Compounds obtained by the addition of unsaturated esters to the >NH group of compounds of formula II ##STR1## are useful as light stabilizers for polymeric materials, particularly for thermoplastic polymers and automotive finishes. Preferred compounds are those in which R, R.sub.1 and R.sub.2 are all hydrogen and R.sub.3 and R.sub.4 together with the carbon atom to which they are attached form a cyclododecylidene ring.