What is the mechanisms of this reaction? How feasible is this reaction? Can it happen under relatively mild conditions if it is intermolecular?

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    $\begingroup$ It's actually a hydrazine that adds to the nitro group. Usually one wouldn't bother to isolate the nitrosubstituted phenyl hydrazine and instead react 2-nitrochlorobenze with aqueous hydrazine under alkaline conditions. $\endgroup$ Mar 2, 2015 at 14:22
  • $\begingroup$ That would just make a nucleophilic aromatic substitution. $\endgroup$
    – EJC
    Mar 2, 2015 at 15:20
  • $\begingroup$ Exactly - for the first step. But would it stop there or rather continue to furnish HOBt? $\endgroup$ Mar 2, 2015 at 15:24
  • $\begingroup$ Okay, thanks for the info, but I am far more interested in the mechanism of the attached reaction. $\endgroup$
    – EJC
    Mar 2, 2015 at 18:23

1 Answer 1


A reasonable mechanism for the transformation is shown below. Since this is under basic conditions, I've written a mechanism that avoids cationic intermediates. Deprotonating the hydrazine gives a very nucleophilic nitrogen that can attack the nitro group. Proton transfer gives a nitrogen anion, which can kick out hydroxide. Two additional proton transfer steps lead to the product, HOBt.

Proposed mechanism

A SciFinder search didn't reveal any examples of the intermolecular variant of this reaction, although I didn't find this exact intramolecular reaction either.


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