3-ethoxy-4-phenylcyclobut-3-ene-1,2-dione

3,4-bis(butylamino)cyclobut-3-ene-1,2-dione

3,4-bis(tert-butylamino)cyclobut-3-ene-1,2-dione

2-氨基-1-乙氧基-3,4-二氧代-1-环丁烯

3-ethoxy-4-morpholin-4-ylcyclobut-3-ene-1,2-dione