Atorvastatin (Lipitor) is a popular treatment for high

Chapter 20, Problem 20.8

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Atorvastatin (Lipitor) is a popular treatment for high cholesterol. See The Importance of Hydrogen Bonding in Drug-Receptor Interactions in Chapter 10 for more information about atorvastatin. One synthesis of atorvastatin involves the following enolate reaction. Draw the predominant product of this reaction, which gives an overall yield of 90%. 1. 2 Eq. LDA, MgBr2, 78C 2. 3. H2O O O HO O N F H NH O There are a couple of noteworthy aspects to this reaction. First, MgBr2 is added to exchange with Li and make Mg enolates. This is helpful for controlling stereochemistry. Notice that the starting material is chiral and a single enantiomer is used. The product of this reaction is a 97:3 (94% ee) mixture of two enantiomers, not a racemic mixture. You dont 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 using a single enantiomer of a chiral starting material can save time and resources in the large-scale synthesis of chiral drugs.