1,3,6,9-tetraphenyl-1,3,6,9-tetrazaspiro[4.4]nonane-2,4-dione

1,3-diphenylimidazolidine-2-thione

1,3-diphenylimidazolidin-2-one

2-(1-piperidine)isopropylamine

1,2,5,8-tetraphenyl-1,2,5,8-tetrazecane-6,7-dione