(9H-fluoren-9-yl)methyl (2R,2'S,4R,9a'S)-2'-methyl-3',5-dioxo-4-(((2,2,2-trichloroethoxy)carbonyl)amino)-2',3',4,5-tetrahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indole]-1'(9a'H)-carboxylate

(9H-fluoren-9-yl)methyl (2R,2'S,4R,9a'S)-4-(2-aminobenzamido)-2'-methyl-3',5-dioxo-2',3',4,5-tetrahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indole]-1'(9a'H)-carboxylate

benzyl (2R,2'S,4R,9a'S)-2'-methyl-3',5-dioxo-4-(((2,2,2-trichloroethoxy)carbonyl)amino)-2',3',4,5-tetrahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indole]-1'(9a'H)-carboxylate

methyl (2S,9R,9aS,αR)-9-hydroxy-α-[[(2,2,2-trichloroethoxy)carbonyl]amino]-2-methyl-3-oxo-1-[(phenylmethoxy)carbonyl]-2,3,9,9a-tetrahydro-1H-imidazo(1,2-a)indole-9-propanoate

2,2,2-trichloroethyl ((2R,2'S,4R,9a'R)-2'-methyl-3',5-dioxo-1',2',3',4,5,9a'-hexahydro-3H-spiro[furan-2,9'-imidazo[1,2-a]indol]-4-yl)carbamate