3a,13a-[1]Propeno-3H-cyclopentacyclododecene-1,3,14,16-tetracarboxylic acid, 4,5,6,7,8,9,10,11,12,13-decahydro-2,15-dimethoxy-, tetrakis(1,1-dimethylethyl) ester AIDS-135287 AIDS135287 NSC634713