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

(3S,7aR)-methyl 7-((3R,4R)-5-(benzyloxy)-4-hydroxy-3-methylpentyl)-3-tert-butyl-6-methyl-5-oxo-1,3,5,7a-tetrahydropyrrolo[1,2-c]oxazole-7a-carboxylate

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

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

(3S,7aR)-methyl 7-((3R,4R,1Z)-5-(benzyloxy)-4-hydroxy-3-methylpent-1-enyl)-3-tert-butyl-6-methyl-5-oxo-1,3,5,7a-tetrahydropyrrolo[1,2-c]oxazole-7a-carboxylate