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methyl 3‐oxobutanoate

I presume the best enol form would have a double bond between the two $\ce{C=O}$ so they're conjugated, but I'm not sure how the resonance would play out.

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The enol forms of beta-diketones and beta -ketoesters are stabilized by intramolecular hydrogen bonds in its enolic form. Enol structure with greater conjugation is more stable and amajor enol.

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update :

In organic chemistry terms, conjugation is used to describe the situation that occurs when π systems (e.g. double bonds) are "linked together". A conjugated system requires that there is a continuous array of "p" orbitals that can align to produce a π bonding overlap along the whole system.If a position in the chain does not provide a "p" orbital or if geometry prevents the correct alignment, then the conjugation is interrupted (broken) and therefore lost at that point. Due to extra π bonding interactions between the adjacent π systems there is an overall stabilization of the system .This is referred to as the delocalisation energy or the resonance energy or conjugation energy

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source:

http://www.chem.ucalgary.ca/courses/350/Carey5th/Ch10/ch10-1-1.html

According to MO theory,1,3-butadiene ,comprised of four overlapping p orbitals are mathematically combined to produce four molecular orbitals.As seen in figure , the four π electrons of a conjugated diene occupy the two lowest energy MOs (the bonding MOs).Specifically, the two electrons that occupy ψ1 are delocalized over four carbon atoms. This delocalization accounts for the observed stabilization energy .

enter image description here source : Organic chemistry ,David R. Klein.page no.773

ref :Advanced Organic ,Chemistry FIFTH EDITION ,Part A: Structure and Mechanisms FRANCIS A. CAREY and RICHARD J. SUNDBERG

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  • $\begingroup$ Based on abrupt paragraphs with numerous new lines and wrong Unicode characters (e.g. Eszett in place of beta) the answer looks copy-pasted from a poorly OCRed book (the ref you mentioned?). If you are quoting a third-party source, please use corresponding markup (> ...) and do at least minimal corrections to the text to make it more readable/editable; also use proper bibliography referencing with page numbers. $\endgroup$ – andselisk May 10 at 14:42
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    $\begingroup$ @andselisk i have reformatted .Thankyou. $\endgroup$ – Chakravarthy Kalyan May 10 at 15:06
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    $\begingroup$ Ehhm, I see you removed a lot, but it's still not clear 1. what is a quotation and what is your work; 2. what page number(s) were used. Also, the formatting is still lacking proper spacing here and there, plus there is a bunch of links for the images at the end that are not used elsewhere. $\endgroup$ – andselisk May 10 at 15:12

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