Evans Auxiliary Structure

Evans aldol reaction: A stereoselective two-step reaction

Introduction

The Evans aldol reaction is a stereoselective two-step reaction between an aldehyde and an oxazolidinone chiral auxiliary. This reaction is used to form new carbon-carbon bonds with high levels of enantioselectivity. The Evans aldol reaction is named after its inventor, David A. Evans.

Mechanism

The Evans aldol reaction proceeds via a two-step mechanism. In the first step, the aldehyde and the oxazolidinone chiral auxiliary react to form a chiral enolate. In the second step, the enolate reacts with an electrophile to form the aldol product. The stereoselectivity of the Evans aldol reaction is due to the chiral environment created by the oxazolidinone chiral auxiliary. This environment directs the approach of the electrophile to the enolate, resulting in the formation of the desired enantiomer.

Applications

The Evans aldol reaction is a powerful tool for the synthesis of chiral compounds. This reaction has been used to synthesize a wide variety of natural products and pharmaceuticals.

Conclusion

The Evans aldol reaction is a versatile and stereoselective reaction that is used to form new carbon-carbon bonds. This reaction is a powerful tool for the synthesis of chiral compounds and has been used to synthesize a wide variety of natural products and pharmaceuticals.