(R)-1-<1,1-(dimethylethoxycarbonyl)>-4-(2-hydroxy-1-phenylethyl)piperazin-3-one

tert-butyl N-(2-{[(1R)-2-hydroxy-1-phenylethyl]amino}-2-oxoethyl)carbamate

1,1-dimethylethyl (R)-2,5-diaza-7-hydroxy-6-phenylheptanoate

1,1-dimethylethyl (R)-2,5-diaza-9,9,10,10-tetramethyl-8-oxa-6-phenyl-9-silaundecanoate

(R)-1-<1,1-(dimethylethoxycarbonyl)>-4-(4,4,5,5-tetramethyl-1-phenyl-3-oxa-4-sila-hexyl)piperazin-3-one