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I've been away from orgo for a few years but lately someone asked me a question about lactones during a Wolff-Kishner reduction. I understand the basic mechanism of a Wolff-Kishner but I cannot figure out how a lactone gets hydrolyzed. Can anyone help me with that step?

Here is a link to the basic mechanism that mentions lactones.

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This is a general feature of the hydrazine reagent that is employed in Wolff-Kishner reductions. When attacking an ester’s (includes lactone’s) carbonyl function, the generated tetrahedric intermediate can break down to form a hydrazide as shown in the scheme below.

hydrazide formation

The carbonyl function is not reduced but the ester (or lactone) is hydrazinolysed.

One could assume that the displace alcoholate could reattack the carbonyl group to regenerate the ester/lactone. However, apart from hydrazine being much more nucleophilic than alcoholates, the resulting hydrazide is also stabilised much like an amide, and is therefore less reactive.

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