SN2 Reaction at the Amide Nitrogen Center Enables Hydrazide Synthesis.

Nucleophilic substitutions are fundamentally important transformations in synthetic organic chemistry. Despite the substantial advances in bimolecular nucleophilic substitutions (SN2) at saturated carbon centers, analogous SN2 reaction at the amide nitrogen atom remains extremely limited. Here we report an SN2 substitution method at the amide nitrogen atom with amine nucleophiles for nitrogen–nitrogen (N−N) bond formation that leads to a novel strategy toward biologically and medicinally important hydrazide derivatives. We found the use of sulfonate‐leaving groups at the amide nitrogen atom played a pivotal role in the reaction. This new N−N coupling reaction allows the use of O‐tosyl hydroxamates as electrophiles and readily available amines, including acyclic aliphatic amines and saturated N‐heterocycles as nucleophiles. The reaction features mild conditions, broad substrate scope (>80 examples), excellent functional group tolerability, and scalability. The method is applicable to late‐stage modification of various approved drug molecules, thus enabling complex hydrazide scaffold synthesis. [ABSTRACT FROM AUTHOR]