Asymmetric synthesis of erythro-β-hydroxyasparagine

erythro-Hydroxyasparagine (eHyAsn, 1) occurs in a number of naturally occurring peptides and proteins. Previous syntheses have relied on enzyme-catalyzed reactions to produce relevant, optically active intermediates. We report herein a completely chemical synthesis that intercepts Boger’s synthesis of the diastereomer (tHyAsn, 4), utilizing a Sharpless asymmetric aminohydroxylation reaction to introduce the two stereocenters. Boc-HyAsn(OTBS)-OH (10) was coupled effectively with phenylalanine methyl ester using EDC/HOBt.