3,4-二苯胺基-3-环丁烯-1,2-二酮

3-(苄基氨基)-4-乙氧基-3-环丁烯-1,2-二酮

3,4-dimethylcyclobut-3-ene-1,2-dione

4-[(2-ethoxy-3,4-dioxocyclobuten-1-yl)amino]-3-hydroxybenzonitrile

3-(3H-benzimidazol-5-ylamino)-4-ethoxycyclobut-3-ene-1,2-dione