NEW MATERIAL:The compound of formula I [R1 and R2 are H or lower alkyl, provided that both R1 and R2 are not lower alkyl at the same time; R3 is H or group of formula II; (a) when both R1 and R2 are H and R3 is group of formula II, then R4 is (CH2)nR5 or group of formula IIIWIV, etc.; R5 is lower alkoxy, phenylthio, etc.; R6 and R7 are H or lower alkyl, or R6 is phenyl, etc.; R8 is H, lower alkylcarbonyl, etc.; R9 is lower alkoxy, NH2, etc.; (b) when both R1 and R2 are lower alkyl and R3 is group of formula II, then R4 is lower alkyl, phenyl, lower alkoxy, etc.; and (c) when R3 is H, then R4 is the groups of R4 in the case (b) except for lower alkyl] and its non-toxic salt.

EXAMPLE: 1,2-bis[4-[ 2-(N-Methoxycarbonyl)aminoacetoxymethyl ]- 3,5-dioxopipe razin-1-yl]ethane.

USE: An antitumor agent suitable for drug preparation.

PREPARATION: The compound of formula I can be prepared by condensing the compound of formula V with the compound of formula R4COOH in the presence of a condensation agent.