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

(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 (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