An intermediate of the formula (I) wherein the radicals R1 are independently of one another methyl, ethyl or n-propyl, is suitable for preparing a compound of the formula (A) wherein X is a group of the formula (A-I) or (A-II), Y is C11-C17alkyl, and Z is a direct bond, —(CH2)8— or —CH2—S—CH2—. The compounds of the formula (A) are useful for stabilizing an organic material against thermal, oxidative or light induced degradation.