(+/-)-4-deoxy-1,4-bis(ethoxycarbonylamino)-2,3-O-isopropylidene-1-O-methyl-lyxitol

ethyl (1SR,5RS,6SR,8RS)-6-ethoxycarbonylamino-8-hydroxymethyl-3,3-dimethyl-2,4-dioxa-7-azabicyclo<3.3.0>octane-7-carboxylate

(1RS,2SR,6RS,7SR)-7-ethoxycarbonylamino-4,4-dimethyl-3,5,10-trioxa-8-azatricyclo<6.4.0.02,6>undecan-9-one

diethyl (3RS,4SR,5SR,6RS)-3-t-butyldimethylsilyloxymethyl-4,5-dihydroxy-6-methoxyhexahydropyridazine-1,2-dicarboxylate