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In the reaction below the ethylene glycol would react with the ketone in the first step turning it into a protecting group. How would the ylide react, as I thought it only reacts with ketones and aldehydes to form alkenes?

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  • $\begingroup$ Phosphorous ylides are good nucleophiles. They react with alkyl halides to give alkylation $\endgroup$
    – Waylander
    Jul 28 at 21:02

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phos ylide always has a resonance form making a positive phosphorus and a Carbanion. Use that carbanion (its a nucleophile same way you do with grignard) to attack the Carbon thats attached the Br (electrophilic carbon with Br leaving group, and cant attack ketone as its protected rn as a ketal).

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    $\begingroup$ It is better to put complete names of chemicals etc. with in your answer, because all of our readers are not chemistry experts. Also, what you means by the phrase 'its protected rn'? And, Grignard is a person's name so its first letter should be upper case. $\endgroup$ Jul 28 at 22:53
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    $\begingroup$ So would this then give a quaternary carbon, or am I looking at this from the wrong way? What would then react with the triphenylphosphine ion? $\endgroup$
    – crisps
    Jul 29 at 2:31
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    $\begingroup$ This does give a quaternary carbon next to the PPh3 group so another carbanion cannot be formed there. This group is stable to the dioxolane hydrolysis conditions, there will be no further reaction. $\endgroup$
    – Waylander
    Jul 29 at 7:05

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