(2R,3R,4R)-N-benzyloxycarbonyl-2-(((S)-valineamidyl)methyl)-3,4-dihydroxypyrrolidine

(2R,3R,4R)-N-benzyloxycarbonyl-2-(((S)-leucineamidyl)methyl)-3,4-dihydroxypyrrolidine

(2R,3R,4R)-N-benzyloxycarbonyl-2-(((S)-phenylalanineamidyl)methyl)-3,4-dihydroxypyrrolidine

(2R,3R,4R)-N-benzyloxycarbonyl-3,4-dihydroxy-2-((((S)-1-methoxy-1-oxo-3-phenylpropan-2-yl)amino)methyl)pyrrolidine

(2R,3R,4R)-N-benzyloxycarbonyl-2-(((S)-aspartic(βtBu)amidyl)methyl)-3,4-dihydroxypyrrolidine