Use of pseudoephedrine as a practical chiral auxiliary for asymmetric synthesis

Citation

Yang, Bryant H. (1997) Use of pseudoephedrine as a practical chiral auxiliary for asymmetric synthesis. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1K2S-P110. https://resolver.caltech.edu/CaltechTHESIS:02202014-095838875

Abstract

The use of pseudoephedrine as a practical chiral auxiliary for asymmetric synthesis is describe. Both enantiomers of pseudoephedrine are inexpensive commodity chemicals 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 a1kylations with a wide range of alkyl halides to afford α-substituted products in high yields. These products can then be transformed in a single operation into highly enantiomerically enriched carboxylic acids, alcohols, and aldehydes. Lithium amidotrihydroborate (LAB) is shown to be a powerful reductant for the selective reduction of tertiary amides in general and pseudoephedrine amides in particular to form primary alcohols.

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