Q9. - Organic Chemistry

Question

Question: What enolate is formed when each ketone is treated with LDA in THF solution? What enolate is formed when these same ketones are treated with  NaOCH₃ in CH₃OH  solution?

Step-by-Step Solution

Answer

Answer

 

The enolates formed when each ketone is treated with LDA in a THF solution are as follows. 

 

The enolates formed when the same ketones are treated with the   NaOCH₃ in CH₃OH solution are as follows.

Step 1: Base

A base is a compound that can readily accept protons from the other compounds, either from a less hindered site or from the most hindered site, depending on its bulkiness.

Step 2: Stereoselectivity of the base

LDA is a strong and bulky base that abstracts protons from the least hindered site.

                                 Least hindered site in a

                               Least hindered site in b

                                Least hindered site in c

Sodium ethoxide is a strong and non-bulky base that abstracts protons from the hindered site.

                                            Enolization in a

                                         Enolization in b

                                          Enolization in c