Spiro[3H-indole-3,4′-piperidine]-1′,5-dicarboxylic acid, 1,2-dihydro-2-oxo-, 1′-(1,1-dimethylethyl) ester
1′-(1,1-Dimethylethyl) 1,2-dihydro-2-oxospiro[3H-indole-3,4′-piperidine]-1′,5-dicarboxylate
1′-(tert-Butoxycarbonyl)-2-oxospiro[indoline-3,4′-piperidine]-5-carboxylic acid
1′-(tert-Butoxycarbonyl)-2-oxospiro[indoline-3,4′-piperidine]-5-carboxylicacid
1′-[(2-Methylpropan-2-yl)oxycarbonyl]-2-oxospiro[1H-indole-3,4′-piperidine]-5-carboxylic acid