Synthesis of Hydroxamic Esters via Alkoxyaminocarbonylation of β-Dicarbonyl Compounds

N-t-Butoxycarbonyl-O-sulfonyl-substituted hydroxylamines react with soft enolates to yield O-t-butoxycarbonylamino derivatives rather than the expected Boc-protected amino acids. The reaction is limited to enolates of β-dicarbonyl compounds. Decarboxylation of the resultant tricarbonyl compound affords malonyl α-alkyl O-t-butoxycarbonylamino derivatives.