Question

Question: Treatment of ketone A with LDA followed by CH₃CH₂ did not form the desired alkylation product B. What product was formed instead? Devise a multistep method to convert A to B, a synthetic intermediate used to prepare the anticancer drug tamoxifen (Section 23.8C and the chapter-opening molecule).

Short answer

Answer

The reaction of A with LDA is shown below:

The conversion of A to B is shown below:

Step-by-step solution

Lithium di-isopropyl amide

It abstracts a proton from the carbon, having fewer hydrogen atoms or less hindrance. It is non-nucleophilic but is a strong base.

Steps involved in the reaction

The reaction of A with LDA, THF is shown below

Reaction of A with LDA

The conversion of A to B is shown below:

Conversion of A to B