NEW MATERIAL:The compound of formula I (R1 is H or 1W5C alkyl; R2 and R3 are 1W18C alkyl) or formula II.

EXAMPLE: 3-Methoxycarbonylmethyl-4-methoxycarbonyl-N-(2,2,6,6-tetramethyl-4- piperidyl)-2-pyrrolidone.

USE: A photo-stabilizer for organic material such as synthetic polymer, and its intermediate.

PREPARATION: A mixture of the compounds of formula I and formula II can be easily produced, e.g., by reacting 1-R1-2,2,6,6-tetramethyl-4-aminopiperidine compound with 3-butene-1,2,3-tricarboxylic acid trialkyl ester in a solvent (e.g., methanol) under refluxing. The mixture can be separated into each compound, e.g., by column separation, however, it may be used in the form of mixture according to the purpose.