Alkylated pseudoephedrine amides synthesis

Amides bearing chirality at the a-position are available from the chiral pyrrolidinone 13 through iV-acylation, alkylation, and aminolysis. Pseudoephedrine has been developed into a practical chiral auxiliary for the synthesis of a-branched carboxylic acids (and other... 

The series on asymmetric synthesis then concludes with procedures for the preparation of enantiomerically pure products. The asymmetric syntheses of unnatural a-amino acids by the alkylation of pseudoephedrine glycin-amide is nicely exemplified by the preparation of l-ALLYLGLYCINE and N-BOC-i.-ALLYLGLYCINE. One of the advantages of this method is the ready availability of the chiral auxiliary and the mildness of the conditions required for the hydrolysis of the pseudophedrine amide to provide the a-amino acid. Biocatalytic transformations are also gaining importance in asymmetric synthesis as illustrated by the preparation of... 

Before embarking on a discussion of new reactions, it will be useful to describe recently reported examples of the synthetic utility of the reducing capabilities of the LABs. Myers has recently described a practical synthesis of chiral alcohols employing pseudoephedrine as a chiral auxiliary (4). An amide of pseudoephedrine is first deprotonated with LDA and then alkylated with the appropriate alkyl halide to give the substituted amide with 97-99% de. The amide is then reduced to the alcohol with lithium pyrrolidinoborohydride to give... 

---