methyl (2S,3S)-2-((S)-1-acetoxy-2-methylpropyl)-3-hydroxy-5-oxopyrrolidine-2-carboxylate

methyl (2R,3S)-3-(tert-butoxy)-2-((S)-1-hydroxy-2-methylpropyl)-5-methoxy-3,4-dihydro-2H-pyrrole-2-carboxylate

(6S,7R,7aR)-7-(tert-butoxy)-3,3-dimethyl-6-(phenylsulfonyl)tetrahydro-3H,5H-pyrrolo[1,2-c]oxazol-5-one

(S)-1-(4-(tert-butoxymethyl)-2,2-dimethyloxazolidin-3-yl)-2-(phenylsulfonyl)ethan-1-one

(S)-1-(4-(tert-butoxymethyl)-2,2-dimethyloxazolidin-3-yl)-2-diazo-2-(phenylsulfonyl)ethan-1-one