New Asymmetric Route To α-Amino Acid Esters

Developed in 1997 by Nicos A. Petasis of the University of Southern California, the Petasis reaction (shown; R substituents are various organic groups) is a multicomponent condensation of boronic acids with amines and aldehydes. Although that reaction is not catalytic, it has provided a way to make α-amino acids, and medicinal chemists often have relied on it. Now, Sha Lou and Scott E. Schaus of Boston University's Center for Chemical Methodology & Library Development report developing the first asymmetric catalytic version of the Petasis reaction. It uses chiral biphenol catalysts to convert alkenyl boronates, secondary amines, and glyoxylates to chiral α-amino acid esters with good yields and high enantiomeric ratios (J. Am. Chem. Soc., DOI: 10.1021/ja8018934). The advance eliminates the need for stoichiometric chiral starting materials and opens the way to a broader range of products.