(3S,6S,7aR,E)-methyl 7-((3R,4R)-5-(benzyloxy)-4-(tert-butyldimethylsilyloxy)-3-methylpentylidene)-3-tert-butyl-6-methyl-5-oxohexahydropyrrolo[1,2-c]oxazole-7a-carboxylate

(3S,6S,6aS,7S,9aS)-7-[(2R,3R)-4-(benzyloxy)-3-{[tert-butyl(dimethyl)silyl]oxy}-2-methylbutyl]-3-tert-butyl-6a-hydroxy-6-methyldihydrofuro[3',4':2,3]pyrrolo[1,2-c][1,3]oxazole-5,9(6H)-dione

(3S,6R,6aS,7S,9aS)-7-[(2R,3R)-4-(benzyloxy)-3-{[tert-butyl(dimethyl)silyl]oxy}-2-methylbutyl]-3-tert-butyl-6a-hydroxy-6-methyldihydrofuro[3',4':2,3]pyrrolo[1,2-c][1,3]oxazole-5,9(6H)-dione

(3S,7aS)-methyl 3-tert-butyl-6-methyl-5-oxo-7-(trifluoromethylsulfonyloxy)-1,3,5,7a-tetrahydropyrrolo[1,2-c]oxazole-7a-carboxylate