1,3,3-Trimethylbenzoindolinopyranospiran 1,3,3-Trimethylindolinobenzopyrylspiran 1,3,3-Trimethylindolinobenzospiropyran 1485-92-3 157542-71-7 NSC 206174 Spiro(2H-1-benzopyran-2,2'-(2H)indole), 1',3'-dihydro-1',3',3'-trimethyl- Spiro(2H-1-benzopyran-2,2'-indoline), 1',3',3'-trimethyl-