Myers Asymmetric Alkylation

Psuedoephedrine is a chiral auxiliary used for the synthesis of enantiomerically enriched carboxylic acid, aldehyde, alcohol and ketones.

Both enantiomers of pseudoephedrine are inexpensive and can be N-acylated in high yields to generate its tertiary amides. In the presence of lithium chloride, the enolates of the corresponding pseudoephedrine amides undergo diastereoselective alkylations with a wide range of alkyl halides.

Advantages of using pseudoephedrine as chiral auxiliary,

• Enolate of pseudoephedrine amide undergoes efficient and high diastereoselective alkylation with a wide variety of alkyl halides,

• High enantiomerically enriched carboxylic acids, alcohols, aldehydes, and ketones, and

• Large scale/ Preocess application ( low cost of the auxiliary, the crystallinity of starting materials and products, no requirement of carcinogenic solvents.) 

Ref: Myers, A.G. et al., J. Am. Chem. Soc., 1997, 119, 6496.