(1S,3S,4R,4'R,5'R)-tert-butyl 4',5'-diphenyl-3-(phenylsulfonyl)-7-azaspiro[bicyclo[2.2.1]hept[5]ene-2,2'-[1,3]dioxolane]-7-carboxylate

tert-butyl (3aR,4R,5R,6R,7R,7aS)-5-hydroxy-2,2-dimethyl-6-(phenylsulfonyl)hexahydro-4,7-epiminobenzo[d][1,3]dioxole-8-carboxylate

(1R,2S,3R,4S,6S)-tert-butyl 2,3-dihydroxy-5-oxo-6-(phenylsulfonyl)-7-azabicyclo[2.2.1]heptane-7-carboxylate

(1S,3R,4R)-tert-butyl 2-oxo-3-(phenylsulfonyl)-7-azabicyclo[2.2.1]heptane-7-carboxylate

(1R,2S,3R,4S,6R)-tert-butyl 2,3-dihydroxy-5-oxo-6-(phenylsulfonyl)-7-azabicyclo[2.2.1]heptane-7-carboxylate

(1R,2S,3R,4S,5R,6S)-tert-butyl 2,3,5-trihydroxy-6-(phenylsulfonyl)-7-azabicyclo[2.2.1]heptane-7-carboxylate

(1S,3S,4R,4'R,5S,5'R,6R)-tert-butyl 5,6-dihydroxy-4',5'-diphenyl-3-(phenylsulfonyl)-7-azaspiro[bicyclo[2.2.1]heptane-2,2'-[1,3]dioxolane]-7-carboxylate

tert-butyl (1S,3R,4R,4'R,5S,5'R,6R)-5,6-dihydroxy-4',5'-diphenyl-3-(phenylsulfonyl)-7-azaspiro[bicyclo[2.2.1]heptane-2,2'-[1,3]dioxolane]-7-carboxylate

tert-butyl ((3aR,4R,5R,6R,7R,7aS)-5,6,7-trihydroxy-2,2-dimethylhexahydrobenzo[d][1,3]dioxol-4-yl)carbamate

(3aR,4S,7S,7aS)-tert-butyl 2,2-dimethyl-5-oxohexahydro-4,7-epiminobenzo[d][1,3]dioxole-8-carboxylate