmercaptothiocarbonyl) ketene aminals can be alkylated at the oxygen or sulfur, respectively, to afford the corresponding amidinium salts (171 equation 97). Ketene aminals, being electron rich compounds, are easily oxidized to yield amidinium salts. In the course of such investigations interesting results were obtained, for example dimerizations or cycliza-tions can occur -as well as formation of simple amidinium salts. By oxidation amidinium salts can be synthesized which are accessible only with difficulty by other meftods, e.g. (172), (173) and (174) (Scheme 22). 

The reaction of a-chloroenamines with primary or secondary amines affords amidinium salts, e.g. (177 equation 100). In most cases not the amidinium salts but their deprotonation products (ketene animals or amidines) have been isolated these reactions have been reviewed. Imino compounds undergo cycloadditions with a-haloenamines in which a-azetidylideneammonium salts (178 equation 101) are formed. " Ynamines are converted to amidinium salts, e.g. (179), (180) and (181) (Scheme... 

Without additional reagents Synthesis of carboxylic acid amides from ketene aminals via amidinium salts... 

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