1-Piperazinecarboxylic acid, 4-[(9S,14S,15R,16S,17R,18R,19R,20S,21S)-16-(acetyloxy)-9,10-dihydro-5,6,18,20-tetrahydroxy-14-methoxy-7,9,15,17,19,21,25-heptamethyl-10,26-dioxo-9,4-(epoxy[1,11,13]pentadecatrienoimino)furo[2',3':7,8]naphtho[1,2-d]thiazol-2-yl]-, phenylmethyl ester AIDS-113875 AIDS113875