Petasis boronic acid–Mannich reactions of substituted hydrazines: synthesis of α-hydrazinocarboxylic acids

N-1-(Carbamate protected)-N-2-(alkyl or aryl substituted) hydrazines can serve as amine substrates for the Petasis boronic acid–Mannich reaction, providing a practical synthetic route for the preparation of α-hydrazinocarboxylic acids. The scope and limitations of this method have been examined.