diethyl (1SR,2RS,5RS,6SR)-2-t-butyldimethylsilyloxymethyl-5-methoxy-8,8-dimethyl-7,9-dioxa-3,4-diazabicyclo<4.3.0>nonane-3,4-dicarboxylate

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

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