(2S)-3-methyl-2-(4-methyl-2,6,7-trioxabicyclo[2.2.2]oct-1-yl)-5-oxo-2,5-dihydro-pyrrole-1-carboxylic acid benzyl ester

(2S,3S)-1-(benzyloxycarbonyl)-3-n-butyl-glutamic acid

(2S,3R,4S)-3-methyl-2-(4-methyl-2,6,7-trioxabicyclo[2.2.2]oct-1-yl)-5-oxo-4-phenylselenenyl-pyrrolidine-1-carboxylic acid benzyl ester