Synthesis of highly epimerizable N-protected α-amino aldehydes of high enantiomeric excess

The Dess–Martin periodinane was found to be a superior oxidant for the efficient, epimerization-free synthesis of optically active N-protected α-amino aldehydes from the corresponding N-protected β-amino alcohols. Highly racemization-prone products, including N-Fmoc phenylglycinal and N-trifluoroacetyl α-amino aldehydes, were prepared in ≥95% yield with ≤1% epimerization.