The following reaction confuses me - I don't understand how and why it happened (couldn't figure out the mechanism):

enter image description here

I thought this is some Wolff Kishner sort of reduction, but the reagents don't match (no alkaline medium). I am not sure how hydrazine lead to cyclisation - for starters, I guess it added to the carbonyl oxygen (aldehyde, as it is more reactive) as an ammonia derivative to form a hydrazone. What's next?

  • 1
    $\begingroup$ What's next in a further nucleophilic attack by the NH2 at the other end of the hydrazone on the ketone $\endgroup$
    – Waylander
    Jul 4, 2018 at 15:52
  • $\begingroup$ I did that, what happens then? $\endgroup$ Jul 4, 2018 at 16:04
  • 1
    $\begingroup$ Elimination of water to form the product drawn $\endgroup$
    – Waylander
    Jul 4, 2018 at 16:22
  • $\begingroup$ Could you please add the mechanism as an answer? I'm not able to figure out how dehydration would occur after internal nucleophilic attack by the nitrogen on carbonyl oxygen. Thanks. $\endgroup$ Jul 4, 2018 at 17:23

1 Answer 1


It's essentially just the same reaction once and then over again. The basic medium of the Wolf-Kishner reduction is to remove the hydrazone hydrogen, releasing the $\ce{C=N}$ electrons onto the carbon. In this reaction, the hydrazone instead further reacts with the other carbonyl to form an aromatic 6-membered ring.

step 1

step 2

step 3

step 4

step 5


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.