NEW MATERIAL:A compound shown by the formula I [X is group shown by the formula II(R1 is H, 1W4C alkyl, or benzyl; R2 is H or 2W18C acyl); Y is group shown by the formula III (R3 is H, 1W4C alkyl, or benzyl); n is 1 or 3; Z is group shown by the formula IV (when n=1), etc.] and its salt.

EXAMPLE: 1,6,1,1-Tri-{N-[2-hydroxy-3-( 7,7,8,9,9-pentamethyl-2, 4-dioxo-1,3,8-triazaspiro[4,5]decane-3-yl )propyl]-N-( 2,2,6,6-tetramethyl-4-piperidyl )amino} undecane.

USE: A stabilizer for synthetic high polymers.

PROCESS: For example, a compound shown by the formula V is reacted with a compound shown by the formula (H2N)n-Z1(Z1 is group shown by the formula VI, etc.), and, if necessary, acylated, to give a compound shown by the formula I (with the proviso that X=Y).