The most predominant product that gives an overall yield of 90 % for the given reaction has to be drawn. Concept Introduction: Carbonyl compound when treated with LDA (Lithium Diisopropylamide) undergoes deprotonation at the α -carbon to form enolate. The enolate formed is resonance stabilized as the negative charge will be spread over other atoms too. The resonance stabilized intermediate undergoes reaction with other molecule of carbonyl (same or different) to form the respective products. If LDA is used as a base the less substituted α carbon is deprotonated due to steric hindrance. Deprotonation of α carbon to form enolate Nucleophilic attack of enolate S N 2 reaction with alkyl halide

Question

Atorvastatin (Lipitor) is a popular treatment for high cholesterol. See "The Importance of Hydrogen Bonding in Drug-Receptor Interactions" One synthesis of atorvastatin involves the following enolate reaction. Draw the predominant product of this reaction, which gives an overall yield of 90%. Но 1. 2 Equiv. LDA, MgBr, -78°C NH 3. H,O There are a couple of noteworthy aspects to this reaction. First, MgBr, is added to ex- change with Li and make Mg enolates. This is helpful for controlling stereochemistry. Notice that the starting material is chiral and that a single enantiomer is used. The prod- uct of this reaction is a 97:3 (94% ee) mixture of two enantiomers, not a racemic mix- ture. You don't have to be able to deduce which enantiomer is the predominant product, but be aware that being able to control the stereochemical outcome of a reaction by us- ing a single enantiomer of a chiral starting material can save time and resources in the large-scale synthesis of chiral drugs.

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Question

Chapter 19, Problem 19.80P

Interpretation Introduction

Interpretation:

The most predominant product that gives an overall yield of 90% for the given reaction has to be drawn.

Concept Introduction:

Carbonyl compound when treated with LDA (Lithium Diisopropylamide) undergoes deprotonation at the α-carbon to form enolate. The enolate formed is resonance stabilized as the negative charge will be spread over other atoms too. The resonance stabilized intermediate undergoes reaction with other molecule of carbonyl (same or different) to form the respective products. If LDA is used as a base the less substituted α carbon is deprotonated due to steric hindrance.

Deprotonation of α carbon to form enolate

Nucleophilic attack of enolate

S_N2 reaction with alkyl halide

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