Amines formamidinium salts

The reaction of amine hydrochlorides with thioxoesters affords amidinium salts (155 equation 91). Formamidinium salts (156 equation 92) with bulky substituents at the nitrogens can be obtained by oxidation of AA A/ -trisubstituted or AA -disubstitut thioureas with peracetic acid. - Byproducts in this reaction can be ureas and thiourea trioxides. -Dimethylaminoacrolein reacts with dimethylamine hydrochloride to give (157 equation 93), the parent compound of the vinylogous amidinium salt series. - From AA -dimethylthiobenzamide and Al-sulfinyldimethylammonium tetrafluoroborate the benzamidin-ium salt (158 equation 94) was prepared. ... 

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 ... 

V,1V,N JV -Tetrasubstituted formamidinium salts as well as bis(dialkylamino)acetonitriles have been reacted with alkali metal amides of secondary amines to give tris(dialkylamino)methanes (534 Scheme... 

Treatment of orthoamide 123 with equimolar amounts of aqueous hydrochloric acid yielded the salt 124 from which 123 can be regenerated by neutralization. NMR indicates that salt 124 and bicyclic formamidinium ion 126 interconvert rapidly at 70°C. This is explained by a conformational change from 124 into 125 which permits elimination of the amine group with stereoelec-tronic control (125 126). Finally, addition of excess hydrochloric acid to orthoamide 123 precipitated the bicyclic dichloride 127. 

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