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Sourav posted an Question
September 12, 2020 • 00:56 am 30 points
  • IIT JAM
  • Chemistry (CY)

Plz explain

2 Answer(s) Answer Now
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  • comment-profile-img>
    Boddu rama krishna Best Answer

    c

    cropped4941998834529463438.jpg
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    why ylide attack on that ketone?

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    conjugate ketone less reactive than isolated ketone

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    what about option d

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    option D is Cis alkene. if ylide wittig is non stabilized resultant product is cis alkene...

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    ok if it is stablized than trans product will be formed?

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    yes sourav..

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    what is it regioselectivity not stereo

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    particulary one region it is attacked . here two keto groups are present but wittig reagent attack one keto (isolated) group only..

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    but sir c alkene is cis na?

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    it is trans...H and Me groups oppt side..

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    high priority groups are opposite side

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    Priyanshu kumar best-answer

    see this similar mechanism

    cropped1705055975327219917.jpg
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    why that ketone more deficient?

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    based on ketone reactivity sourav...ylide attacks here

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    conjugated ketone are more stable so less reactive...so ylide attack doesn't takes place here

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    what about option d?

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    https://chemistry.stackexchange.com/questions/5313/why-does-the-unstabilised-wittig-reaction-selectively-form-cis-alkenes check this

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    sir ye regio kyun hai?

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    yha other possible atoms pe bhi reaction ho sakte hai but ylide attacks ek particular atom pe hue...so regioselective hue

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