57 4-Hydroxy-2-cyclopentenones represented by the formula (I)
wherein X represents a hydrogen or halogen atom, A represents a hydrogen atom and B represents a hydroxyl group or A and B together represent a bond, R1 represents a substituted or unsubstituted alkyl, alkenyl or alkynyl group having up to 10 carbon atoms, R2 represents a substituted or unsubstituted alkyl, alkenyl or alkynyl group having up to 10 carbon atoms, and R3 represents a hydrogen atom or a protective group for a hydroxyl group; provided that R2 is not a 2-octenyl, 8-acetoxy-2--octenyl or 2,5-octadienyl group; are useful for the treatment of malignant tumors.
                            57 式(I)代表的 
4-羟基-2-环戊烯酮,其中 X 代表氢原子或卤素原子,A 代表氢原子,B 代表羟基或 A 和 B 共同代表键,R1 代表具有最多 10 个碳原子的取代或未取代的烷基、烯基或炔基,R2 代表具有最多 10 个碳原子的取代或未取代的烷基、烯基或炔基,R3 代表氢原子或羟基的保护基团;条件是 R2 不是 
2-辛烯基、8-乙酰氧基-
2-辛烯基或 2,5-
辛二烯基;可用于治疗恶性肿瘤。