(1S)-1-[(4R)-2,2-Dimethyl-1,3-dioxolan-4-yl]-2-hydroxyethylammonium Benzoate, A Versatile Building Block for Chiral 2-Aminoalkanols: Concise Synthesis and Application to Nelfinavir, a Potent HIV-Protease Inhibitor

A concise synthesis of a versatile chiral C4 building block for 2-aminoalkanols, (1S)-1-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2-hydroxyethylammo nium benzoate (1a), was described. 1 (1a and its enantiomer 1b) acted as four stereoisomers of optically active 2-amino-1,3,4-butanetriol. The versatility of 1 was demonstrated by its application to the practical synthesis of nelfinavir (2), a potent HIV-protease inhibitor, as well as by the stereospecific synthesis of three diastereomers of 2.