Sulfonamides are widely used in pharmaceutical chemistry and agrochemistry. Sulfonimidamides are aza-analogues of sulfonamides and can also be bioactive. NH-unsubstituted sulfonimidamides are particularly interesting because they can take part in hydrogen bonds and are more hydrophilic than N-functionalized derivatives. Existing synthesis methods often lead to N-functionalized sulfonimidamides, requiring an additional step to obtain unsubstituted derivatives. Alternative approaches can need, for example, highly reactive oxidants.

Carsten Bolm, RWTH Aachen University, Germany, and colleagues have developed a method for the direct synthesis of NH-sulfonimidamides via the copper-catalyzed coupling of primary sulfinamides with secondary amines, using air as the terminal oxidant. The team used a broad range of primary sulfinamides and both cyclic and acyclic amines as substrates. They were reacted using CuBr₂ as the catalyst and toluene as the solvent under air at room temperature.

The desired sulfonimidamides were obtained in generally good yields. The team proposes a mechanism that involves a copper-bound sulfanenitrile as a key intermediate. The reaction shows a good functional group tolerance, uses air as the only oxidant, and requires no pre-functionalized reactants or additives.

• Copper-Catalyzed, Aerobic Synthesis of NH-Sulfonimidamides from Primary Sulfinamides and Secondary Amines,
  Peng Wu, Joachim Demaerel, Deshen Kong, Ding Ma, Carsten Bolm,
  Org. Lett. 2022.
  https://doi.org/10.1021/acs.orglett.2c02804