Question

Question: Draw a stepwise mechanism showing how two alkylation products are formed in the following reaction.

Short answer

Answer

Stepwise mechanism:

Step 1

Step 2

Step-by-step solution

Enolate ion formation using LDA

Strong organic bases such as LDA can be used to drive the ketone-enolate equilibrium completely to the enolate side.

The bulky isopropyl groups make LDA non-nucleophilic and useful for deprotonation.

Alkylation product mechanism

The mechanism for alkylation products is given as:

In the first step, the acidic hydrogen is deprotonated by diisopropyl amide giving a resonance stabilized enolate ion.

Formation of resonance stabilized enolate

In the next step, the enolate reacts with methyl bromide, attacking the methyl group and expelling the bromide ion, and forming the alkylated product

Reaction with alkyl halide

Formation of alkylated product