Two novel syntheses of a key 4-aminopyrazole synthetic building block are described.
Both routes avoid the potentially explosive precursors that were used in the previously
patented route. A salt of a vinamidinium cation previously used in 5-aminopyrimidine
synthesis was condensed with a protected hydrazine salt leading to a 4-aminopyrazole.
Buchwald-type amination coupling has also been shown to yield the same compound.
heterocycles - pyrazoles - condensation - vinamidinium - Buchwald coupling
