Question

Column 1: Name and formula of compound Column

2: Name of the reaction. Column 3:

Major product of reaction.

The only correct combination in which enolate is formed:

• A. (III) (ii) (S)
• B. (IV) (ii) (S)
• C. (IV) (ii) (R)
• D. (IV) (iii) (P)

Answer 1

The correct option is B

(IV) (ii) (S)

Let us briefly look at the initial step - the enolate formation - during the base-catalyzed version of aldol condensation:

This enolate is the nucleophile that attacks the electron-loving or electrophilic carbonyl carbon of un-enolized acetaldehyde. Eventually, we get to the $beta$-hydroxy aldelyde, which then undergies $E_{1}cb$ to give the $\alpha -\beta$ unsaturated aldehyde.