Studies toward the synthesis of (-)-zampanolide:: Preparation of N-acyl hemiaminal model systems

[GRAPHICS] 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 trif late mediated solvolysis. Evidence for stabilization of the N-acyl hemiaminal moiety in model compounds by an intramolecular hydrogen-bonding network is described.