20,20'(21H,21'H)-Spirobi[5H,19H-dibenzo[b,m][1,15,5,8,11]dioxatriazacyclooctadecine], 3,3',15,15'-tetrakis(1,1-dimethylethyl)-6,6',7,7',8,8',9,9',10,10',11,11',12,12',13,13'-hexadecahydro- AIDS-150920 AIDS150920 NSC689450