2,2,7,7,12,12,17-Heptamethyl-21,22,23,24-tetraoxapentacyclo[16.2.1.1~3,6~.1~8,11~.1~13,16~]tetracosa-1(20),3,5,8,10,13,15,18-octaene AIDS-132014 AIDS132014 NSC625151