Peptide Inhibitors of Aspartic Proteinases with Hydroxyethylene Isostere Replacement of Peptide Bond. I. Preparation of Four Diastereoisomeric (2R or 2S,4R or 4S,5S)-2-Benzyl-5-[(tert-butoxycarbonyl)amino]-4-hydroxy-6-phenylhexanoic Acids
Peptide Inhibitors of Aspartic Proteinases with Hydroxyethylene Isostere Replacement of Peptide Bond. I. Preparation of Four Diastereoisomeric (2R or 2S,4R or 4S,5S)-2-Benzyl-5-[(tert-butoxycarbonyl)amino]-4-hydroxy-6-phenylhexanoic Acids