Is there any particular reason why this mechanism is used in the solution manual rather than an acid-catalyzed hydration?

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I was thinking of having the double bond attack a hydronium ion, which would create a carbocation. This would then create a place for water to attack. Finally, the water would be attacked by water to reform hydronium ion.

Why wouldn't this work?

Does this have anything to do with the fused ring?

  • 1
    $\begingroup$ I think ron's answer is correct. Incidentally, another synthetic route avoiding a carbocation might be epoxidation by a peroxyacid (e.g., mCPBA) followed by treatment with a hydride donor (e.g., LAH). Personally, I would rather deal with a pyrophoric substance like LAH over a mercury compound, but you pick your poison either way. $\endgroup$
    – Greg E.
    Jul 14, 2014 at 15:38

1 Answer 1


Acid catalyzed hydration probably would work, but might well be accompanied by other materials derived from the carbocation intermediate, such as rearrangement and elimination products, which would make this route less desirable. The mercuric acetate route does not involve free carbocations, so such side products will not contaminate the desired product.

  • 1
    $\begingroup$ +1, this was my thought as well. Isomerization to spiro[4.5]decan-6-ol seems possible as far as rearrangements go, but I see no reason to suppose it'd be favorable. Elimination to give the tetrasubstituted double bond seems plausible, though. $\endgroup$
    – Greg E.
    Jul 14, 2014 at 15:26
  • $\begingroup$ Yes, the 9,10-octalin would be the concern. $\endgroup$
    – ron
    Jul 14, 2014 at 15:40

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