An acetoacetic ester synthesis of a ketone proceeds by alkylation of the enolate of the acetoacetic ester…

An acetoacetic ester synthesis of a ketone proceeds by alkylation of the enolate of the acetoacetic ester followed by ester hydrolysis and decarboxylation of the \(\beta\) -ketoacid. Which of the following methyl ketones is difficult to prepare by this method?
  1. \(\mathrm{CH}_{3} \mathrm{\stackrel{\huge \mathrm{O} \atop \large ||}{C}CH}_{2} \mathrm{C}\left(\mathrm{CH}_{3}ight)_{3}\)
  2. \(\mathrm{CH}_{3} \mathrm{\stackrel{\huge \mathrm{O} \atop \large ||}{C}CH}_{2} \mathrm{CH}_{2} \mathrm{Ph}\)
  3. \(\mathrm{CH}_{3} \mathrm{\stackrel{\huge \mathrm{O} \atop \large ||}{C}CH}_{2} \mathrm{CH}_{2} \mathrm{CH}=\mathrm{CH}_{2}\)
  4. \(\mathrm{CH}_{3} \mathrm{\stackrel{\huge \mathrm{O} \atop \large ||}{C}CH}\left(\mathrm{CH}_{2} \mathrm{Ph}ight)_{2}\)

Solution

The alkylation of the enolate is an \(\mathrm{S}_{\mathrm{N}} 2\) reaction, and sterically hindered alkyl groups are difficult to introduce. However, even dialkylation is possible with reactive alkylating agents, as in (d). ~

Asked in: JEE-TOPICTESTS-CHEMISTRY

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