2-Butenoic acid, 3-methyl-, 1,3,3a,4,5,6a,7,7a,10,11,11a,11b-dodecahydro-1,2,11-trihydroxy-3,8-dimethyl-5,10-dioxo-2H-1,11c-(epoxymethano)phenanthro[10,1-bc]pyran-7-yl ester 6-.alpha.-Senecioyloxychaparrinone AIDS-031203 AIDS031203 NSC290494