Studies Toward the Synthesis of (−)-Zampanolide: Preparation of N-Acyl Hemiaminal Model Systems

[structure: see text] Synthesis of N-acyl hemiaminal model systems related to the side chain of the antitumor natural product zampanolide is reported. Key steps involve oxidative decarboxylation of N-acyl-alpha-amino acid intermediates, followed by ytterbium triflate mediated solvolysis. Evidence for stabilization of the N-acyl hemiaminal moiety in model compounds by an intramolecular hydrogen-bonding network is described.