methyl (3'R,7a'R)-3'-(tert-butyl)-3-cyclohexyl-5',7'-dioxo-1'H,3'H,5'H-spiro[oxirane-2,6'-pyrrolo[1,2-c]oxazole]-7a'(7'H)-carboxylate

(3R,6R,6aR,9aS,9bS)-3-(tert-butyl)-10-methoxy-8-phenyl-6a,9a-dihydro-1H,3H,5H-6,9b-(azenometheno)oxazolo[3,4-a]pyrrolo[3,4-c]pyridine-5,7,9(6H,8H)-trione

(3R,6R,6aR,9aS,9bS)-3-(tert-butyl)-10-methoxy-6,6a,7,8,9,9a-hexahydro-1H,3H,5H-6,9b-(azenometheno)cyclopenta[c]oxazolo[3,4-a]pyridin-5-one

(3R)-3-tert-butyl-8-methoxy-6,8a-dihydro-1H-oxazolo[3,4-a]pyrazin-5(3H)-one