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I am studying drug synthesis, and I found some examples that uses $\ce{H_2}$ and Pd/C or Pd/$\ce{BaSO_4}$ as catalytic hydrogenation reagents for reduction of alcohol or halide in benzylic position. But I have never heard this situation in organic chemistry textbook, and also I have tried search about it but I couldn't found generalized explanation. Is it unusual case of catalytic hydrogenation? Below are the examples.

Synthesis of Zolpidem

In the synthesis of Zolpidem, chloro group is reduced by $\ce{H_2}$ and Pd/$\ce{BaSO_4}$.

Synthesis of Methamphetamine

In the synthesis of Methamphetamine, hydroxyl group is reduced by $\ce{H_2}$ and Pd/C or Pd/$\ce{BaSO_4}$. Also, bromo group is reduced by $\ce{H_2}$ and Pd/$\ce{BaSO_4}$.

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    $\begingroup$ Hydrogenation is a standard method of removing benzyl ether protecting groups so there is ample precedent of cleaving O-Bn bonds whether ethers or alcohols. The stability of both the benzyl cation and radical facilitate this. $\endgroup$
    – Waylander
    Commented Oct 31, 2023 at 11:07
  • $\begingroup$ "Unusual" is a function of experience. $\endgroup$
    – user55119
    Commented Oct 31, 2023 at 21:03
  • $\begingroup$ This recent article explains Zolpidem synthesis, which does not use $\ce{H2/Pd/BaSO4}$ after $\ce{PBr}$ reaction with allyl $\ce{OH}$ group as described in your methamphetamine synthesis route. There might be a mistake somewhere. $\endgroup$
    – Mathew Mahindaratne
    Commented Nov 3, 2023 at 7:44

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