1-[N-(9-fluorenylmethyloxycarbonyl)-(1S)-1-amino-2-cyclohexyl-2-oxoethyl]-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane

[(1S,2R)-2-Cyclohexyl-2-hydroxy-1-(4-methyl-2,6,7-trioxa-bicyclo[2.2.2]oct-1-yl)-ethyl]-carbamic acid 9H-fluoren-9-ylmethyl ester

[(1S,2S)-2-Cyclohexyl-2-hydroxy-1-(4-methyl-2,6,7-trioxa-bicyclo[2.2.2]oct-1-yl)-ethyl]-carbamic acid 9H-fluoren-9-ylmethyl ester