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Tricky organic problem

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    Have lost the sheet with it on but can remember it:

    Compound X reacts with water, toluene (presumably solvent) and heat to form para-chlorophenol.

    Compound X has the following spectroscopic data:

    C6H6OCl2, so HCl is eliminated in the reaction.
    Contains fused 3 and 5 membered rings.

    IR 1740 - suggests cyclopentanone ring
    1H NMR:
    d ~2.5ish (2H, dd, 15.4, 1.4 Hz) (1) - big geminal coupling indicates adjacent to pi system. Smaller coupling probably pseudo axial-pseudo equatorial
    d ~2ish (2H, dd, 15.4, 4.3 Hz) (2) - big geminal coupling again. Small coupling probably the pseudo axial-pseudoaxial. Smaller than normal axial-axial as not anti to each other.
    d ~1.5ish (2H, dd, 4.3, 1.4 Hz) (3)

    These data fit with having the cyclopropane ring in a pseudoequatorial position relative to the 5M ring.

    13C NMR
    208 (s)
    73 (s)
    Two more peaks which I can't remember the precise chemical shifts. Both were low (alkyl), one doublet and one triplet.

    Propose a structure for X and a mechanism for the reaction.

    I think I've got a structure for X but have no idea for the mechanism.

    Genuinely no idea.
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    I'd agree with your structure - not alot else it could be :p: I'd take a stab at base-induced enolisation, ring opening and Cl- elimination. Then final tautomerisation to the product.
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    (Original post by EierVonSatan)
    I'd agree with your structure - not alot else it could be :p: I'd take a stab at base-induced enolisation, ring opening and Cl- elimination. Then final tautomerisation to the product.
    Hmm. I don't really like water catalysed enolisation! Although could it go via a hydrate or something similar which might increase the acidity of the alpha proton?
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    (Original post by illusionz)
    Hmm. I don't really like water catalysed enolisation! Although could it go via a hydrate or something similar which might increase the acidity of the alpha proton?
    All you need is a tiny fraction and the reaction will funnel through it. There's a very significant driving force for it to occur (release of ring strain, aromaticity) and a nice high energy environment to overcome kinetic barriers.
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    (Original post by EierVonSatan)
    All you need is a tiny fraction and the reaction will funnel through it. There's a very significant driving force for it to occur (release of ring strain, aromaticity) and a nice high energy environment to overcome kinetic barriers.
    Makes sense I guess. Just never come across a mechanism quite like that. Amazing how much simpler things get when you have more than 10 minutes to think about it and aren't under exam pressures!

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