2'-oxo-1',2'-dihydrospiro[cyclohex-4-ene-1,3'-indole]-2-carboxylic acid InChI=1/C14H13NO3/c16-12(17)10-6-3-4-8-14(10)9-5-1-2-7-11(9)15-13(14)18/h1-5,7,10H,6,8H2,(H,15,18)(H,16,17 spiro[cyclohex-4-ene-1,3'-[3H]indole]-2-carboxylic acid, 1',2'-dihydro-2'-oxo-