Saturday, September 8, 2007

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 form tertiary amides. In the presence of lithium chloride, the enolates of the corresponding pseudoephedrine amides undergo highly diastereoselective alkylations with a wide range of alkyl halides.

Advantages of using psuedoephedrine as chiral auxiliary,

• Enolate of pseudoephedrine amide undergo efficient and high diastreoselective alkylation with wide variety of alkyl halides.
• High enantiometrically enriched carboxylic acids, alcohols, aldehydes and ketones
• Large scale/ Preocess application ( low cost of auxiliary, crystallinity of starting materials and products, no carcinogenic solvents.)
Ref.: Myers, A.G. et al., J. Am. Chem. Soc., 1997, 119 , 6496

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