Use of pseudoephedrine as a practical chiral auxiliary for asymmetric synthesis

pseudoephedrine

Yang, Bryant H. ; Myers, Andrew G.

University:California Institute of Technology

Department:Chemistry and Chemical Engineering

关键词: pseudoephedrine;   

Others  :  https://thesis.library.caltech.edu/8089/1/Yang-bh-1997.pdf

美国|英语

来源: Caltech THESIS

【 摘 要 】

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.