1,8-di-tert-butyl 2-methyl (2S,3aS,8aR)-3a-(3-methylbut-2-en-1-yl)-2,3,3a,8a-tetrahydropyrrolo[2,3-b]indole-1,2,8-tricarboxylate

2,3-di-tert-butyl 1a-methyl (1aS,2aR,7bS)-1H-cyclopropa[3,4]azeto[2,3-b]indole-1a,2,3(2aH)-tricarboxylate

1,8-di-tert-butyl 2-methyl (2S,3aR,8aS)-3a-methyl-2,3,3a,8a-tetrahydropyrrolo[2,3-b]indole-1,2,8-tricarboxylate