Q67. - Organic Chemistry

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).

Step-by-Step Solution

Answer

Answer

 The reaction of A with LDA is shown below:

The conversion of A to B is shown below:

Step 1: 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.

Step 2: 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