8,8,22,22-Tetramethyl-11,12,25,26-tetrahydro-10H,24H-dinaphtho[2,1-d:2',1'-n][1,3,11,13,7,17,2,12]tetraoxadiazadistannacycloicosine-10,24-dione AIDS-016477 AIDS016477 NSC670947