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I'm pretty sure the last step in there is just something to throw us off. From what I understand, the first step will give us a Grignard, which will attack the carbonyl in formaldehyde to give us a primary alcohol, and the workup is just to neutralize any remaining Grignard and of course protonate the oxide ion that was just formed. I don't see any possibility of an intramolecular attack either ......

The H2/Pt step looks like a serious red herring from here; I know it doesn't touch the phenyl substituent. And there are no other pi bonds in this system for me to even consider. So is the last step just something to throw me off?

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    $\begingroup$ Is a beta-alkoxy grignard stable at all? $\endgroup$ – Abel Friedman Oct 27 '14 at 3:15
  • $\begingroup$ For the last step, your textbook should set you on the right track, just look up the table of functional groups reduced by catalytic hydrogenation. $\endgroup$ – Abel Friedman Oct 27 '14 at 3:21
  • $\begingroup$ It reacts with formaldehyde. $\endgroup$ – Dissenter Oct 27 '14 at 3:21
  • $\begingroup$ But there are no PI bonds to reduce. $\endgroup$ – Dissenter Oct 27 '14 at 3:23
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    $\begingroup$ The rate of reduction of benzyl ethers is faster than that of the double bond. $\endgroup$ – Abel Friedman Oct 27 '14 at 3:28

The selective debenzylation of benzyl ethers can be carried out under very mild conditions, leaving other functional groups intact. Commonly carried out under H2 using a heterogeneous catalyst such as Pd/C or Raney Ni, Pt can also be used. Solvent choice is critical, and reactions times are longer, but it is still effective.

I don't like red herrings.

  • $\begingroup$ Looks like the product is ethylene glycol! $\endgroup$ – Dissenter Oct 27 '14 at 16:11

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