Catalysis Letters, Vol.109, No.1-2, 55-60, 2006
A reaction of thioamides with zinc ammoniates leading to simple amidines. Discovery of a new zwitterionic monomethylamidine
The reacion of thioamides with the R1R2N-ZnCl ammoniates leads to N-mono-, N,N'-di-, N,N-disubstituted, and unsubstituted amidines with high concentrations of amines in absolute ethanol. The efficient direct formation of the N,N'-dimethylamidine can be explained by a greater reactivity of methylamine compared with dimethylamine. Discovery of a new zwitterion (induced by a carbonyl oxygen) suggests that the stabilization in the thymine N-methylamidine is too slight to prevent the subsequent reaction with methylamine.